There are many possible solutions to losing weight.
Some options are more popular than others, including certain pills, medications, and natural supplements. These claim to help you lose weight or at least make it easier if you combine them with other methods.
They usually work through one or more of these mechanisms:
- They reduce appetite and provide a better feeling of satiety so you eat fewer calories
- Reducing the absorption of nutrients like fat, causing you to consume fewer calories
- Boost fat burning and makes you burn more calories
It’s important to realize that few of these treatments have any scientific basis, and some can have serious health consequences. You should always discuss any changes in your diet or supplements with a doctor or a nutritionist.
To separate the myths from the facts, here are the 12 most popular weight loss pills and supplements that are backed by science.
Weight loss pills and supplements
1. Garcinia cambogia extract
Garcinia cambogia became popular around the world after it was featured in The Dr. Oz Show” was introduced.
It is a small, green fruit shaped like a pumpkin. The skin of the fruit contains hydroxycitric acid, the active ingredient in garcinia cambogia extract, which is marketed as a diet pill.
How it works: Animal studies show that it can hinder a fat-producing enzyme in the body and increase serotonin levels, potentially helping reduce cravings ( 1 , 2 ).
Effectiveness: In a meta-analysis, researchers examined four electronic research databases to examine the effectiveness of herbal medicines, including Garcinia cambogia.
In a total of 54 randomized controlled trials in healthy adults who were overweight or obese, the authors found no difference in weight or body fat percentage between the garcinia cambogia group and the placebo group ( 3 ).
Side Effects: While it is widely agreed that taking Garcinia cambogia in recommended amounts is safe, studies over the past few years have pointed to some serious side effects.
A 2018 study documents four cases of women who experienced acute liver failure after taking Garcinia cambogia-containing supplements ( 5 ).
In addition, hepatotoxicity, i.e. liver damage, and some episodes of mania have also been reported in connection with the intake of Garcinia cambogia ( 6 , 7 ).
While Garcinia cambogia can contribute to modest weight loss, the effects are quite minor and may not be noticeable.
2. Hydroxycut
Hydroxycut has been around for more than a decade and is one of the most popular weight loss supplements around.
The brand makes several products, but the most well-known is simply called “Hydroxycut”.
How it works: It contains several ingredients that are said to help with weight loss, including caffeine and some plant extracts like Green Coffee Extract, which we’ll get to in more detail later
Effectiveness: A 2011 meta-analysis of five clinical trials found that taking C. canephora robusta or green coffee extract, a key ingredient in Hydroxycut, resulted in a weight loss of about 5 pounds (2.47 kg) compared to placebo ( 5.5 pounds) led ( 8 ).
Side effects: If you are sensitive to caffeine, you may experience anxiety, nervousness, tremors, nausea, diarrhea, and irritability ( 9 ).
Hydroxycut products were pulled off shelves in 2004 for cardiovascular risks and in 2009 for hepatotoxicity ( 10 ).
Acute liver damage has also been associated with taking Hydroxycut supplements ( 11 ).
There are few large-scale studies of this dietary supplement and no data on its long-term effectiveness. More research is needed to determine its effectiveness and safety concerns.
3. Green coffee bean extract
Green coffee beans are simply coffee beans that have not yet been roasted.
They contain two substances that are believed to help with weight loss: caffeine and chlorogenic acid.
How it works: Caffeine can boost fat burning, and chlorogenic acid can slow the breakdown of carbohydrates in the gut.
Efficacy: Several human studies have shown that green coffee bean extract can help people lose weight ( 12 , 13 ).
Other Benefits: Green coffee bean extract may help lower blood sugar levels and reduce blood pressure. It’s also high in antioxidants ( 15 , 16 , 17 , 18 ).
Side Effects: It can cause the same side effects as caffeine. The chlorogenic acid it contains can also cause diarrhea, and some people may be allergic to green coffee beans ( 19 ).
Green coffee bean extract may provide modest weight loss, but keep in mind that many of the studies that have found this were industry sponsored.
4. Caffeine
Caffeine is the most commonly consumed psychoactive substance in the world ( 20 ).
It’s found naturally in coffee, green tea, and dark chocolate, and is added to many processed foods and beverages.
Because caffeine is considered a metabolism booster, companies often add it to commercial weight loss supplements.
How it works: One study discussed caffeine’s effect on regulating body weight by increasing energy expenditure — which essentially means you burn more calories through increased fat breakdown as well as through a body heat production process called thermogenesis ( 21 ).
Effectiveness: Some studies show that caffeine can lead to modest weight loss in humans ( 22 , 23 ).
