12 scientifically-backed supplements to lose weight fast

Weight loss solutions come in many forms. 

Supplements, pills and drugs are some of the more popular options. Combining these methods with other methods may enable you to lose weight, or at least make it easier.

Losing weight with supplements

Weight loss supplements tend to work through one or more of these mechanisms:

  • Reducing appetite so you eat fewer calories
  • Limiting the absorption of nutrients, such as fat, thereby reducing calorie intake
  • Burning more calories by increasing fat metabolism

It’s crucial to onsult a doctor or healthcare provider before making any changes to your diet or supplements. Here are the 12 most widely used weight loss pills and supplements, evaluated by science [1]:

1. Bitter orange (Synephrine)

The compound synephrine can be found in bitter oranges. Synephrine is related to ephedrine, which used to be a prominent ingredient in various weight-loss pill formulations [2]. Nevertheless, the FDA has since banned ephedrine as a weight-loss ingredient because of severe side effects [ 3].

How it works: Synephrine has similar mechanisms to ephedrine but is less powerful. It could help reduce appetite and increase fat burning [4].

Effectiveness: Very few studies have been done on synephrine, but many studies have found that ephedrine can cause substantial short-term weight loss [5].

Side effects: Like ephedrine, synephrine may have adverse side effects related to the heart. It may also be an addictive substance.

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2. Caffeine

Caffeine is the world’s most commonly consumed psychoactive substance [6]. Many processed foods and beverages contain it, as well as coffee, green tea and dark chocolate. Because caffeine is considered to be a metabolism booster, companies usually add it to commercial weight loss supplements.

How it works: One study examined the effect of caffeine on managing body weight by raising energy expenditure, essentially meaning you burn more calories because of increased fat breakdown as well as via a process of body heat production called thermogenesis [7].

Effectiveness: Some studies indicate that caffeine can cause moderate weight loss in humans [89].

Side effects: In some people, high amounts of caffeine can lead to anxiety, diarrhea, insomnia, irritability, jitteriness, nausea and other symptoms. Caffeine is also a stimulant and can reduce the quality of your sleep. There is no requirement to take a supplement or a pill with caffeine. The best choices are quality coffee and green tea, which also have antioxidants and other health benefits [10].

12 scientifically-backed supplements to lose weight fast

3. Conjugated linoleic acid (CLA)

For years, CLA has been a popular fat loss supplement. The trans fat found in cheese and butter is considered one of the “healthier” trans fats.

How it works: CLA may suppress appetite, enhance metabolism and promote the breakdown of body fat [11].

Effectiveness: In a comprehensive review of 13 studies, it was found that CLA caused weight loss of about 1.1 pounds (0.52 kg) in comparison with a placebo. This number grew to 2.3 pounds (1.05 kg) in people over the age of 44 [12]. Compared with a placebo, CLA may help you lose about 1.5 pounds (0.7 kg). Finally, the authors question the clinical relevance of CLA’s small weight loss effect [13].

Side effects: CLA can cause digestive side effects and may contribute to fatty liver, insulin resistance and inflammation over the long term.

4. Forskolin

Weight loss is thought to be possible with forskolin, an extract from a mint plant.

How it works: It may raise concentrations of a compound inside cells called cAMP, which can promote fat burning [14].

Effectiveness: Forskolin reduced body fat and increased muscle mass without affecting body weight in a study of 30 overweight or obese men. In another study, 23 women with excess weight did not experience any effects [15].

Side effects: There is insufficient data on the efficacy of this supplement or the risk of side effects.

5. Garcinia cambogia extract

After being featured on “The Dr. Oz Show” in 2012, garcinia cambogia became popular worldwide. It’s a small, green fruit that looks like a pumpkin. Garcinia cambogia extract, marketed as a diet pill, contains the active ingredient hydroxycitric acid in the fruit’s skin.

How it works: Animal studies show that it can block a fat-producing enzyme in the body and raise serotonin levels, thereby helping to reduce cravings [16].

Effectiveness: In a meta-analysis, researchers explored four electronic research databases to look into the efficacy of herbal medicines, including garcinia cambogia. In a total of 54 randomised controlled trials in healthy adults with overweight or obesity, the authors found no reduction in weight or body fat percentage between the garcinia cambogia group and the placebo group [17]. A 2020 review that assessed eight trials on garcinia cambogia found that, on average, it caused weight loss of about 3 pounds (1.34 kg) [18].

Side effects: While it’s widely accepted that garcinia cambogia is safe to take in recommended amounts, reports within the last few years have drawn attention to some severe side effects. A 2018 study reported four cases of women who suffered from acute liver failure after taking weight loss supplements containing garcinia cambogia [19]. In addition, hepatotoxicity, or liver impairment and some episodes of mania have also been reported in connection with taking garcinia cambogia [2021].

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6. Green tea extract

Many weight loss supplements contain green tea extract. Its main antioxidant, EGCG, has been demonstrated to aid in fat burning in numerous studies.

