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Top 12 effective weight loss pills & supplements

This is an in-depth, research-backed overview and review of the 12 most commonly used weight loss pills and supplements currently available.

Weight Management
This article is based on scientific evidence, written by experts, and fact-checked by experts.
We look at both sides of the argument and strive to be objective, unbiased, and honest.
Top 12 effective weight loss pills & supplements
Last updated on January 28, 2024, and last reviewed by an expert on September 20, 2023.

There are lots of ways people try to lose weight, and some methods are more popular than others. This includes various pills, medications, and natural supplements that promise to help you shed pounds or make it easier to do so when used with other approaches.

Top 12 effective weight loss pills & supplements

These products usually aim to help you in one of three ways:

It’s crucial to understand that not all of these options are backed by solid science, and some could even be harmful to your health. Always talk to a healthcare provider or a certified dietitian before making any changes to your diet or taking supplements.

To help you figure out what really works, here’s a rundown of 12 of the most talked-about weight loss pills and supplements, along with what the science says about them.

In this article

Weight loss pills and supplements

1. Garcinia cambogia extract

Garcinia cambogia gained fame after appearing on “The Dr. Oz Show” back in 2012.

This is a tiny, green, pumpkin-like fruit. The skin of the fruit is the source of its magic ingredient, hydroxycitric acid, which is what’s used in diet pills.

How it works

Tests on animals suggest that this extract might slow down the body’s fat-making process and lift your mood, which could help control food cravings.


A study that reviewed multiple other studies, called a meta-analysis, didn’t find much of a weight loss benefit when people took garcinia cambogia compared to a placebo.

A review from 2020 that looked at eight different trials concluded that people lost about 3 pounds on average when using garcinia cambogia.

Side effects

Most people consider garcinia cambogia safe when taken as directed. However, there have been some concerning reports. For example, a 2018 study highlighted four women who suffered acute liver failure after taking weight loss pills that included this extract.

Some people have also reported liver problems and episodes of extreme mood swings when using garcinia cambogia.

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Summary: While garcinia cambogia might lead to slight weight loss, the results are often too small to really make a difference. Be cautious of potential side effects, especially regarding liver health.

2. Hydroxycut

Hydroxycut has been on the market for over 10 years and is among the most well-known weight loss supplements globally.

The brand offers various products, with the most popular simply named “Hydroxycut.”

How it works

The supplement includes several ingredients touted to help you lose weight, such as caffeine and some plant-based extracts, including green coffee extract, which we’ll discuss shortly.


A 2011 research review of five clinical trials found that taking green coffee extract, a key component in Hydroxycut, led to an average weight loss of about 5.5 pounds compared to those taking a placebo.

Side effects

If you’re sensitive to caffeine, you might experience symptoms like nervousness, shaking, an upset stomach, diarrhea, and mood swings.

It’s worth noting that Hydroxycut products were pulled off the market twice—once for heart-related issues in 2004 and again for liver problems in 2009.

There have also been reports of acute liver damage linked to Hydroxycut use.

Summary: There isn’t a lot of extensive research on Hydroxycut, and there’s no information on its long-term effects. More studies are needed to confirm both its effectiveness and safety.

3. Green coffee bean extract

Green coffee beans are just unroasted coffee beans.

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They have two ingredients thought to aid weight loss: caffeine and chlorogenic acid.

How it works

Caffeine helps to boost the rate at which your body burns fat, and chlorogenic acid slows down how fast carbs break down in your digestive system.


A few human studies suggest that green coffee bean extract might indeed help with weight loss.

A comprehensive review of all the clinical trials on this extract found that it has a significant effect on reducing body weight.

Other benefits

This extract may also help lower blood sugar and blood pressure levels. Plus, it’s rich in antioxidants.

Side effects

Similar to other caffeine-containing products, it may lead to symptoms like jitters. The chlorogenic acid in it could cause diarrhea, and some folks might be allergic to the beans themselves.

Summary: Green coffee bean extract could help with modest weight loss. However, it’s worth noting that many of the studies supporting this claim are backed by the industry.

4. Caffeine

Caffeine is the most widely consumed psychoactive substance globally and is naturally found in various sources like coffee, green tea, and dark chocolate.

It is often added to commercial weight loss supplements due to its purported metabolism-boosting effects.