Side Effects: In some people, high amounts of caffeine can cause anxiety, insomnia, nervousness, irritability, nausea, diarrhea, and other symptoms. Caffeine is also addictive and can affect the quality of your sleep ( 24 ).
There is no need to take a supplement or caffeinated pill. The best sources are high-quality coffee and green tea , which also have antioxidants and other health benefits ( 25 ).
Caffeine can boost metabolism and increase fat burning in the short term. However, tolerance to the effects can quickly develop.
5. Orlistat (Alli)
Orlistat is a drug that is available over-the-counter under the name Alli and prescription under the name Xenical.
How it works: This weight loss pill works by inhibiting the breakdown of fat in your gut, which means you absorb fewer calories from fat.
Effectiveness: A 2003 meta-analysis of studies found that people who took orlistat for 12 months in combination with lifestyle changes lost 2.9% more weight than the placebo group ( 26 ).
Other benefits: Orlistat has been shown to slightly lower blood pressure and may reduce the risk of developing type 2 diabetes when taken along with lifestyle changes ( 27 , 28 ).
Side Effects: This drug has many digestive side effects, such as loose, oily stools, gas, and frequent bowel movements that are difficult to control. It can also contribute to deficiencies in fat-soluble vitamins like vitamins A, D, E, and K ( 29 ).
To minimize side effects, it is often recommended to follow a low-fat diet while taking orlistat. Interestingly, a low-carb diet (without medication) is thought to be just as effective as orlistat and a low-fat diet combined.
Both diets were equally effective for weight loss but showed no significant differences in blood sugar and blood lipid levels. However, orlistat was more effective in lowering blood pressure when combined with a low-fat diet ( 30 ).
Orlistat, also known as Alli or Xenical, can reduce the amount of fat you absorb from food and help you lose weight. It has many side effects, some of which are very uncomfortable.
6. Raspberry Ketones
Raspberry ketone is a substance found in raspberries and is responsible for their distinctive smell.
A synthetic version of the raspberry ketones is sold as a weight loss supplement.
How it works: In isolated mouse fat cells, raspberry ketones increase fat breakdown and increase levels of the hormone adiponectin, which is thought to be related to weight loss ( 32 ).
Effectiveness: There are very few human studies of raspberry ketones, but a 2013 study looked at raspberry ketones along with some other ingredients and found a possible 2% increase in weight loss over 8 weeks compared to a placebo ( 31 ).
A study in mice with massive doses showed some delay in weight gain ( 32 ).
However, high doses of raspberry ketone have also been associated with higher blood sugar levels and higher levels of the liver enzyme ALT, indicating liver dysfunction.
It is not known whether these effects translate to humans. Further research is needed to determine benefits and risks.
Side Effects: They can make your burp smell like raspberries.
There is no evidence that raspberry ketones cause weight loss in humans, and high doses have been used in the rat studies that suggest they might work. More research is needed.
7. Glucomannan
Glucomannan is a type of fiber found in the roots of elephant yam, also known as konjac.
How it works: Glucomannan absorbs water and becomes gel-like. It “lodges” in your gut and promotes feelings of fullness, causing you to consume fewer calories ( 33 ).
Effectiveness: A clinical study showed that taking glucomannan for 60 days could reduce body weight in overweight participants, but only if they took the supplement consistently ( 34 ).
Other Benefits: Glucomannan is a dietary fiber that can feed the friendly bacteria in your gut. It can also lower blood sugar, cholesterol, and triglycerides, and is effective against constipation ( 35 , 36 , 37 ).
Side effects: Es kann zu Blähungen, Blähungen und weichem Stuhl führen und kann bei gleichzeitiger Einnahme mit einigen oralen Medikamenten in Konflikt geraten.
It is important to take glucomannan with a glass of water about half an hour before meals.
Studies show that the dietary fiber glucomannan can help with weight loss when combined with a healthy diet. It also leads to improvements in various health markers.
8. Meratrim
Meratrim is a relative newcomer to the diet pill market.
It is a combination of two plant extracts – Sphaeranthus indicus and Garcinia mangostana – which can alter the metabolism of fat cells.
How it works: It claims that it makes it harder for fat cells to multiply, decreases the amount of fat they absorb from the bloodstream, and helps them burn stored fat.
Efficacy: There are very few studies on Meratrim. In one study, 60 obese people were put on a strict 2,000-calorie diet and encouraged to be more physically active, receiving either Meratrim or a placebo.
