At the end of the study, participants taking the herbal product lost a mean of 5. Data from a year prospective observational study provide some insight into the long-term association between caffeine intake and body weight [ 49 ]. On average, participants gained some weight during the study, but men who increased their caffeine intake during the 12 years of follow-up gained a mean of 0.

For women, the corresponding mean difference in weight gain was 0. However, further research is needed to confirm this finding. For comparison, an 8-ounce cup of brewed coffee contains about 85— mg caffeine. Caffeine can cause sleep disturbances and feelings of nervousness, jitteriness, and shakiness.

Combining caffeine with other stimulants, such as bitter orange and ephedrine, can potentiate these adverse effects. Calcium is an essential mineral that is stored in the bones and teeth, where it supports their structure and function. Calcium is required for vascular contraction and vasodilation, muscle function, nerve transmission, intracellular signaling, and hormonal secretion [ 56 ].

Several studies have correlated higher calcium intakes with lower body weight or less weight gain over time [ ]. Two explanations have been proposed. First, high calcium intakes might reduce calcium concentrations in fat cells by decreasing the production of parathyroid hormone and the active form of vitamin D.

Decreased intracellular calcium concentrations, in turn, might increase fat breakdown and discourage fat accumulation in these cells [ 59 ].

Second, calcium from food or supplements might bind to small amounts of dietary fat in the digestive tract and prevent absorption of this fat [ 59 , 62 , 63 ]. Dairy products, in particular, might contain additional components that have even greater effects on body weight than their calcium content alone would suggest [ 60 , ].

For example, protein and other components of dairy products might modulate appetite-regulating hormones [ 61 ]. However, the results from clinical trials examining the effects of calcium on body weight have been largely negative.

Compared to placebo, calcium supplementation for 2 years had no clinically significant effects on weight. The authors of four reviews of published studies on the effects of calcium from supplements or dairy products on weight management reached similar conclusions [ ].

These reviews include a evidence report from the Agency for Healthcare Research and Quality whose authors concluded that, overall, clinical trial results do not support an effect of calcium supplementation on weight [ 70 ].

In addition, a meta-analysis of 41 randomized controlled trials found no benefit of calcium supplementation or increased dairy food consumption for body weight or body fat [ 73 ].

A meta-analysis of 33 randomized trials and longitudinal studies lasting 12 weeks to 6 years found that calcium from foods or supplements had no overall effect on body weight [ 74 ]. However, in subgroup analyses, calcium did reduce body weight in some groups, including children, adolescents, adult men, premenopausal women, women older than 60, and people with normal BMI [ 74 ].

Overall, the results from clinical trials do not support a clear link between higher calcium intakes and lower body weight, prevention of weight gain, or weight loss.

High intakes of calcium can cause constipation and might interfere with the absorption of iron and zinc, although this effect is not well established. High intakes of calcium from supplements, but not foods, have been associated with an increased risk of kidney stones [ 56 , ].

Capsaicinoids give chili peppers their characteristic pungent flavor. Capsaicin is the most abundant and well-studied capsaicinoid [ 78 ].

Capsaicin and other capsaicinoids have been proposed to have anti-obesity effects via their ability to increase energy expenditure and lipid oxidation, attenuate postprandial insulin response, increase satiety, and reduce appetite and energy intake [ ].

Other research suggests that capsaicin increases satiety by inducing gastrointestinal distress e. Most research on capsaicin and other capsaicinoids focuses on their effects on energy intake and appetite, rather than body weight.

A meta-analysis of eight randomized, placebo-controlled clinical trials evaluated the effects of capsaicinoids on ad libitum energy intake in a total of participants who had a normal body weight or were moderately overweight [ 78 ].

Doses of capsaicinoids ranged from 0. Overall, consuming capsaicinoids significantly reduced energy intake by a mean of 74 kcal per meal; body weight was not assessed, so the impact of this calorie reduction on weight loss cannot be quantified. The authors noted that the results suggest that at least 2 mg capsaicinoids are needed to reduce calorie intake but that the studies were very heterogeneous.

However, the calorie reductions did not significantly affect body weight at either 6 weeks or 12 weeks. It might also increase serum insulin and reduce high-density lipoprotein HDL cholesterol levels. Otherwise, capsaicin and other capsaicinoids appear to be safe. Research is underway to reduce the pungency and chili taste associated with capsaicin while retaining its potential biological effects [ 81 ].

Carnitine is the generic term for several compounds, including L-carnitine itself, several acylcarnitines e. It is composed of the amino acids lysine and methionine [ 84 ]. Carnitine is naturally present in animal products such as meat, fish, poultry, and milk and dairy products; small amounts are present in some plant foods.

Humans synthesize carnitine from its constituent amino acids, so dietary carnitine intake is not necessary. Almost all cells of the body contain carnitine, which transports fatty acids into the mitochondria and acts as a cofactor for fatty acid beta-oxidation [ 85 ].

Because of these effects, carnitine has been proposed as a weight-loss agent. A systematic review and meta-analysis combined the results from nine carnitine supplementation clinical trials in adults including the two described above that assessed weight loss [ 85 ].

The trials included a total of participants. In eight trials, the daily carnitine doses ranged from 1. Overall, study participants who received carnitine supplements lost an average of 1. Additional research on carnitine for weight loss is warranted. Rarer side effects include muscle weakness in patients with uremia and seizures in those with seizure disorders.

Some research indicates that intestinal bacteria metabolize carnitine to form trimethylamine N-oxide TMAO , a substance that might increase the risk of cardiovascular disease [ 91 ].

This effect appears to be more pronounced in people who consume meat than in vegans or vegetarians. The implications of this effect are not well understood and require more research. Chitosan is a manufactured polysaccharide that is commercially prepared from the exoskeletons of crustaceans.