How it works

Research indicates that caffeine may contribute to weight loss by increasing energy expenditure—essentially, it helps you burn more calories. It can also promote fat breakdown and increase thermogenesis, the process by which your body generates heat.


Some human studies suggest that caffeine can contribute to modest weight loss, although results are not universally consistent.

Side effects

High caffeine consumption can lead to a range of symptoms, including anxiety, insomnia, jitteriness, irritability, nausea, and diarrhea. Caffeine is also addictive and can impair sleep quality.

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Rather than relying on supplements or pills, it’s better to get caffeine from natural sources like quality coffee and green tea, which offer additional health benefits like antioxidants.

Summary: While caffeine may help boost your metabolism and fat burning in the short term, you can quickly develop a tolerance to its effects.

5. Orlistat (Alli)

Orlistat is a medication available both over the counter as Alli and by prescription as Xenical.

How it works

Orlistat works by inhibiting the enzyme responsible for breaking down fats in your digestive system. As a result, less fat is absorbed, reducing the number of calories you take in.


A 2003 meta-analysis found that people using orlistat in conjunction with lifestyle changes experienced a 2.9% greater weight reduction compared to those using a placebo.

Other benefits

Orlistat has been shown to have a mild effect on reducing blood pressure and may lower the risk of type 2 diabetes when used in combination with lifestyle changes.

Side effects

Orlistat comes with a number of digestive side effects, including loose and oily stools, flatulence, and frequent, hard-to-control bowel movements. It may also lead to deficiencies in fat-soluble vitamins like A, D, E, and K.

It is often recommended to follow a low-fat diet while taking orlistat to minimize side effects. Interestingly, a low-carb diet has been shown to be as effective for weight loss as combining orlistat with a low-fat diet, without the unpleasant side effects.

Summary: Orlistat can reduce fat absorption, thereby aiding weight loss, but comes with several digestive side effects that can be unpleasant. Adopting a low-fat diet can help manage these side effects.

6. Raspberry ketones

Raspberry ketones are the compounds that give raspberries their unique scent.

A lab-made version of raspberry ketones is available as a weight loss aid.

How it works

When tested on fat cells from mice, raspberry ketones help break down fat and boost a hormone named adiponectin, which is thought to help with shedding pounds.


There’s limited research on how raspberry ketones work in people. One study from 2013 looked into raspberry ketones and some other substances, finding they might help people lose about 2% more weight in 8 weeks compared to a sugar pill.

In a study with mice, big doses seemed to slow down weight gain.

However, large amounts of raspberry ketones also led to elevated blood sugar and higher levels of a liver enzyme, signaling possible liver issues.

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It’s still unclear if these findings apply to humans. More studies are needed to figure out the pros and cons.

Side effects

Taking them might make your burps smell fruity, like raspberries.

Summary: There’s no solid proof to show that raspberry ketones help people lose weight. The studies on rats that did indicate some effectiveness used extremely high doses. More studies are required to make any definitive claims.

7. Glucomannan

Glucomannan is a fiber that comes from the root of the elephant yam, also known as konjac.

How it works

This fiber soaks up water and turns into a gel-like substance. It stays in your stomach, making you feel full and helping you eat less.


In one study, people who took glucomannan for two months lost some weight, but only if they kept taking the supplement regularly.

Other benefits

Glucomannan is more than just a weight-loss aid. It’s a fiber that nurtures the good bacteria in your gut. Plus, it can lower your blood sugar, cholesterol, and fats in the blood, and it’s a good remedy for constipation.

Side effects

It might make you feel bloated or gassy and produce softer stools. Also, it can mess with the effectiveness of some medicines you swallow.

To get the most benefit, it’s recommended to drink a glass of water about 30 minutes before eating when taking glucomannan.

Summary: Combining a healthy diet with glucomannan fiber can aid weight loss and improve health markers.

8. Meratrim

Meratrim is a fairly new addition to the world of diet pills.

It blends two plant extracts—Sphaeranthus indicus and Garcinia mangostana—that are thought to alter how fat cells work.

How it works

The supplement is said to make it more difficult for fat cells to grow, reduce the amount of fat they absorb from your blood, and encourage the burning of stored fat.


Not many studies on Meratrim are available. In one research project, 60 obese individuals were put on a strict 2,000-calorie diet and had their physical activity increased. They either received Meratrim or a sugar pill.

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After 8 weeks, those taking Meratrim lost 11 pounds and nearly 5 inches from their waist. Another study hinted at long-term effects on reducing hunger.

