Each serving is one capsule that you take once in the morning and once at lunch. One serving packs about mg of caffeine anhydrous, which is nearly the entire recommended mg per day. We also had to give this product a 3. Read our full PhenQ Review. This fat burner is formulated with eight active ingredients to potentially help you burn fat through thermogenesis, which is the process of generating heat in the body that can potentially increase your metabolism.

This pick contains ingredients designed to reduce cravings and increase energy without causing caffeine jitters. We gave this formula a 4 out of 5 for its potentially fat-burning ingredients, including mcg micrograms of chromium and mg of cayenne pepper extract, as well as ingredients like konjac root extract to help reduce food cravings.

Konjac root extract contains glucomannan, which is a dietary fiber. Fiber not only helps keep you regular in the bathroom but it may help keep you feeling fuller for longer, potentially making it easier to follow a calorie-restricted diet or avoid cravings.

Konjac glucomannan may also help lower your blood sugar and improve your cholesterol, potentially helping promote weight loss. Hourglass Fit requires you to take one capsule and can work best if you take it four times daily with a glass of water.

This product may be an excellent fat burner for women who are looking to minimize food cravings and decrease body fat. Chromium and vitamin B6 may be helpful ingredients to potentially aid in regulating your BMI and metabolism.

Our team gave Hourglass Fit a 3. You can definitely find cheaper alternatives out there. Unlike most other fat burners, this one comes in a powder that you can easily mix in your shaker bottle and sip on-the-go.

And you can choose from several different flavors. But considering this fat burner is a powder, not a pill, your body may be able to absorb the supplement more quickly, resulting in a faster-working fat burner.

Since many people struggle with portion control and cravings, the apple cider vinegar ACV in this formula is especially helpful. This ingredient can help control blood sugar levels, according to the Cleveland Clinic.

Generally, more controlled blood sugar may help promote appetite control but more research is needed to show whether ACV can help promote weight loss. This product is also packed with ingredients that have thermogenic properties like capsicum fruit extract, guayusa tea extract, and caffeine.

In some cases, artificial sweeteners can cause digestive unrest, which may only worsen with some of the other ingredients in this supplement.

We gave this fat burner a 4. While you may be able to find some cheaper products, this is still on the price-friendly side of the spectrum. Jacked Factory Lean-PM is free of stimulants, so you can reap the potential benefits of a fat burner without disrupting your sleep schedule.

Leading off the lineup is mg of green tea extract, which may increase fat loss. However, green tea does have trace amounts of caffeine, so for athletes who have a strict no-caffeine rule, this pick may not work.

The main sleep-focused ingredients in this formula are the 5g of melatonin a sleep-promoting hormone and mg of magnesium. It also helps promote proper muscle and nerve function, which is helpful both in and out of the gym.

We gave this formula a 4 out of 5, as we liked the option to buy this product with or without melatonin. You also get about 36 percent of your daily recommended value of magnesium and more than percent of your daily recommended value of vitamin B6. How does good sleep help with fat loss and lean muscle maintenance?

When you sleep, your body recovers and repairs the muscle damage it undergoes during training, leaving you with stronger muscle tissue. And while good quality sleep may be associated with more strength, short sleep duration may contribute to decreased muscle strength.

The formula on this stim-free fat burner is rather short but to the point. There are components to potentially aid in burning fat, while helping to promote good sleep. But some fat burners may help curb those cravings and suppress your appetite.

Pretty much all of the ingredients on this list are status quo, but Leanbean differentiates itself by overcoming hunger cravings.

This formula uses a dietary fiber called glucomannan, which can swell your stomach slightly to create a feeling of fullness. You get acai berry, green coffee, choline, vitamin B6, and vitamin B However, these are nutrients that are helpful for your overall health, so we gave this formula a 3.

This product is marketed specifically to women but any athlete, regardless of their gender, can try this supplement. Leanbean sits on the more expensive end of the spectrum, earning a 3 out of 5 for cost per serving. Read our full Leanbean Review. Legion's Phoenix is made completely of all-natural ingredients and herbs, which is unlike most other fat burner products.

You can also buy this in a caffeine-free version. Sometimes read: almost always quality will cost you. However, this fat burner boasts great ingredients with useful extras, and actually comes at a fairly reasonable price.

This is a pretty complete fat burner, earning a 4 out of 5 for formula. People taking certain medications like SSRIs, MAOIs, or tricyclic antidepressants should check with a doctor before taking this supplement.