It is purported to promote weight loss by binding to some dietary fat in the digestive tract, preventing its absorption [ 16 , 41 ]. Chitosan might also decrease cholesterol absorption [ 16 ]. Chitosan capsules taken before meals total of 2. However, the amount of fat that the chitosan trapped would result in a loss of only 1 lb body fat over about 7 months.

Chitosan had no significant effect on fecal fat excretion in the women compared to the control group. At the end of the study, those in the treatment group lost a mean of 1 kg body weight compared to a mean weight gain of 1.

In this study, chitosan treatment reduced body weight mean weight loss about 2. The authors of a Cochrane Review that included 13 trials examining the effect of chitosan on body weight found that chitosan, when taken for 4 weeks to 6 months, reduced body weight by a mean of 1.

They concluded that chitosan appears to be more effective than placebo for short-term weight loss, but most studies have been of poor quality. The authors also noted that results from high-quality trials indicate that chitosan has minimal effects on body weight, and these effects are probably clinically insignificant.

The adverse effects of chitosan are minor and primarily involve the gastrointestinal tract. They include flatulence, bloating, mild nausea, constipation, indigestion, and heartburn [ 93 , 95 , 96 ]. Because chitosan is derived from shellfish, people who are allergic to shellfish could theoretically be allergic to chitosan [ 97 ].

The trivalent form of chromium chromium III is an essential trace mineral that potentiates the action of insulin. Dietary supplements commonly contain chromium in the form of chromium picolinate, which consists of chromium and picolinic acid, although they might also contain other forms, including chromium nicotinate and chromium yeast [ 99 ].

Poor chromium status might contribute to impaired glucose tolerance and type 2 diabetes [ 98 ]. Researchers have hypothesized that chromium supplements increase lean muscle mass and promote fat loss, but study results have been equivocal [ 41 , ].

Some research indicates that these supplements might also reduce food intake, hunger levels, and fat cravings [ ], although data on these effects are sparse.

Several studies have evaluated the effects of chromium supplements, usually in the form of chromium picolinate, on weight loss. Six of the trials included resistance or weight training, and three did not. Chromium picolinate supplementation reduced body weight by 1.

Also in , a systematic review and meta-analysis of 11 randomized controlled trials including most of the trials evaluated in the Cochrane Review examined the effects of chromium supplementation in a total of individuals with overweight or obesity [ 99 ].

The authors concluded that daily doses of to 1, mcg chromium for 8 to 26 weeks reduce body weight by 0. Like the authors of the Cochrane Review, these authors noted that the effect is small and of "uncertain" clinical relevance. Similar findings were reported from an earlier meta-analysis of 12 trials [ ].

Trivalent chromium appears to be well tolerated. Adverse effects from clinical trials include watery stools, headache, weakness, nausea, vomiting, constipation, vertigo, and urticaria hives [ 99 , ].

Chromium does not have an established UL because few serious adverse effects have been linked to high intakes [ 98 ]. Hexavalent chromium chromium VI is toxic and not found in food or dietary supplements.

Forskolin is a compound isolated from the roots of Coleus forskohlii , a plant that grows in subtropical areas, such as India and Thailand. Forskolin is purported to promote weight loss by enhancing lipolysis and reducing appetite [ , ], possibly by stimulating cyclic adenosine monophosphate cAMP production.

This increased cAMP production, in turn, is thought to activate lipase and promote the release of fatty acids from adipose tissue [ 16 ]. Although animal studies indicate that forskolin reduces food intake [ , ], research in humans is very limited and inconclusive.

Compared to placebo, Coleus forskohlii extract had no effect on body weight, appetite, caloric intake, or macronutrient intake. In a study in mice, Coleus forskohlii extract caused dose-dependent hepatotoxicity, but pure forskolin did not have this effect, suggesting that other component s of Coleus forskohlii extract might be responsible for the hepatotoxicity [ ].

Forskolin has not been evaluated in longer term trials. Additional research is needed to better understand the safety and side effects of both short- and long-term use. Conjugated linoleic acid CLA is a mixture of linoleic acid isomers containing conjugated double bonds that is present mainly in dairy products and beef.

The various isomeric forms of CLA include c9,tCLA and t10,cCLA, and it is available in dietary supplements as a triacylglycerol or as a free fatty acid [ ]. Researchers have suggested that CLA enhances weight loss by increasing lipolysis and fatty acid oxidation in skeletal muscle, reducing lipogenesis, and promoting apoptosis in adipose tissue [ 17 , ].

Although CLA appears to reduce body fat mass in animals [ 17 ], results from human studies suggest that its effects are small and of questionable clinical relevance [ ]. One double-blind, placebo-controlled trial evaluated the effects of CLA supplementation as a mixture of c9,tCLA and t10,cCLA in male and female volunteers who were overweight BMI 25—30 consuming an ad libitum diet [ ].

Participants received CLA as a free fatty acid 3. At the end of the study, body fat mass dropped by significant amounts with both forms of CLA compared with placebo; reductions, on average, were 6.

Supplementation with CLA as a free fatty acid but not as a triacylglycerol also increased lean body mass compared with placebo. In another double-blind crossover trial, daily supplementation with CLA oil 6. These findings are similar to those from a randomized, double-blind, placebo- controlled trial in 63 adults with overweight or obesity BMI 24—35 that found statistically significant, but small, reductions in mean weight 0.

In contrast, those in the placebo group did not lose a significant amount of body weight 0. However, 3. The authors of a systematic review and meta-analysis of seven randomized controlled trials concluded that taking 2. However, the authors noted that the "magnitude of these effects is small, and the clinical relevance is uncertain.

CLA appears to be well tolerated. Most reported adverse effects are minor, consisting mainly of gastrointestinal disturbances, such as abdominal discomfort and pain, constipation, diarrhea, loose stools, nausea, vomiting, and dyspepsia [ 3 , , , , , ]. CLA might also increase some markers of oxidative stress and decrease breastmilk fat levels, but additional research is needed to confirm these effects [ ].