Side effects

No adverse effects have been reported so far.

Summary: One study found that Meratrim led to weight loss and offered additional health perks. However, it’s important to note that the research was funded by the industry, so we need more unbiased studies to confirm these findings.

9. Green tea extract

Green tea extract is commonly found in weight loss supplements because it contains an antioxidant called EGCG, which is believed to help burn fat.

How it works

The extract is thought to block certain enzymes like pancreatic lipase, making it harder for your body to absorb fat, thus potentially helping with weight loss.


Multiple studies indicate that, when combined with exercise, green tea extract can boost fat burning and lead to weight loss, especially around the belly.

Side effects

Green tea extract is usually well-accepted but contains some caffeine, which might affect people sensitive to it. The general health perks of drinking green tea should also apply to its extract.

Summary: Green tea and its extract might give your fat-burning ability a small boost and could specifically help you shed some belly fat.

10. Conjugated linoleic acid (CLA)

Conjugated linoleic acid has been a go-to fat-loss supplement for many years.

It’s seen as one of the “better” trans fats and naturally appears in fatty foods derived from animals like cheese and butter.

How it works

CLA claims to decrease your appetite, rev up your metabolism, and promote fat breakdown.


A comprehensive review of 13 studies showed that CLA led to a modest weight loss of roughly 1.1 pounds compared to a placebo. This went up to 2.3 pounds in people aged 44 and above. Another 2012 review questioned whether this small amount of weight loss is clinically significant.

Side effects

CLA might cause digestive issues and, over the long haul, could potentially contribute to conditions like fatty liver, insulin resistance, and inflammation.

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Summary: Conjugated linoleic acid might help you lose a small amount of weight, but it could also have negative long-term effects on your health. Given the risks, the minor weight loss benefits it offers probably aren’t worth it.

11. Forskolin

Forskolin is a plant extract from the mint family, commonly promoted as a weight loss supplement.

How it works

It’s believed to boost a cellular compound called cAMP, which may help in burning fat.


A study involving 30 overweight or obese men found that forskolin helped reduce body fat and increase muscle mass, but didn’t affect overall weight. Another study with 23 overweight women found no benefits.

Side effects

Information on its safety and potential side effects is scarce.

Summary: The limited research on forskolin has produced mixed outcomes, making its effectiveness uncertain. Until there’s more conclusive evidence, it’s a good idea to steer clear of this supplement.

12. Bitter orange/synephrine

Bitter orange, a specific type of orange, contains a compound known as synephrine.

This compound is similar to ephedrine, a once-popular ingredient in weight loss pills that was banned by the FDA due to severe side effects.

How it works

Though not as strong as ephedrine, synephrine may help curb your appetite and increase fat-burning activity.


Research on synephrine is limited, but ephedrine was shown to result in short-term weight loss in various studies.

Side effects

Synephrine could have serious heart-related side effects and may also be addictive.

Summary: Synephrine is a fairly strong stimulant that might help with short-term weight loss. However, it can have serious side effects, particularly related to heart health. Because of these risks, it’s essential to use synephrine very carefully and always under the guidance of a healthcare provider.

Prescription medications for weight loss

There are also some prescription medications for weight loss that have shown moderate effectiveness.

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Contrave and Phentermine are the most frequently prescribed ones.

A 2014 review suggests that even these prescription options may not be as effective as you’d think. On average, they could help you shed 3–9% of your body weight, but only when compared to a placebo.

It’s important to note that these pills only work when paired with a healthy diet geared towards weight loss. On their own, they won’t offer a sustainable solution to long-term weight issues and come with a range of possible side effects.


Among the 12 weight loss supplements we discussed, the ones with the most robust scientific support are:

However, many healthcare experts warn against using orlistat due to its uncomfortable side effects, and conjugated linoleic acid because it can negatively affect your metabolic health.

This leaves us with glucomannan, green tea extract, and caffeine. While these supplements can offer some benefits, their impact is generally small. Plus, you can find all three in natural foods and beverages, so you don’t necessarily need to take a supplement.

In the end, no pill or supplement is a magic solution for weight loss. They may offer a slight metabolic boost and help you shed a few pounds, but that’s about it.

The most effective ways to lose weight remain adopting a balanced diet, eating mindfully, creating a safe calorie deficit, and getting regular exercise. These approaches are far more effective than any weight loss pill on the market.

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