So, if you have pre-existing health conditions or are taking other medications, you may want to chat with a doctor or steer clear of this product.

In addition to these less common ingredients, this fat burner also contains mg of caffeine and a dose of B vitamins, which are more common in fat burners. An added perk with this product is that if you want to go stim-free, you have the option to remove the caffeine at checkout.

Plus, this one is available on Amazon Prime, so you can get it in a matter of days. Read our full Legion Phoenix Fat Burner Review. For the most part, fat burners are safe but they may not be appropriate for every person. That said, fat is an energy source that your body stores to use.

Having your macros dialed in and training consistently should always come first, but certain ingredients in fat burners have been shown to coax your body into using or oxidizing stored fat. Specifically, green tea extract — well, the compound EGCG, found in green tea — and L-carnitine.

Your body burns calories necessary for fat loss simply by regulating normal functions, like breathing, temperature regulation, and organ function. Most fat burners include capsaicin or capsimax extracted from chili peppers and caffeine to increase your internal temperature.

In doing so, your body works with higher intensity to cool down and burn more calories. At that point, an extra 50 to calories a day may help.

And eating a calorie deficit can be tough, especially when you need to train at a high intensity, too. This is why many fat burners contain ingredients like 5-HTP, fiber, and psyllium husk to help you feel full.

Do fat burners work? Well, fat burners work mainly by triggering a thermogenic response in your body and bumping up your resting metabolic rate RMR , the rate at which your body burns calories while at rest. Some also contain stimulants like caffeine for increased energy during fat-burning exercise, as well as ingredients that may suppress your appetite.

Interested in learning more about how and if fat burners really work? This video explains more. While the FDA takes measures to ban dangerous substances from fat burners, they may still cause some unwelcome side effects.

Fat burners with stimulants like caffeine or beta-alanine can cause increased heart rate, nausea, dizziness, and irregular heartbeats.

People with pre-existing medical conditions or those who are taking other medications should consult a physician before trying a fat burner. While fat burners can speed up fat loss, remember that they are designed as a supplement to not a replacement for a healthy, low-calorie diet and regular exercise.

The cost of a fat burner goes up when you add extra ingredients to the fat-burning blend. While most fat burners will include a blend of common ingredients, like cayenne pepper extract, caffeine, and green tea extract, the more expensive products will include ingredients like DMAE, which can improve mood.

But be sure to read the packaging of the specific product you buy, as it may have different recommendations. You can also take your fat burner about 30 minutes before your workout. Since fat burners contain a lot of ingredients that can help supply energy like caffeine , it may be beneficial to take them pre-workout for an added jolt of energy.

However, be cautious when you take them as a pre-workout supplement. If you do decide to take it, follow the instructions on the label, unless otherwise directed by your physician.

The best way to use a fat burner is to start with half or a quarter of the recommended dosage and gradually increase your intake to test your sensitivity. If you start to feel unwanted side effects, drop the dosage or stop taking the product. As we discussed, fat burners use ingredients that may help with fat oxidation, thermogenesis, and appetite suppression.

While many fat burners include ingredients that do all three of these things, oftentimes a product will lean more heavily toward one of the three in particular.

Before you decide which fat burner you want to buy, you should consider which of these processes you want to prioritize. We recommend sticking to products that disclose the dosage of every ingredient in their fat burner.

Though you can take your fat burner when you wake up in the morning to jumpstart your metabolism, many people choose to take their fat burners before they workout. If you take a fat burner with caffeine too late in the day, it could potentially mess with your sleep. While a healthy diet, caloric deficit, and consistent exercise regimen are the best tools you can have for your weight-loss goals, fat burners can be helpful supplements.

If your nutrition, wellness, and workout routine are on point, fat burners may help you suppress your appetite, increase your metabolism, and burn a little extra fat. That said, most fat burners include common ingredients in reasonable doses.

There are tons of different fat burner options, each with its own ingredients intended to help with burning fat. They take different approaches to reach this goal, but our current favorite is Jacked Factory Burn-XT. Its transparent label, simple yet effective formula, and multifaceted approach make it the best available right now, in our opinion.

Following your macros, training hard, and even upping your daily step count should come first. You cannot — we repeat, cannot — take only a pill or powder and expect results.