CLA has been linked to hepatitis in three case reports [ ]. However, whether CLA caused this toxicity cannot be definitively established because the products were not analyzed to rule out the presence of a contaminant. CLA might adversely affect lipid profiles, although results from studies are inconsistent.

Some research indicates that CLA has no major effect on lipid profiles, but other research shows that certain CLA isomers might decrease HDL cholesterol and increase lipoprotein a levels [ , , , ]. The CLA isomer t10,cCLA has also been reported to increase insulin resistance and glycemia in men with obesity and metabolic syndrome [ , ].

Fucoxanthin is a carotenoid in brown seaweed and other algae. Results from laboratory and animal studies suggest that fucoxanthin might promote weight loss by increasing resting energy expenditure and fatty acid oxidation as well as by suppressing adipocyte differentiation and lipid accumulation [ , ].

Only one clinical trial has been conducted on the possible weight-loss effects of fucoxanthin. This week trial used Xanthigen, a dietary supplement containing brown seaweed extract and pomegranate-seed oil [ ]. Compared to the placebo group, those receiving Xanthigen lost significantly more body weight by the end of the trial mean loss of 6.

The safety of fucoxanthin has not been thoroughly evaluated in humans. Although participants using Xanthigen in the clinical trial described above reported no adverse effects [ ], further investigation of the safety and potential side effects of fucoxanthin at various levels of intake is required.

Garcinia cambogia is a fruit-bearing tree that grows throughout Asia, Africa, and the Polynesian islands [ ]. The pulp and rind of its fruit contain high amounts of hydroxycitric acid HCA , a compound that has been proposed to inhibit lipogenesis, increase hepatic glycogen synthesis, suppress food intake, and reduce weight gain [ 6 , 15 , , , ].

Studies in rats have found that Garcinia cambogia suppresses food intake and inhibits weight gain [ 3 ]. In humans, however, the evidence on whether Garcinia cambogia or HCA is effective for weight loss is conflicting, and any effects it has appear to be small [ 6 , 17 , ].

In one randomized, placebo-controlled trial, 89 women who were mildly overweight mean BMI Women receiving Garcinia cambogia lost significantly more weight 3. However, Garcinia cambogia did not alter appetite, and the study produced no evidence that the supplement affected feelings of satiety.

Participants in both groups lost weight, but the between-group weight-loss differences were not statistically significant. HCA also had no effect on body fat loss. A review and meta-analysis of 12 randomized controlled trials with a total of participants examined the effects of Garcinia cambogia on weight loss [ ].

Therefore, the effect of Garcinia cambogia on body weight remains uncertain. The reported adverse effects of Garcinia cambogia and HCA are generally mild and include headache, nausea, upper respiratory tract symptoms, and gastrointestinal symptoms [ , , ].

However, dietary supplements containing Garcinia cambogia have been implicated in three cases of mania, which might have been caused by the serotonergic activity of HCA [ ]. Symptoms included grandiosity an unrealistic sense of superiority , irritability, pressured speech, and decreased need for sleep.

Reports have also described 10 cases of liver toxicity, resulting in one death and two liver transplants, in people taking products containing Garcinia cambogia [ 43 , ].

In most of these cases, the products contained other botanical ingredients and minerals as well, so the toxicity cannot be definitively attributed to Garcinia cambogia. Because all clinical trials of Garcinia cambogia and HCA have been short, its long-term safety is unknown.

Glucomannan is a soluble dietary fiber derived from konjac root Amorphophallus konjac that can absorb up to 50 times its weight in water [ 16 ]. Like guar gum, glucomannan has been proposed to increase feelings of satiety and fullness and prolong gastric emptying by absorbing water in the gastrointestinal tract [ 16 , , ].

It might also reduce fat and protein absorption in the gut [ 16 ]. Glucomannan appears to have beneficial effects on blood lipids and glucose levels [ ], but its effects on weight loss are inconsistent. At the end of the study, glucomannan produced significantly greater weight loss mean loss of 2.

In another study conducted in the United States, supplementation with glucomannan 3. Eight weeks of glucomannan supplementation 1. The authors of a systematic review of six randomized controlled trials with a total of participants concluded that 1.

Similarly, a meta-analysis of eight trials that included participants found that glucomannan did not significantly affect weight loss compared to placebo [ ]. The authors of an older meta-analysis of 14 studies designed primarily to investigate glucomannan's effect on lipid and blood glucose levels concluded that 1.

Little is known about the long-term safety of glucomannan. Glucomannan appears to be well tolerated for short-term use, with minor adverse effects, including belching, bloating, loose stools, flatulence, diarrhea, constipation, and abdominal discomfort [ , , , ]. The use of tablet forms of glucomannan was reported to be associated with seven cases of esophageal obstruction in — in Australia [ 99 ].

Users should therefore be cautious when taking glucomannan tablets. Powdered and capsule forms have not been associated with this effect [ ].

The seeds or beans of the coffee plant Coffea arabica, Coffea canephora, Coffea robusta are green until they are roasted. Compared to roasted beans, green coffee beans have higher levels of chlorogenic acid.

Green coffee extract, probably because of its chlorogenic acid content, inhibits fat accumulation in mice and humans by regulating adipogenesis. Green coffee extract also modulates glucose metabolism [ ], perhaps by reducing glucose absorption in the gut [ ].

Green coffee beans contain caffeine see section on caffeine above [ ], although decaffeinated forms are available [ 16 ]. In mice, green coffee bean extract in combination with a high-fat diet significantly reduced body weight gain and fat mass [ , ].

Only a few clinical trials have examined the effects of green coffee bean extract on weight loss in humans, and all were of poor methodological quality. The researchers concluded that green coffee bean extract has a moderate but significant effect on body weight mean weight loss of 2.

The authors of another small clinical trial claimed to show a benefit of green coffee bean extract for weight loss [ ], but the study was strongly criticized by the FTC for having several critical flaws in its design [ , ]. Two of the three study authors subsequently retracted the journal publication.