How it works: In combination with reduced fat absorption, green tea extract can be an effective method to treat obesity by inhibiting enzymes like pancreatic lipase [22].

Effectiveness: Several studies have shown that green tea extract, combined with exercise, can increase fat burning and cause fat loss, especially around the belly [2324].

Side effects: In general, green tea extract is well tolerated. Those who are sensitive to caffeine may show symptoms from it since it contains some caffeine. Green tea extract may also provide all the health benefits associated with drinking green tea.

7. Glucomannan

Glucomannan is a type of fiber found in the roots of the elephant yam, which is also known as konjac.

How it works: Glucomannan absorbs water and becomes gel-like. It “rests ” in your gut and promotes a feeling of fullness, helping you eat fewer calories [25].

Effectiveness: According to one clinical trial, taking glucomannan for 60 days could lower body weight among overweight participants, but only if they took the supplement consistently [26].

Other benefits: Fibers like glucomannan can feed the beneficial bacteria in our intestines. It can also lower blood sugar, blood cholesterol and triglycerides and works well against constipation [2728].

Side effects: It can cause bloating, flatulence and soft stools and can interact with some oral medications if taken at the same time. It is advisable to take glucomannan about half an hour before meals, with a glass of water.

8. Green coffee bean extract

Green coffee beans are simply coffee beans that haven’t been roasted.

They contain two substances believed to help with weight loss: caffeine and chlorogenic acid.

How it works: Caffeine can increase fat burning, and chlorogenic acid can slow the absorption of carbohydrates in the gut.

Effectiveness: Several human studies have shown that green coffee bean extract could help people lose weight [29]. The supplement has a significant impact on minimising body mass index according to a meta-analysis of all currently available randomised control trials on green coffee bean extract and obesity.

Other benefits: Green coffee bean extract may aid in lower blood sugar levels and reduce blood pressure. It is also high in antioxidants [30].

Side effects: It can cause the same side effects as caffeine. The chlorogenic acid it contains may also result in diarrhea, and some people may be allergic to green coffee beans [31].

9. Hydroxycut

Among the most popular weight loss supplements in the world, Hydroxycut has been around for more than a decade. The brand makes several products, but the most common is simply called “Hydroxycut.”

How it works: It contains various ingredients that are said to help with weight loss, including caffeine and a few plant extracts like green coffee extract.

Effectiveness: A 2011 meta-analysis of five clinical trials found that supplementation with C. canephora robusta, or green coffee extract, one of the key ingredients in Hydroxycut, contributed to about a 5.5-pound (2.47-kg) weight loss in comparison with the placebo [32].

Side effects: If you are intolerant to caffeine, you may feel anxiety, jitteriness, tremors, nausea, diarrhea and irritability [33]. Cardiovascular risks and liver toxicity led to the removal of Hydroxycut products from shelves in 2004 and 2009, respectively [34]. Hydroxycut supplements have also been linked to acute liver injury [35].

10. Meratrim

The diet pill Meratrim is relatively new to the market. A combination of two plants extracts, Sphaeranthus indicus and Garcinia mangostana, which may alter fat cell metabolism.

How it works:. It claims to make it tougher for fat cells to reproduce, decrease the amount of fat they pick up from the bloodstream and help them burn stored fat.

Effectiveness: Very few studies about Meratrim exist. One study involved 60 people with obesity placed on a strict 2,000-calorie diet and increased physical activity, with either Meratrim or a placebo. After 8 weeks, the Meratrim group had lost 11 pounds (5.2 kg) and 4.7 inches (11.9 cm) off their waistlines [36].

Side effects: No side effects have been documented.

11. Orlistat (Alli)

Xenical and Alli are the names of pharmaceutical drugs that contain orlistat.

How it works: This weight loss pill works by interfering with the breakdown of fat in your gut, resulting in taking fewer calories from fat.

Effectiveness: A 2003 meta-analysis of studies found that people taking orlistat for 12 months in tandem with lifestyle changes saw a 2.9 percent greater weight reduction than the placebo group [37].

Other benefits: Orlistat has been shown to reduce blood pressure to some extent and may lower the risk of developing type 2 diabetes when used alongside lifestyle changes [38].

Side effects: This drug has many digestive side effects, including loose, oily stools, flatulence and frequent bowel movements that are hard to control. It may also contribute to a deficiency in fat-soluble vitamins (A, D, E and K). Following a low-fat diet while taking orlistat is often recommended to minimise side effects. Interestingly, a low-carb diet (without medication) has been considered as effective as orlistat and a low-fat diet combined. There was no significant difference in blood sugar or lipid levels between the two diets in terms of weight loss. However, orlistat combined with a low fat diet was more successful at lowering blood pressure [39].

12. Raspberry ketones

In raspberries, raspberry ketone contributes to their distinct smell. There is a weight loss supplement that contains synthetic raspberry ketones.