If you eat well and train a few times a week, however, a fat burner may help expedite the process a little bit. But if you find yourself consistently craving calorie-dense, processed foods, you may want to reevaluate your daily diet and potentially add some nutritious calories to your meals.

It depends on both your health and the fat burners. Some fat burners generally stim-free ones only contain natural ingredients that are usually safe for daily consumption. On the other hand, others contain ingredients that can be harmful if taken in high doses or over a long period of time.

Keep in mind, many fat burners are meant to be taken in week cycles, not over the course of months or years. View All Articles. BarBend is an independent website.

The views expressed on this site may come from individual contributors and do not necessarily reflect the view of BarBend or any other organization.

BarBend is the Official Media Partner of USA Weightlifting. Skip to primary navigation Skip to main content Skip to primary sidebar Roundups. Exogenous ketones induce a similar but different metabolic state than that of naturally occurring ketones.

More research is needed to determine their effect on ketosis and weight loss. Whether or not weight loss gummies work is up for debate.

The same goes for other weight loss supplements. At best, supplements provide a minimal or modest boost to weight loss efforts, according to the National Institutes of Health NIH. At worst, they provide no benefit whatsoever. The only FDA-approved weight loss supplement is alli , which contains orlistat.

The manufacturer explains that for every 5 pounds of weight you lose, alli may help you lose at least 2—3 pounds more. Oprah went on record last year explaining that her name was used without her permission to promote Great Results Keto AVC Gummies.

This product has 3. Most recent reviews say the gummies do not work. In a interview with British Vogue , Adele explains that she lost pounds by exercising. She says she works out 2—3 times a day — weights in the morning, hiking or boxing in the afternoon, and additional cardio in the evening.

Losing 20 pounds in a month is not realistic for most people. Centers for Disease Control CDC experts recommend losing weight through diet and exercise at a rate of pounds a week. More research is needed to determine if weight loss gummies are truly effective. Speaking with a doctor before taking them is always a good idea.

They can also provide exercise and eating pattern recommendations to help you maintain a moderate weight. Our experts continually monitor the health and wellness space, and we update our articles when new information becomes available.

Drinking water can help reduce appetite and make you burn more calories. Several studies show that water can help you lose weight. Many studies show that green tea can help you lose weight.

It contains bioactive substances that can make you burn more calories, even at rest. Having a healthy snack on hand can help you add nutrients to your diet and feel less hungry when you sit down to a meal. Here are 29 healthy snacks…. Patients with diabetes who used GLP-1 drugs, including tirzepatide, semaglutide, dulaglutide, and exenatide had a decreased chance of being diagnosed….

Some studies suggest vaping may help manage your weight, but others show mixed…. The amount of time it takes to recover from weight loss surgery depends on the type of surgery and surgical technique you receive. New research suggests that running may not aid much with weight loss, but it can help you keep from gaining weight as you age.

Here's why. New research finds that bariatric surgery is an effective long-term treatment to help control high blood pressure. Most people associate stretch marks with weight gain, but you can also develop stretch marks from rapid weight loss. A Quiz for Teens Are You a Workaholic?

How Well Do You Sleep? Health Conditions Discover Plan Connect. Do Weight Loss Gummies Actually Work? Medically reviewed by Adrienne Seitz, MS, RD, LDN , Nutrition — By Ashley Marcin on November 6, How gummies work Safety Consumer reports say Keto gummies Versus other supplements FAQs Takeaway Weight loss gummies claim to burn fat, suppress appetite, and otherwise support the quest to shed pounds.

How do gummies help you lose weight? Ingredient Impact on weight loss green tea may have a modest effect green coffee bean extract may have a modest effect ketones not enough evidence garcinia cambogia little or no effect caffeine may have a modest effect.

Which gummies work best for weight loss? Are weight loss gummies safe? Possible side effects. ingredient potential side effects green tea constipation, nausea , increased blood pressure , and liver damage green coffee bean extract urinary tract infections , headaches ketones none identified garcinia cambogia nausea, headache, stomach upset, mania , liver damage caffeine fast heart rate , jitteriness, or vomiting ACV laxative effect.

What do consumer reports say about weight loss gummies? Do they make keto gummies for weight loss? How do gummies compare to other weight loss supplements?

Frequently asked questions. How we reviewed this article: Sources. Healthline has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical associations. We avoid using tertiary references. You can learn more about how we ensure our content is accurate and current by reading our editorial policy.

Nov 6, Written By Ashley Marcin. Medically Reviewed By Adrienne Seitz, MS, RD, LDN.