Green coffee bean extract appears to be well tolerated, but its safety has not been rigorously studied. Reported adverse effects include headaches and urinary tract infections [ ]. The caffeine naturally present in green coffee beans acts as a stimulant and can cause adverse effects, depending on the dose and whether it is combined with other stimulants see section on caffeine above.

Green tea Camellia sinensis is a popular beverage consumed worldwide that has several purported health benefits [ ]. Green tea is present in some dietary supplements, frequently in the form of green tea extract.

The active components of green tea that are associated with weight loss are caffeine see section on caffeine above and catechins, primarily epigallocatechin gallate EGCG , which is a flavonoid [ 41 , ].

A typical brewed cup of green tea has about — mg catechins [ ] and 45 mg caffeine. It has been suggested that green tea and its components might reduce body weight by increasing energy expenditure and fat oxidation, reducing lipogenesis, and decreasing fat absorption [ 41 , ].

Green tea might also decrease carbohydrate digestion and absorption [ ]. Available green tea extracts cover the range from minimally processed tea leaves to highly processed, manufactured concentrates of single constituents, such as EGCG.

The authors of a meta-analysis of six randomized controlled trials with a total of 98 participants found that caffeine alone or in combination with catechins significantly increases energy expenditure in a dose-dependent fashion compared with placebo [ ].

This effect might be important for maintaining weight loss by helping counteract the decrease in metabolic rate that can occur during weight loss. Catechins combined with caffeine also significantly increase fat oxidation, but caffeine alone does not. Other human research indicates that EGCG alone does not increase resting metabolic rate, fat oxidation, or the thermic effect of feeding the increase in metabolic rate associated with the digestion and absorption of food [ , ].

Taken together, these findings suggest that green tea catechins and caffeine might act synergistically [ 41 , , ].

Several human studies have examined the effects of green tea catechins on weight loss and weight maintenance. A Cochrane Review analyzed the results from 14 randomized controlled trials of green tea preparations in a total of 1, participants with overweight or obesity [ ]. The trials lasted from 12 to 13 weeks, and doses of green tea catechins ranged from to 1, mg; in 10 of the 14 trials, the green tea preparations contained caffeine.

Green tea supplementation reduced body weight by a mean of 0. However, when the authors analyzed the six studies that were conducted outside of Japan where study methodologies were less heterogeneous than in the Japanese studies , they found no statistically significant difference in weight loss for green tea compared to placebo.

The authors reported that green tea catechins combined with caffeine over a median of 12 weeks modestly yet significantly reduced body weight by a mean of 1. Only two studies in this meta-analysis examined the effects of green tea catechins alone.

Their results suggest that green tea catechins alone do not affect body weight or other anthropometric measurements.

A meta-analysis of 11 randomized controlled trials found that people who took EGCG combined with caffeine for 12—13 weeks lost a mean of 1. In , EFSA examined health claims related to green tea and concluded that "a cause and effect relationship has not been established between the consumption of catechins including EGCG from green tea … and contribution to the maintenance or achievement of a normal body weight" [ ].

Taken together, the findings of these studies suggest that if green tea is an effective weight-loss aid, any effect it has is small and not likely to be clinically relevant [ , ]. No adverse effects have been reported from the consumption of green tea as a beverage [ ].

For green tea extract, most reported adverse effects are mild to moderate, and they include nausea, constipation, abdominal discomfort, and increased blood pressure [ ]. Toxicology studies in rats and mice show that green tea extract does not cause cancer but does cause nonneoplastic lesions in many areas of the body, including the nose, liver, and bone marrow [ ].

Other evidence in mice shows that high doses of catechins cause liver toxicity. There is also increasing evidence in humans that green tea extract might cause liver damage, though the underlying mechanism is not well understood [ ]. An analysis of 1, postmenopausal women participating in the Minnesota Green Tea Trial found that women who consumed green tea extract containing 1, mg total catechins including mg EGCG and Consumption of some green tea extracts—primarily ethanolic extracts of green tea—has also been linked to liver damage in at least 50 case reports since [ 43 , ].

In , the U. Pharmacopeia USP systematically reviewed the safety of green tea products [ ]. The USP noted that problems are more likely when green tea extract is taken on an empty stomach and, therefore, advises taking green tea extracts with food to minimize the possible risk of liver damage.

Other researchers and medical experts advise using dietary supplements containing green tea extract only with caution [ ]. Guar gum is a soluble dietary fiber derived from seeds of the Indian cluster bean Cyamopsis tetragonolobus [ 16 , ].

Guar gum is present in certain dietary supplements and is an ingredient in some food products, especially gluten-free baked goods, because it helps bind and thicken these products. Like glucomannan, guar gum is purported to promote weight loss by acting as a bulking agent in the gut; delaying gastric emptying; increasing feelings of satiety; and, theoretically, decreasing appetite and food intake [ 16 , ].

However, guar gum does not appear to enhance weight loss. In a meta-analysis of 20 randomized, double-blind, placebo-controlled trials that statistically pooled data from 11 trials, Pittler and colleagues evaluated the effects of guar gum for body weight reduction in a total of adults [ ].

Trial participants included people with hypercholesterolemia, hyperlipidemia, or type 1 or type 2 diabetes; menopausal women; and healthy volunteers.

Compared with placebo, guar gum had no significant effect on weight loss. The authors concluded that guar gum is not effective for body weight reduction. Reported adverse effects for guar gum are primarily gastrointestinal and include abdominal pain, flatulence, diarrhea, increased number of bowel movements, nausea, and cramps [ , , ].

Case reports indicate that guar gum can cause severe esophageal and small-bowel obstruction if taken without sufficient fluid [ , ].

However, these reports were about a guar gum product that is no longer available [ ]. In their meta-analysis, Pittler and colleagues concluded that given the adverse effects associated with the use of guar gum, the risks of taking it outweigh its benefits [ ].

