Popular Weight Loss Supplements and Pills

Reduced absorption of fat to limit your calorie intake.

There is countless of weight loss pills and supplements available on the interenet.

All claim to either help you lose weight, or are combined with other methods to make weight loss easier and all use one or more of the following mechanisms:

  1. Reduced absorption of fat to limit your calorie intake.
  2. Reduced appetite to make you feel fuller so that you consume less calories.
  3. Increased fat burning helping you burn more calories.

The list below discusses 12 of the most popular weight loss supplements and pills, including scientific research done on them.


caffine supplement

Caffeine is the psychoactive substance that is consumed most in the world (6).

Found naturally in coffee, dark chocolate and green tea, caffeine is also added to many processed beverages and foods.

Caffeine is often added to commercial weight loss supplements as its metabolism boosting capabilities are well known.

How it works: Short-term studies indicate that caffeine increases fat burning by up to 29% and boosts metabolism by between 3 and 11% (1 , 2 , 3 , 4).

Effectiveness: Some studies show that caffeine could cause modest weight loss in humans (5 , 6).

Side effects: Caffeine is addictive and could reduce sleep quality. In some instances, high dosages of caffeine could cause insomnia, anxiety, irritability, jitteriness, diarrhea, nausea and various other symptoms.

It is not necessary to take supplements or pills containing caffeine, as caffeine occurs naturally in green tea and coffee. Green tea also contain antioxidants and has other health benefits.

Bottom Line: Although caffeine could enhance fat burning and boost metabolism in the short term, tolerance to these effects tends to develop quickly.

Garcinia Cambogia Extract

Garcinia Cambogia Extract supplement

In 2012, garcinia cambogia was discussed on the Dr. Oz show and became popular internationally as a result.

It is a small, green fruit shaped like a pumpkin.

The skin of garcinia cambogia holds hydroxycitric acid (HCA), which is the active ingredient in garcinia cambogia extract. This extract is marketed as a diet pill.

How it works: Animal studies have shown that garcinia cambogia extract can increase serotonin levels and inhibit a specific fat-producing enzyme. This could potentially help to reduce cravings (7, 8).

Effectiveness: In a study in which 130 people participated, garcinia was compared to a placebo. There was no difference in body fat percentage or weight loss between the groups ( 9).

In 2011, a review looked at 12 studies on garcinia cambogia and found that it caused an average loss of weight of 0.88 kg (2 pounds) over several weeks ( 10).

Side effects: No serious side effects have been reported, although some reports indicate small digestive problems.

Bottom Line : Although garcinia cambogia could result in modest weight loss, the effects are so small that it's probably not worthwhile going this route.

Raspberry Ketones

Raspberry Ketones supplement

As the name indicates, raspberries contain raspberry ketone. This substance causes their distinct smell.

Synthetically produced raspberry ketones is available as a weight loss supplement.

How it works: Raspberry ketones increased the breakdown of fat and increased adiponectin levels in fat cells isolated from rats. Adiponectin is a hormone associated with weight loss (11).

Effectiveness: There are no studies on the effects of raspberry ketones in humans. One rat study showed that they reduced weight when massive doses were used (12).

Side effects: Your burps might smell like raspberries.

Bottom Line : There is no evidence to suggest that raspberry ketones could cause weight loss in humans, and the rat study only worked with massive doses.


Orlistat pills

Orlistat is a pharmaceutical drug, sold under prescription as Xenical and over-the-counter as Alli.

How it works : This pill inhibits the breakdown of fat in the gut, reducing your calorie intake from fat.

Effectiveness: According to a review done of 11 studies, orlistat can cause weight loss of 2.7 kg (6 pounds) when compared to a placebo (13).

Other benefits: Orlistat has been linked to a slight reduction in blood pressure, and one study showed that it reduced the risk of developing type 2 diabetes by 37% (14 , 15).

Side effects: This drug has a number of side effects, mainly relating to the digestive system. These include flatulence, loose, oily stools, frequent bowel movements and others. It may also contribute to a fat-soluble vitamin deficiency, such as vitamins A, D, E and K.

In order to minimize side effects, it is normally recommended that a low-fat diet be followed while using the drug.

Interestingly, it has been shown that a low carb diet without drugs is as effective as a low-fat diet combined with orlistat (16).

Bottom Line : Orlistat can reduce the amount of fat absorbed from food and help with weight loss. Some of its many side effects are highly unpleasant.



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

How it works: When glucomannan absorbs water, it becomes like a gel which stays in the gut, promoting a feeling of fullness. This helps by you eating fewer calories (17).

Effectiveness: Three independent studies done on human show that when glucomannan is used in combination with a healthy diet, it could result in a weight loss of 3.6 to 4.5 kg (8 to10 pounds) in 5 weeks (18).

Other benefits: Glucomannan feeds the "good" bacteria in the intestine. It also lowers blood sugar and cholesterol, and triglycerides. Glucomannan is also very effective in preventing constipation (19 , 20 , 21).

Side effects: Glucomannan can lead to bloating, flatulence, and soft stools. It could also interfere with various oral medication if these are taken at the same time.

Glucomannan should be taken with a glass of water about 30 minutes before meals.

Bottom Line : Various studies show that when glucomannan fiber is taken in conjunction with a healthy diet, it helps people lose weight. It can also lead to an improvement of various health markers.

Green Coffee Bean Extract

green coffee beans

Coffee beans that aren't roasted are known as green coffee beans.

They contain caffeine and chlorogenic acid, both of which are believed to assist with weight loss.