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 The authors of a systematic review and meta-analysis of six randomized controlled trials in a total of participants concluded that 5—30 g pyruvate for 3—6 weeks reduces body weight by a mean of 0.

However, the authors noted that the methodological quality of all trials is weak, preventing them from drawing firm conclusions.

The safety of pyruvate has not been rigorously studied. Pyruvate might also increase LDL levels and decrease HDL levels [ , ]. Additional research is needed to better understand the safety and possible side effects of this compound.

Raspberry ketone is the primary aroma compound found in red raspberries Rubus idaeus , and it is added to some foods as a flavoring agent [ 16 , ]. In vitro and animal studies suggest that raspberry ketone might help prevent weight gain by increasing fatty acid oxidation, suppressing lipid accumulation, and inhibiting pancreatic lipase activity [ 16 ].

Although it has been touted on the Internet and national television as an effective way to burn fat, little evidence exists to support this claim. In mice fed a high-fat diet, raspberry ketone supplementation reduced food intake and body weight compared to the same diet without raspberry ketone [ ].

Only one randomized controlled trial has examined the effects of a dietary supplement containing raspberry ketone on weight loss. This product contained 2, mg of a proprietary blend of raspberry ketone, caffeine, bitter orange, ginger, garlic, cayenne, L-theanine, and pepper extract along with B-vitamins and chromium.

During the 8-week study, participants followed a calorie-restricted diet approximately calories less per day than estimated needs and engaged in moderate exercise 60 minutes 3 days per week.

Compared to the placebo group, those receiving METABO lost significantly more body weight mean loss of 1. However, 25 of the 70 participants dropped out of the study, and results were reported for only the 45 participants who completed the study i.

Furthermore, the product contained many ingredients in addition to raspberry ketone, making it impossible to determine the effects of raspberry ketone alone. Typical diets provide only a few mg of raspberry ketone a day.

Doses contained in dietary supplements typically range from to 1, mg, and the safety of such doses has never been evaluated in humans [ ]. Participants in the METABO study described above had no serious adverse effects [ ].

However, additional research on raspberry ketone is needed to better understand its safety and side effects. Vitamin D, which is fat soluble, is present in a few foods, such as fatty fish, cheese, egg yolks, and vitamin D-fortified milk.

It is also available in many dietary supplements, and humans synthesize it naturally when their skin is exposed to sunlight. Vitamin D promotes calcium absorption in the gastrointestinal tract and is needed for proper bone growth and remodeling [ 56 ].

Observational studies indicate that greater body weights are associated with lower vitamin D status, and individuals with obesity frequently have marginal or deficient circulating levels of vitamin D [ ].

Nevertheless, the association between vitamin D and obesity raises the question of whether increasing vitamin D concentrations might reduce body weight [ , ]. Despite the association between low vitamin D levels and obesity, scientific evidence does not support a cause-and-effect relationship.

The authors commented that the cause of this finding might have been stored vitamin D in body fat and skeletal muscle that was released during weight loss. However, according to a meta-analysis of 12 vitamin D supplementation trials including 5 in which body composition measurements were primary outcomes , vitamin D supplements without calorie restriction did not affect body weight or fat mass compared to placebo [ ].

Overall, the available research suggests that consuming higher amounts of vitamin D or taking vitamin D supplements does not promote weight loss. For the best results, start with a small dose to check your tolerance and gradually increase the dosage until you reach the recommendation for daily use.

Never exceed the recommended daily dosage, and always check with your physician or a registered dietitian nutritionist first.

Thermogenic supplements typically come in pill or powder form. Pills are typically swallowed and taken with a glass of water. Powdered supplements in general are mixed into water or a sports drink and taken with a meal or snack.

Some may be suitable to consume on an empty stomach. Stick to your budget, and remember to optimize your diet, physical activity and sleep—a supplement is just the cherry on top of your weight management efforts. Among them are:. Learn more about our product review process and supplements rating methodology.

Taking fat burners and other types of diet pills can be safe as long as you do it responsibly. The first requirement is that you check with your healthcare provider before taking them, as you would with any type of supplement. Fat burners could pose a risk to your health depending on your medical history, your current health status and whether you're taking medications that might cause an interaction.

Also, people with a history of eating disorders should not take weight loss pills. The second step of responsible use is to follow the manufacturer's recommendations for how and how often to use the supplement.