Hoodia gordonii is a succulent plant that grows in the Kalahari Desert of southern Africa. The San people have traditionally used hoodia as an appetite suppressant during long hunts. This anecdotal evidence, combined with results of a few animal studies indicating that hoodia reduces food intake [ ], led to the widespread marketing of hoodia as a weight-loss supplement in the United States in the early s.

Scientists have not determined the exact mechanism whereby hoodia might suppress appetite. A glycoside commonly called P57, which may have central nervous system activity [ ], is widely believed to be the main active ingredient, although not all researchers agree [ 16 , ].

Despite its popularity as a weight-loss supplement, very little scientific research on hoodia has been conducted in humans [ ].

Compared to placebo, hoodia extract had no significant effect on energy intake or body weight. Hoodia has been reported to cause significant increases in heart rate and blood pressure [ ]. It also raises bilirubin and alkaline phosphatase levels which may indicate impaired liver function , although the clinical significance of these findings is unclear because hoodia has not been reported to affect levels of other liver enzymes.

Other side effects include headache, dizziness, nausea, and vomiting. In the past, some hoodia products were found to contain little or no hoodia [ ]. The human microbiota, which outnumber human cells by up to fold, have myriad roles in human health [ , ].

Although microbes are found throughout the human body, the vast majority inhabit the colon. The gut microbiota play an important role in nutrient and energy extraction from food. Research in mice suggests that the gut microbiota affect not only use of energy from the diet but also energy expenditure and storage within the host [ ].

Whether these effects translate to humans is unknown. However, manipulating the gut microbiota has been proposed as a method to prevent or treat obesity in humans, and probiotics might provide a way to accomplish this.

Probiotics are in foods, such as some yogurts, as well as dietary supplements. The many different genera of probiotics include Lactobacillus, Streptococcus, and Bifidobacterium, which all have widely varying effects in the body [ , ].

Much of the research on probiotics and its influence on the gut microbiota and obesity has been in mice, and the results have been promising.

For example, probiotic supplementation reduced body weight gain and fat accumulation in obese mice fed a high-fat diet [ ]. In humans, however, results of clinical trials that assessed the impact of probiotics on obesity-related endpoints have been inconsistent.

In another randomized clinical trial, daily supplementation with 3. However, among the 77 female participants, the Lactobacillus supplementation did significantly reduce body weight after 12 weeks loss of 1.

Another recent systematic review and meta-analysis of 15 randomized controlled trials in individuals with overweight or obesity found that supplementation with various doses and strains of probiotics for 3 to 12 weeks resulted in larger reductions in body weight by 0.

However, these effects were small and of questionable clinical significance. The most recent systematic review and meta-analysis, which included 19 randomized trials in 1, participants, found that supplementation with probiotics or synbiotics products containing both probiotic organisms and prebiotic sugars, which microorganisms in the gastrointestinal tract use as metabolic fuel reduced waist circumference slightly by 0.

The findings from another meta-analysis of 14 trials in adults, 5 trials in children, and 12 trials in 1, infants suggested that probiotics promote an average loss of 0. Taken together, these results indicate that the effects of probiotics on body weight and obesity might depend on several factors, including the probiotic strain, dose, and duration as well as certain characteristics of the user, including age, sex, and baseline body weight.

Additional research is needed to understand the potential effects of probiotics on body fat, body weight, and obesity in humans. Many probiotic strains derive from species with a long history of safe use in foods or from microorganisms that colonize healthy gastrointestinal tracts.

For these reasons, the common probiotic species—such as Lactobacillus species acidophilus, casei, fermentum, gasseri, johnsonii, paracasei, plantarum, rhamnosus, and salivarius and Bifidobacterium species adolescentis, animalis, bifidum, breve, and longum —are unlikely to cause harm [ ].

Side effects of probiotics are usually minor and consist of self-limited gastrointestinal symptoms, such as gas. In a few cases, mainly involving individuals who were severely ill or immunocompromised, the use of probiotics has been linked to bacteremia, fungemia fungi in the blood , or infections that result in severe illness [ , ].

For individuals with compromised immune function or other serious underlying diseases, the World Gastroenterology Organisation advises restricting probiotic use to the strains and indications that have proven efficacy [ ]. Pyruvate is a three-carbon compound that is generated in the body through glycolysis [ ].

Pyruvate is also available as a dietary supplement, frequently in the form of calcium pyruvate. Researchers have suggested that pyruvate enhances exercise performance and reduces body weight and body fat, possibly by increasing lipolysis and energy expenditure [ 6 , , ].

Only a few studies have examined the effects of pyruvate supplementation in humans. Although some of these studies suggest that pyruvate decreases body weight and body fat, others do not. At the end of the trial, the pyruvate group had significant decreases in body weight mean loss of 1.

In the placebo group, these measurements did not change significantly compared to baseline. However, a double-blind, placebo-controlled trial in 23 women who were overweight mean BMI Healthcare professionals continue to recommend a caloric deficit and physical activity as superior methods to lose weight sustainably and safely 2 3 4.

However, there are valid reasons why someone might want to use a so-called fat-burning supplement. While thermogenic ingredients have yielded marginal effects in clinical trials for fat loss 5 , some folks may find that these supplements help them lose weight a little faster. Athletes, physique competitors and bodybuilders with strict weigh-in requirements immediately come to mind.

However, fat burners should not be used by everyone, particularly pregnant women, women who are breastfeeding, underaged consumers, persons with certain medical issues e.

We've included expert insights on several of the featured products from Pete Nastasi and Roger Lockridge. Nastasi is a certified weight loss practitioner and sports nutrition expert, and Lockridge is a longtime fitness enthusiast and writer.

This content is meant to be informative, but should not be taken as medical advice. It is not intended for use as diagnosis, prevention or treatment of health problems.

Always speak with your doctor before starting any new supplement or exercise regimen. If you have a history of eating disorders, disordered eating or any underlying health conditions it is important to discuss your weight loss goals with a doctor first.