How it works: Chlorogenic acid reduces the breaking down of carbohydrates in the gut, while caffeine increases fat burning.

Effectiveness: Various studies involving human have demonstrated that it can assist with weight loss (22 , 23).

A review of three studies determined that the supplement made people lose 2.5 kg (5.4 lbs.) more when compared to a group using a placebo ( 24).

Other benefits: It may also lower blood sugar levels and reduce blood pressure. It also contains high levels of antioxidants (25 , 26 , 27 , 28).

Side effects: Green coffee bean extract has similar side effects to caffeine. Diarrhea could be caused by the chlorogenic acid, while some may be allergic to green coffee beans (29).

Bottom Line : Green coffee bean extract could assist with modest weight loss. It should however be noted that many of the studies were sponsored by industry.

Green Tea Extract

green tea extract

Green tea extract is widely used in weight loss supplements as numerous studies have indicated that its main antioxidant, EGCG, aids in burning fat.

How it works: It is believed that green tea extract increases the activity of norepinephrine, a fat burning hormone (30).

Effectiveness: Various human studies show that green tea extract increases fat burning and causes fat loss, especially belly fat (31 , 32 , 33 , 34).

Side effects: Green tea generally does not present with side effects. It does however contain caffeine in small amounts and this could cause symptoms in caffeine sensitive people.

The health benefits of drinking green tea are also applicable to green tea extract.

Bottom Line : Green tea extract and green tea can both increase fat burning to a limited degree, and could help you lose belly fat.

Conjugated Linoleic Acid (CLA)

CLA capsules

Conjugated linoleic acid (CLA), has been used as a fat loss supplement for many years.

It is a "healthy" trans fat that is found naturally in fatty animal foods such as butter and cheese .

How it works : CLA boosts metabolism, reduces appetite and stimulates body fat breakdown ( 35 , 36).

Effectiveness: When 18 different studies were reviewed, CLA was found to cause weight loss of about 0.1 kg (0.2 lbs.) per week for up to six months (37).

Another review study done in 2012 showed that CLA helped people lose about 1.3 kg (3 lbs.) when compared to a placebo (38).

Side effects: CLA could result in various digestive side effects. It may also have harmful effects over time, potentially contributing to insulin resistance, fatty liver, and increased inflammation.

Bottom Line : CLA can be an effective weight loss supplement, but could have harmful effects in the long term. The small weight loss that could be achieved is not worth the risk.


Forskolin supplement

An extract from a plant in the mint family, forskolin is believed to be an effective aid for weight loss.

How it works: It is thought that it raises levels of cAMP, a compound found inside its cells. This may stimulate the burning of fat (39).

Effectiveness: A study in which 30 obese and overweight men participated showed that forskolin increased muscle mass and reduced body fat, ultimately having no effect on body weight. However, in another study on 23 overweight women, no effects were found ( 40 , 41).

Side effects: Limited data on the safety of this supplement or any of its side effects is available.

Bottom Line : The two small studies done show conflicting results. Avoid this supplement until more is known.


Meratrim supplement

Meratrim combines of two plant extracts that could affect the metabolism of fat cells and is a newcomer to the diet pill market

How it works: It is believed that meratrim makes it difficult for fat cells to multiply, decreases the amount of fat that is absorbed from the bloodstream, and helps burn stored fat.

Effectiveness: Only one study has been conducted on Meratrim. 100 obese people were placed on a strict diet of 2000 calorie, supplemented with either Meratrim or a placebo ( 42).

After 8 weeks, the Meratrim group had lost 11 lbs. (5.2 kg) of weight and showed a 4.7 inches (11.9 cm) reduction in waistline. Quality of life had also improved, while cholesterol, blood sugar and triglycerides were all reduced.

Side effects: No known side effects.

Bottom Line : The single study demonstrated that Meratrim assisted with weight loss and introduced a number of other health benefits. The study was however industry sponsored and more research should be done.

Bitter Orange / Synephrine

Bitter Orange

The so-called bitter orange contains synephrine, which is related to ephedrine, previously a common ingredient in numerous weight loss pill formulations.

Ephedrine has however been banned by the FDA due to serious side effects.

How it works: Synephrine has a mechanism similar to ephedrine, but it is not as potent. It reduces appetite and increases fat burning significantly (43).

Effectiveness: Not many studies have been done on synephrine, but it has been shown that ephedrine causes significant short-term weight loss (44).

Side effects: Synephrine could have serious heart related side effects, similar to those of ephedrine. It may also be addictive.

Bottom Line : Synephrine is fairly potent and possibly effective for weight loss in the short term. As the side effects could be serious, it should only be used with extreme caution.

Skinny Piggies - Fiber Gummies

fiber gummies

Skinny Piggies are popular gummy dietary supplements that contain multiple ingredients to target hunger suppression and weight loss. One gummy should be taken 30 minutes before eating a meal.

How it works: It contains Inulin fiber that expands into a gel in the digestive tract and absorbs water and curbs appetite (45). In addition, it boosts appetite suppressing serotonin by 5-HTP (46, 47) and modulates food intake by chromium picolinate (48).

Effectiveness: Clinical trials performed on the key ingredients inulin, 5-HTP and chromium picolinate, have shown reduced appetite and craving (49, 50), and resulted in weight loss (51, 52).

Side effects: As with any fiber, some people may experience some flatulence (gas) when first taking the supplement until the body gets used to the fiber.

Bottom Line : Skinny Piggies have only minimal side effects and contain ingredients that have been shown in human clinical studies to curb appetite, lower caloric intake and result in weight loss.

How Skinny Piggies Appetite Suppressant Gummies work