After 8 weeks, the Meratrim group had lost 11 pounds (5.2 kg) and 11.9 cm (4.7 inches) in waist circumference ( 38 ).
Another study suggests that Meratrim has long-lasting appetite suppressant effects ( 39 ).
Side Effects: No side effects have been reported.
A study has shown that Meratrim causes weight loss and has a number of other health benefits. However, the study was sponsored by industry and more research is needed.
9. Green Tea Extract
Green tea extract is a popular ingredient in many weight loss supplements. This is because numerous studies have shown that the main antioxidant EGCG it contains can promote fat burning.
How it works: Green tea extract is thought to inhibit enzymes such as pancreatic lipase, which when coupled with reduced fat intake can be an effective way to treat obesity ( 40 ).
Effectiveness: Many human studies have shown that green tea extract combined with exercise can boost fat burning and lead to fat loss, especially in the abdominal area ( 41 , 42 , 43 , 44 ).
All of the health benefits of green tea also apply to green tea extract .
Green tea and green tea extract could slightly increase fat burning and help you lose belly fat.
10. Conjugated Linoleic Acid (CLA)
CLA has been a popular fat loss supplement for years.
Known as one of the “healthier” trans fats, it’s found naturally in some high-fat animal foods like cheese and butter.
How it works: CLA may reduce appetite, increase metabolism, and stimulate the breakdown of body fat ( 45 , 46 ).
Effectiveness: In a large review of 13 studies, researchers found that CLA caused about 1.1 pounds (0.52 kg) of weight loss compared to a placebo. In people over the age of 44, that number rose to 2.3 pounds (1.05 kg) ( 47 ).
According to another study from 2012, CLA can lead to a weight loss of about 0.7 kg compared to a placebo. The authors question the clinical relevance of the small effect of CLA on body weight ( 48 ).
Side Effects: CLA can cause various digestive side effects and long-term harmful effects that may contribute to fatty liver, insulin resistance, and increased inflammation.
CLA could be an effective weight loss tool, but it can have harmful effects in the long run. The small amount of weight loss it may cause is not worth the risk.
11. Forskolin
Forskolin is an extract from a plant in the mint family that is believed to aid in weight loss.
How it works: It may increase levels of a compound in cells called cAMP, which may stimulate fat burning ( 49 ).
Side Effects: There is little data on the safety of this dietary supplement or the risk of side effects.
The two small studies on forskolin have shown conflicting results. It is best to avoid this supplement until more research is done.
12. Bitter Orange/Synephrine
A type of orange called bitter orange contains the compound synephrine.
Synephrine is related to ephedrine, which used to be a popular ingredient in various weight loss pills ( 52 ).
However, the FDA has since banned ephedrine as a weight-loss drug due to serious side effects ( 53 ).
How it works: Synephrine has similar mechanisms of action as ephedrine but is less potent. It might help reduce appetite and increase fat burning ( 54 ).
Effectiveness: There are very few studies on synephrine, but many studies have found that ephedrine can lead to significant weight loss in the short term ( 55 ).
Side Effects: Like ephedrine, synephrine can have serious heart-related side effects. It can also be addictive.
Synephrine is a fairly powerful stimulant and can help with weight loss in the short term. However, the side effects can be serious, so it should only be taken with extreme caution and under medical supervision.
Prescription drugs for weight loss
Also, some prescription weight loss pills have been shown to be reasonably effective.
The most common of these are Contrave and Phentermine.
According to a 2014 study, even prescription weight loss pills don’t work as well as you might think. On average, they can help you lose 3-9% of your body weight compared to a placebo ( 56 ).
Keep in mind that this only applies when these pills are combined with a healthy weight loss diet. On their own, they are ineffective and not a good solution to obesity in the long run. Also, they have many potential side effects.
Conclusion
Of the 12 weight loss pills mentioned, the ones with the strongest evidence are the following:
- Weight Loss: Glucomannan, CLA, and Orlistat (Alli)
- increased fat burning: caffeine and green tea extract
However, many health experts advise against orlistat because of its unpleasant side effects and CLA because of its harmful effects on metabolic health.
That leaves glucomannan, green tea extract and caffeine. These supplements can be helpful, but the effects are modest at best. And you can find all three naturally in foods and beverages without resorting to supplements.
Ultimately, no dietary supplement or pill works particularly well for weight loss. They can boost your metabolism a bit and help you shed a few pounds, but that’s where their effects stop.
Finding a healthy weight for you , mindful eating, a safe calorie deficit , and increased physical activity are still the best methods for losing weight, and these methods work better than all the diet pills combined.