Note: Roger Lockridge recently tried PhenQ for 30 days and wrote about his experience and results in our PhenQ review. I didn't want to try it for energy purposes, but rather for appetite control.

It definitely delivered on that front. I would feel satisfied sooner, which led to a reduction in the calories I was taking in.

That combined with my training led to a weight loss of over 8 pounds in 30 days. I also dropped a pants size, which made me even happier. People who are starting on their weight loss journey may benefit from the simplicity of taking it. I think any person focusing on health and wellness may find this to be a worthy addition to their program or plan.

While the PhenQ fat burner isn't a magic bullet, it has ingredients that have been researched for safety and could give you a boost as part of a weight loss program. The company has also added InnoSlim, B vitamins and iodine to the formula. PhenQ apparently has thousands of positive reviews from users who have had success, although the company notes on its website that results vary from person to person.

The Transparent Labs Recomp is a rebrand of what was formerly called the Transparent Labs Fat Burner. The product is the same, and before the rebrand, it had 4. It currently has 10 reviews and earns 4. However, several customers complain that the pills are difficult to swallow due to their size.

Check out our Transparent Labs Review for more information on this popular supplement brand. Related Post: The Best Appetite Suppressants and Diet Pills To Control Hunger and Boost Metabolism. Legion Athletics Phoenix is considered a natural fat burner with a 4.

Every bottle is tested individually at an ISO lab to confirm the quality and safety of ingredients. Related Post : Does Coffee Suppress Appetite? Instant Knockout has many of the same ingredients found in similar weight loss products, including green tea extract and cayenne pepper.

Athletes and bodybuilders might love the effects of Instant Knockout, but casual gym-goers could find the caffeine content to be too intense. It has a 3. This eliminates the need to worry about negative side effects such as anxiety, jitters and trouble sleeping, which are commonly experienced when using high-stim fat burner supplements.

Regarding the ingredients, Clean Burn is a combination of Carnipure, green tea leaf extract, GS4 Plus and Capsimax, along with the mineral chromium in the form of chromium picolinate.

In my opinion, this is a well-formulated product because all of these ingredients have shown potential weight loss benefits, especially when taken in the correct dosages.

For example, Carnipure L-carnitine L-tartrate in doses of 2, milligrams per day has been shown to provide a modest reduction in body weight, fat mass and BMI, especially in overweight individuals That said, if you plan on using Clean Burn as recommended, this will provide 3, milligrams per day, which may cause side effects such as nausea, vomiting, abdominal cramps, diarrhea and a fishy body odor Another key ingredient is the green tea extract—dosed at milligrams per serving—close to 1, milligrams per day.

At these dosage levels, studies have shown significant weight loss results, along with a decrease in total cholesterol levels without any side effects The final ingredient I want to mention is the chromium picolinate.

While the research suggests that chromium may play a role in carbohydrate, lipid and protein metabolism, more studies need to be done to determine how this actually takes place.

I want to talk about this mineral because the dosage level of micrograms per serving far exceeds the adequate intake level of 35 micrograms per day for men and 45 micrograms per day for women.

While some studies have used dosage levels of up to 1, micrograms of chromium per day, some adverse effects at these higher concentrations have been reported.

Chromium also has the potential to interact with certain medications taken for diabetes, such as insulin and metformin This is why we highly recommend that you consult with a primary healthcare provider before taking Kaged Clean Burn to ensure your safety.

Kaged Clean Burn uses five ingredients that the company says work together to help you burn fat, boost metabolism and manage your weight without using stimulants. Our reason for classifying it as the best thermogenic fat burner is that there is some science to support the list of ingredients in the product, including chromium for blood glucose control 29 , green tea extract for fat metabolism 13 , capsaicinoids for potential thermogenic properties 26 and L-carnitine which may support body weight reduction Currently, it is rated 4.

It is third-party tested and certified drug-free by the BSCG. Related Post: The Best Teas for Losing Weight and Boosting Your Metabolism. PhenQ PM's lack of caffeine and stimulants makes it an obvious choice for a nighttime fat burner. PhenQ claims that the formula's amino acid content can also promote better sleep and support nighttime fat burning.

Each four-capsule serving contains a total amino acid dosage of 2, milligrams—1, milligrams apiece of L-lysine and L-arginine, plus milligrams of L-theanine and milligrams of 5-HTP.

Judging PhenQ PM by customer reviews is difficult since the page for this specific product on the PhenQ website currently has just one testimonial. You can read our full assessment of this product in our PhenQ PM review.

Both chromium picolinate and acetyl-L-carnitine also provide a potential fat loss benefit, with chromium playing a key role in fat metabolism 62 and L-carnitine supplementation demonstrating modest reduction effects in body weight, body mass index BMI and total fat mass in numerous studies.

Transparent Labs Lean uses ingredients and dosing specifically targeted at improving endurance and converting fats to energy during workouts. Like other Transparent Labs products, it's third-party tested.

It currently has a 4. The reason why we chose it as the pre-workout fat burner is because of its BCAA, beta-alanine and betaine contents—all of which have been shown to positively affect stamina during weight training and endurance exercise 64 Related Post: The Best Pre-Workout Supplements on the Market, According to a Nutrition Coach.

Based on this ingredients list, this product is designed to help individuals convert stored body fat into usable energy.

That being said, aside from the caffeine which is dosed at milligrams per two-capsule serving size, I would like to see more acetyl L-carnitine and green tea extract in this product.

The current scientific literature supports a 2-gram per day serving of L-carnitine and greater than milligrams per day of green tea extract to support your weight loss goals.

Jacked Factory Burn XT is a simple formula that has only five active ingredients: acetyl-L-carnitine HCL, green tea leaf extract, caffeine anhydrous, Capsimax cayenne pepper extract and BioPerine black pepper extract. Lab-based studies can measure representations of your metabolism using bloodwork and special devices.