Even for healthy individuals, fat burners and other types of over-the-counter weight loss pills could cause health issues if consumed in excess of the recommended dosage.

Fat burners typically work by stimulating a thermogenic response in your body, thereby increasing your resting metabolic rate RMR. Some contain stimulants like caffeine to provide an energy boost during your workout, which may help you burn more calories.

They may also decrease your appetite, though the study results do not always show promise. Related Post: Do Weight Loss Pills Work?

Maybe, but it depends largely on the fat burner's formula, the recommended dosage and your health status. Some fat burners contain only water-soluble ingredients that are generally safe to consume every day.

On the other hand, some formulas have ingredients linked to adverse health effects in high or repeated dosages, such as bitter orange and hoodia Also, keep in mind that interventional and toxicity studies on fat burners often have a study window of around 12 weeks.

There remains a need for high-quality research on the effects of long-term fat burner pill usage, as many studies show inconsistent results, are poorly done or are not well controlled The makers of the best weight loss pills are transparent about their ingredients and upfront about the potential risks while emphasizing the recommended dosages.

As always, check with your physician before starting any dietary supplement. Research has shown that certain ingredients in fat burner supplements can promote thermogenesis and boost metabolism, possibly leading to increased fat burning.

Supplements sold over the counter typically highlight testimonials from users that show dramatic results.

While this information can be useful in helping you decide whether to try fat-burning pills and other weight-loss supplements, remember two key points: scientific studies take place under specifically controlled conditions, and results can vary greatly from person to person.

Also, keep in mind that using fat-loss supplements without incorporating exercise and a healthy diet is unlikely to produce lasting results.

Many, many experts agree that even the best fat burner supplement can't do the job alone. So do any weight loss supplements really work, fat burners included? The more useful question might be, "Can fat burners play one part in my weight management plan? Nutrition and exercise are the headliners, but safe weight loss pills that can further help your body burn fat and maintain a more robust metabolism have the potential to play a supporting role.

Chris Mohr , RD and Ph. Chris Mohr is a registered dietitian who holds a Ph. in exercise physiology. He has worked with athletes ranging from NFL players to WWE wrestlers, along with celebrities and executives worldwide.

He has been a featured speaker at many conferences around the world. Eddie Jo is a professor of exercise physiology and the director of the Cal Poly Pomona Human Performance Research Lab.

His research serves to innovate and advance the application of exercise training methodologies, nutrient intake and technologies for the optimization of human health and performance, energy metabolism, body composition and endocrine function.

Tim Ziegenfuss , PhD, CSCS, FISSN. Tim Ziegenfuss is a standout in the world of sports nutrition and exercise science, bolstered by graduate degrees from Purdue University and Kent State University. Beyond academia, he serves as a Past President and Fellow of The International Society of Sports Nutrition, steering the field toward higher standards.

As CEO of The Center for Applied Health Sciences, his focus is overseeing innovative research with real-world impact and guiding product ideation and creation for major retailers all around the world. Jenevieve Roper , Ph. D, CSCS.

Jen Roper is an Associate Professor of Health and Human Sciences at Loyola Marymount University. She received her PhD in Physical Education, Sports and Exercise Science in from the University of New Mexico, with a specialization in Exercise Science and Biomechanics.

Askarpour, M. Efficacy of l-carnitine supplementation for management of blood lipids: A systematic review and dose-response meta-analysis of randomized controlled trials. Nutrition, Metabolism and Cardiovascular Diseases, 29 11 , — Hodgson, A. The effect of green tea extract on fat oxidation at rest and during exercise: Evidence of efficacy and proposed mechanisms.

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Show references AskMayoExpert. Weight management adult. Mayo Clinic; Obesity adult. Pilitsi E, et al. Pharmacotherapy of obesity: Available medications and drugs under investigation.

Perreault L. Obesity in adults: Drug therapy. Accessed Oct. Prescription medications to treat overweight and obesity. National Institute of Diabetes and Digestive and Kidney Diseases. Accessed Aug. Melmed S, et al. In: Williams Textbook of Endocrinology.

Elsevier; Patel K. Obesity treatment: A focus on pharmacotherapy of weight management. Papadakis MA, et al. McGraw Hill; Shah M expert opinion. Mayo Clinic. Apovian CM, et al. Pharmacological management of obesity: An Endocrine Society clinical practice guideline. Journal of Clinical Endocrinology and Metabolism.

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