How it works: In isolated fat cells from mice, raspberry ketones stimulate the breakdown of fat and raise levels of a hormone called adiponectin, which is believed to be linked to weight loss [40].

Effectiveness: There are very few studies on raspberry ketones in humans, though one 2013 study looked at raspberry ketones along with some other ingredients and found a potential 2 percent increase in weight loss over 8 weeks when compared with a placebo. One mouse study using massive doses showed some reduction in weight gain.

However, high raspberry ketones were also correlated with higher blood sugar levels and higher levels of ALT, a liver enzyme, suggesting liver dysfunction. It’s unclear whether these effects would apply to humans. More research is necessary to determine any benefits and risks.

Side effects: They may cause your burps to smell like raspberries.

Weight loss prescription medications

There has also been some success with prescription weight loss pills. Contrave and Phentermine are the most commonly prescribed. Despite what you may think, prescription weight loss pills don’t work as well as they’re supposed to.

Comparing them with a placebo, they may help you lose 3–9 percent of your body weight [41]. Remember that this is only when these pills are combined with a healthy weight-loss diet. 

On their own, they are ineffective and unlikely to be helpful in the long run. They also have many possible side effects.

Among the 12 weight loss pills mentioned, the ones with the most substantial evidence are:

  • weight loss: glucomannan, CLA, and orlistat (Alli)
  • increased fat burning: caffeine and green tea extract

CLA, on the other hand, has harmful effects on metabolic health, which is why many health professionals advise against taking orlistat due to its unpleasant side effects.

Thus, we are left with caffeine, green tea extract and glucomannan. The effects of these supplements are modest at best, but they can be helpful. All three can be found naturally in foods and drinks without taking supplements.

In the end, no supplement or pill works very well for weight loss. A healthy weight, mindful eating, calorie deficits and stepping up your physical activity are still the most effective ways to lose weight and they work better than diet pills.

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[1] https://www.healthline.com/nutrition/12-weight-loss-pills-reviewed
[2] https://pubmed.ncbi.nlm.nih.gov/35032130/
[3] https://ods.od.nih.gov/HealthInformation/Ephedra.aspx
[4] https://www.ncbi.nlm.nih.gov/pubmed/21537493
[5] https://www.ncbi.nlm.nih.gov/pubmed/12672771
[6] https://pubmed.ncbi.nlm.nih.gov/28603504/
[7] https://pubmed.ncbi.nlm.nih.gov/27824614/
[8] https://pubmed.ncbi.nlm.nih.gov/30335479/
[9] https://www.ncbi.nlm.nih.gov/pubmed/8061728
[10] https://pubmed.ncbi.nlm.nih.gov/29401716/
[11] https://pubmed.ncbi.nlm.nih.gov/31270056/
[12] https://www.ncbi.nlm.nih.gov/pubmed/17490954
[13] https://www.ncbi.nlm.nih.gov/pubmed/21990002
[14] https://www.ncbi.nlm.nih.gov/pubmed/24520882
[15] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2129145/
[16] https://pubmed.ncbi.nlm.nih.gov/25732350/
[17] https://pubmed.ncbi.nlm.nih.gov/31984610/
[18] https://pubmed.ncbi.nlm.nih.gov/32951714/
[19] https://pubmed.ncbi.nlm.nih.gov/29802521/
[20] https://pubmed.ncbi.nlm.nih.gov/31772720/
[21] https://pubmed.ncbi.nlm.nih.gov/27486540/
[22] https://pubmed.ncbi.nlm.nih.gov/32962190/
[23] https://www.ncbi.nlm.nih.gov/pubmed/18006026
[24] https://pubmed.ncbi.nlm.nih.gov/31747468/
[25] https://pubmed.ncbi.nlm.nih.gov/30586587/
[26] https://pubmed.ncbi.nlm.nih.gov/26492494/
[27] https://www.ncbi.nlm.nih.gov/pubmed/16633129
[28] https://www.ncbi.nlm.nih.gov/pubmed/18842808
[29] https://pubmed.ncbi.nlm.nih.gov/33796302/
[30] https://pubmed.ncbi.nlm.nih.gov/30044398/
[31] https://pubmed.ncbi.nlm.nih.gov/30044398/
[32] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2943088
[33] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3368971/
[34] https://pubmed.ncbi.nlm.nih.gov/31643575/
[35] https://pubmed.ncbi.nlm.nih.gov/34307603/
[36] http://onlinelibrary.wiley.com/doi/10.1002/oby.20211/abstract
[37] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8078201/
[38] https://www.ncbi.nlm.nih.gov/pubmed/20025693
[39] http://archinte.jamanetwork.com/article.aspx?articleid=415539
[40] https://www.ncbi.nlm.nih.gov/pubmed/15862604
[41] http://jama.jamanetwork.com/article.aspx?articleid=1774038

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