Related Post: Best Fat Burning Foods. Thermogenic fat burners may include any number of ingredients, with each affecting the body in different ways. We've already touched on many of the ingredients typically found in the best weight loss supplements that focus on fat-burning, including green tea, Capsimax powder, B vitamins and caffeine.

Other common ingredients in thermogenic supplements include:. Related Post: Apple Cider Vinegar for Weight Loss. First, the ingredients provided by supplements are typically based on dosages that have been researched for safety and efficacy.

Second, individuals may develop a tolerance to several ingredients found in thermogenic supplements—meaning that they become less effective. Certain studies indicate that this may ring true regarding the arousal effects of caffeine and yohimbine, and the thermogenic effects of active ingredients in green tea extract For those new to thermogenic supplements, a more conservative approach is to start with a small dose ex: a quarter or half of a recommended serving and gradually increase the dosage to test your tolerance, but never exceed the recommended dosage.

If you experience unwanted side effects, stop using the product altogether. It's important to stay well hydrated while using a thermogenic fat burner supplement.

Along with a balanced diet, regular physical activity and good sleep, drinking plenty of water can effectively aid in weight loss. Related Post: Does Drinking Water Help You Lose Weight? Finished dietary supplements, like those used for fat-burning and weight loss, are regulated by the FDA under the Dietary Supplement Health and Education Act DSHEA of However, the vastness of the supplement industry may result in some products entering the market before full evaluation, so consumers should exercise caution and seek professional advice when considering supplements.

Even if a substance has not been banned by the FDA, it may still cause unwanted side effects. These are some of the main precautions for thermogenic ingredients:. Many supplements used for fat burning contain herbs or other ingredients found in plants.

For example, the natural herb ephedra is banned by the FDA because it was linked to serious side effects such as heart attack, seizure, stroke and sudden death DMAA is also not generally recognized as being safe Thermogenic supplements that contain stimulants e.

Collagen is the most easily digested protein and can help heal your body in addition to helping your metabolism. A meta-analysis published in the Journal of the American College of Nutrition examined the effect of whey protein, with and without resistance exercise, on body weight and body composition.

Researchers found that adults supplementing with whey experienced significant decreases in body fat and body weight. The results were even more significant among adults who combined whey protein supplementation with resistance exercise.

Quality greens powders contain fat-burning compounds like green tea, green coffee and rhodiola that can boost your energy. They also contain green foods like chlorella, wheatgrass juice and kale that may help improve digestion and bloating.

Try taking one scoop mixed with water before or after exercise. Fish oil is a rich source of omega-3 fatty acids, specifically EPA and DHA.

These healthy fats can help reduce inflammation and may work to improve body composition and counteract obesity-related metabolic changes. Vitamin D is a vitamin and pro-hormone that can help balance hormones, which aids in fat loss.

Take 1, milligrams of fish oil daily and 2, I. of vitamin D3. Probiotics are involved in energy homeostasis, regulation of appetite, dietary intake and storage of lipids. Taking a daily probiotic can support digestion and may also help manage blood sugar, particularly when combined with prebiotics and a high-fiber diet.

Yohimbe or yohimbine is an herbal supplement. Yohimbine may have certain fat-burning abilities and work even better while someone is fasting.

Although not every study has shown that yohimbe can have slimming effects, certain other studies have found positive results. One study found that yohimbine significantly increased mean weight loss in overweight female patients following a low-energy diet.

Taurine is a type of amino acid that is found in the tissues throughout the body. It can also be produced in small amounts. L-taurine is often added to energy drinks for those looking to take advantage of the potential taurine benefits.

It is believed to be associated with a number of health benefits, such as increased fat-burning during exercise and improved heart health. Want to know how to lose weight fast? One option is trying the ketogenic diet. A ketogenic diet is an extremely low-carb diet in which you drastically reduce or completely eliminate the amount of glucose you eat.

Once glucose has been eliminated from the body and there are no carbs available for your body to use for energy, the body will turn to stored fat instead, putting you into the metabolic state called nutritional ketosis. By drastically reducing our intake of carbs, our bodies release less insulin.

Less insulin in our bloodstreams means glycogen is used by our bodies as energy and not stored — and when that supply is over, it turns to fat next.

A low-carb diet is a diet that limits carbohydrate foods — such as foods with added sugar, grains, starchy vegetables and fruit — and emphasizes foods high in protein and fat. There are various types of low carb diets in existence, one of which is a high-protein diet.

Low-carb diets tend to be either very high in fat or high in protein. If you choose to follow a high-protein diet, which is what the Atkins Diet and the South Beach Diet could both be considered, your diet will be roughly distributed as 30 to 35 percent calories from protein, 20 percent or less from carbohydrates, and about 45 to 50 percent from fat.

Similarly, carb cycling is a type of diet plan that involves eating more carbohydrates on certain days of the week, but doing the opposite on the other days: cutting carbs very low in order to achieve easier weight loss.

While there are different levels of vegetarian and vegan diets , most vegetarians steer clear of eating meats, including seafood and poultry. What do vegans eat? Well, they take it a step further and avoid all products that come from animals, including dairy and eggs. Simply swap out meat, fish, etc.

for clean proteins like legumes, lentils, quinoa, etc. several times per week or more. There are plenty of ways to get protein without consuming too many animal-derived foods, such as from nuts, seeds, beans, ancient grains or plant-based protein powders.

A plant-based diet is naturally low in fat and high in fiber. People who follow a traditional Mediterranean diet know how to lose weight naturally without going to extremes.

Made popular by the fortunate folks living in one of the most beautiful regions on Earth, people on the Mediterranean diet enjoy fresh fruits and vegetables, embrace fats like olive oil, and eat high-quality poultry and seafood, all in close-to-natural states.

With the allowance of an occasional glass of red wine or steak, this diet allows you to enjoy food and the occasional indulgence. The Paleo diet continues to be a good option. The Paleo concept of going grain-free can be greatly beneficial, as you strip away nutritionally bankrupt, starchy calories that spike insulin levels and instead usually replacing with more vegetables.

Along with jettisoning grain, sugar a major inflammatory and disease creator is forbidden. Instead, the diet relies on popular anti-inflammatory foods like wild-caught salmon, blueberries, leafy greens and nuts.

Also, let those close to you know of your intentions. One, getting emotional support for your goal is always helpful.

Plus, it can help eliminate bad feelings that arise once you start making different choices. Share a post-workout selfie or join an online community where members cheer each other on. Keeping an exercise or food diary can help you see weaknesses in your routine, push yourself out of a fitness plateau or notice what situations drive you to eat more or exercise less.

Pencil workouts into your daily planner the same way you do dinner with friends or that important business meeting. Opt for shorter bouts of exercise throughout the day instead, which science suggests has a similar benefits to doing longer workouts.

Try a quick cardio circuit in the morning, a brisk stroll during your lunch hour and an after-dinner strength session. First, crank up the music. All you have to do is add your favorite fast-paced jams to a playlist and get moving. Second, consider exercising with a group.

Classes also provide an opportunity to try something new in a safe, supportive environment. Embracing a healthy lifestyle means cutting out some things you might have taken for granted, like after-work happy hours with coworkers or weekend brunches with friends.

Instead, suggest fun alternatives, like taking a new exercise class together, going on a hike or checking out a spin class.

And while a pound of fat is still the same as a pound of muscle, because muscle is lean and smooth, you can be shedding inches while remaining the same weight.

To get a more accurate depiction of how your body is changing, use body measurement tape instead to track your size and progress. Changing every part of your lifestyle at once is overwhelming and sets you up for failure.

Decide on making just one healthy change a week to allow yourself time to adapt. A chronic lack of sleep is linked to weight gain, diabetes and more. Protein can support fat burning and weight loss in many ways.

For example, people who consume high-protein foods may feel fuller for longer. Eating protein may also increase metabolism, allowing the body to more efficiently burn fat. Some high-protein foods contain fewer calories than high-carbohydrate foods. For example, a large bowl, or grams g , of cooked, plain spaghetti contains calories and 7.

In contrast, two large hard-boiled eggs contain calories and To boost weight loss, many sources recommend a daily intake of 1—2 g of protein per kilogram of body weight.

To maximize weight loss, a person should try to choose lower-calorie proteins, such as lean chicken, fish, and plant-based proteins. They should avoid consuming excessive amounts of red meat, fried foods, or foods with added oil, fat, or butter. Polyphenols are a group of chemicals present in many foods, particularly fruits and vegetables.

Some research suggests that polyphenol-rich foods may aid weight loss. A study found that a diet rich in polyphenols may interact with bacteria in the intestines to support weight loss, especially when combined with a diet low in probiotics. Other studies of specific polyphenol-rich foods, such as curcumin, have also found an association with weight loss.

For instance, a study found that taking curcumin supplements increased weight loss more than placebo in people who were overweight and had metabolic syndrome.

The study followed 47 people from Finland who drank coffee but had stopped drinking coffee for a month. The researchers found an association between coffee consumption and metabolites. When trying to burn fat, it is best to choose low-calorie coffee options by avoiding high-calorie sweeteners, milks, and creams.

Probiotics are live bacteria and yeast that are beneficial to human health. Many foods contain probiotics, including yogurts and fermented foods such as kimchi, sauerkraut, and tempeh. Probiotics are also available as dietary supplements. The digestive system is home to trillions of bacteria.

Research suggests that consuming probiotics can help improve the natural balance between helpful and harmful bacteria in the gut, as well as support digestion. Some health practitioners also claim that these gut-dwelling bacteria may play a role in metabolism and weight loss.

However, a systematic review found no data to support the notion that consuming probiotics has a significant effect on weight loss. The researchers concluded that more studies are necessary.

Green tea is also rich polyphenols. Some studies have found a small increase in weight loss among people who regularly consume green tea. However, a systematic review of previous research found that this weight loss was not statistically significant.

The review also found that green tea played no role in maintaining weight loss. Sugar cravings are a major barrier to weight loss for many people. Curbing sugar cravings with fruit may help a person consume fewer calories.

Some research suggests that preloading may be helpful to people wishing to lose weight. Preloading involves consuming a dense, low-calorie food or drink before a main meal so that the person feels fuller and eats less.

A study found that adults with obesity who preloaded with grapefruit, grapefruit juice, or water before meals decreased their total calorie intake.

Several pills and supplements promise to help people lose weight. Why it works: Green coffee extract contains chlorogenic acid, a compound that helps your body release stored fat. In addition, green coffee extract reduces the release of insulin, helping to keep your blood sugar in check.

It also helps prevent your body from storing carbs as body fat, so you primarily use carbs to fuel workouts when you consume them shortly before training. How to use it: Take —mg of green coffee extract 2—3 times a day between meals.

Inside look: The active component is epigallocatechin gallate EGCG , a phytochemical that is found in green and black tea leaves. This natural occuring phytochemical has a wide range of health boosting possibilities such as reducing the chances of heart disease, cancer, and high cholesterol.

Why it works: As a weight-loss aid, green tea extract helps reduce body fat by boosting metabolic rate—the number of calories you naturally burn every day. It also helps release stored fat by helping your body maintain levels of the neurotransmitter norepinephrine, so more fat is burned as fuel rather than being shuttled back into storage.

Unlike with caffeine, many people find that they can take green tea extract later in the day without it affecting their sleep habits. Inside look: Derived from red raspberries, raspberry ketones are chemicals that the body makes when fats are broken down for fuel.

Why it works: Supplementing raspberry ketones helps spare muscle tissue, encouraging your body to rely on stored fat for energy. How to use it: To increase fat loss while following a reduced-calorie diet plan, take —mg of raspberry ketones about 30 minutes before meals.

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