A closer look at popular diet supplements
There are many different weight loss solutions on the market. This includes a variety of pills, medications and natural supplements. All of these products claim to be able to help you lose weight or at least make weight loss easier in combination with other methods.
These products usually work through one or more of the following mechanisms:
- Reduction in appetite, making you feel fuller, which results in you eating fewer calories.
- Reduced absorption of nutrients such as fat or carbohydrates, allowing your body to utilize fewer calories
- Increased fat burning, allowing you to burn more calories Here is a selection of the most popular fat loss products and supplements and their scientific reviews:
Garcinia Cambogia Extract
Garcinia Cambogia became world famous in 2012 after it was featured on a popular American television program.
This product is a small green fruit shaped like a pumpkin. The skin of this fruit contains hydroxycitric acid (HCA), which is the active ingredient marketed as a diet aid.
How does Garcinia Cambogia extract work?
Research conducted on animals shows that it can inhibit the fat-producing enzyme in the body while increasing serotonin levels, which can potentially reduce hunger and cravings (1, 2). In addition, there is evidence that the hydroxycitric acid it contains can stabilize blood sugar levels and counteract sharp fluctuations in insulin and blood sugar levels.
How effective is Garcinia Cambogia extract?
The scientific study situation is mixed. While a study of 130 subjects found no difference between a placebo and a Garcinia Cambogia extract in terms of body weight and body fat percentage between the groups, a review of 12 studies concluded that Garcinia Cambogia extracts caused a significant weight loss of 2 pounds on average over the course of the study (3, 4).
Potential side effects: There are no reports of serious side effects, only isolated reports of mild digestive problems.
Hydroxycut
Hydroxycut is one of the best known weight loss products and has been successfully marketed in various formulas for over a decade.
How does Hydroxycut work?
Depending on the formula, Hydroxycut contains a mixture of several ingredients, including caffeine and various plant extracts, which are intended to promote weight loss via different mechanisms.
How effective is Hydroxycut?
One study found that the then-current version of Hydroxycut resulted in a weight loss of 21 pounds within 3 months, which is quite a lot compared to other products (5). However, it should be kept in mind that the formula of the product has changed several times over the years.
Potential side effects: People who are sensitive to caffeine may experience side effects such as restlessness, tremors, nausea, diarrhea and irritability.
Caffeine
Caffeine is the most commonly consumed psychoactive substance in the world. It occurs naturally in coffee, green tea and dark chocolate and is added to many processed foods and drinks. In addition, caffeine is an integral part of many weight loss products as it can stimulate the metabolism and thus increase calorie consumption.
How does caffeine work?
Studies have shown that caffeine can temporarily increase the metabolic rate by 3 to 11% and increase fat burning by up to 29% (6, 7). In addition, it causes a preferential use of fat for the purpose of energizing the body.
How effective is caffeine?
A number of human studies have shown that caffeine can cause moderate weight loss (8, 9).
Potential side effects: In some people, caffeine in large amounts can cause side effects such as restlessness, tremors, nausea, diarrhea and irritability. Caffeine can also be addictive and reduce sleep quality. In addition to this, a habituation effect occurs over time, which reduces its effectiveness.
Optimal sources of caffeine: Caffeine does not necessarily have to be taken in the form of pure caffeine in tablet form or in the form of other caffeine supplements. The best sources are coffee and green tea, which are also rich in antioxidants and have other health benefits.
Orlistat (Alli)
Orlistat is an over-the-counter medication marketed under the name Alli.
How does orlistat work?
Orlistat works by inhibiting the breakdown of fat into fatty acids in the digestive tract, resulting in 20 to 25% of the fat consumed being excreted undigested.
How effective is Orlistat?
According to a large-scale study review of 11 human studies, orlistat increased weight loss by 6 pounds during the study period compared to a placebo (10).
In addition, orlistat has been shown to slightly lower blood pressure and reduce the risk of developing type 2 diabetes by 37% (11, 12).
Potential side effects: Orlistat may have some side effects, which include soft stools, oily stools, bloating, frequent bowel movements that are difficult to control, and others. It may also contribute to a deficiency of fat-soluble vitamins such as vitamins A, D, E and K. It is often recommended to use orlistat in combination with a low-fat diet to minimize side effects.
Interestingly, it has been shown that a low-carbohydrate diet (without medication) is just as effective as a combination of orlistat with a low-fat diet (13).
Raspberry ketones
Raspberry ketones are a substance found in raspberries and are responsible for their characteristic odor. A synthetic version of bilberry ketones is marketed as a weight loss supplement.
How do bilberry ketones work?
In isolated rat cells, raspberry ketones increase the breakdown of fat and increase levels of the hormone adiponectin, which is associated with weight loss (14).
How effective are bilberry ketones?
No human studies have yet investigated the effects of bilberry ketones in humans, but a study conducted with rats and relatively high doses of these ketones showed that they reduced weight gain (15).
Potential side effects: Blueberry ketones can cause belching with a blueberry odor.
Green coffee bean extract
Green coffee beans are nothing more than normal coffee beans that have not been roasted. They contain two substances that are believed to aid weight loss: Caffeine and chlorogenic acid.
How does green coffee bean extract work?
Caffeine can help increase fat burning and chlorogenic acid can slow down the breakdown of carbohydrates in the digestive tract.
How effective is green coffee bean extract?
Several studies have shown that green coffee bean extract can support weight loss (16, 17).
A review of 3 studies found that subjects who used green coffee bean extract lost an average of 5.4 pounds more weight over the course of the study compared to subjects who received only a placebo (18).
Green coffee bean extract can also help lower blood sugar levels and lower blood pressure. It is also rich in antioxidants (19, 20, 21).
Potential side effects: Green coffee bean extract can cause the same side effects as caffeine. The chlorogenic acid it contains can also cause diarrhea and some people are allergic to green coffee beans.
Glucomannan
Glucomannan is a dietary fiber found in the root of the konjac plant.
How does glucomannan work?
Glucomannan absorbs water and forms a kind of gel in the stomach, which fills the stomach. By filling the stomach, it promotes a feeling of satiety and helps to reduce calorie intake (22).
How effective is glucomannan
Three human studies found that glucomannan, in combination with a healthy diet, can help you lose 8 to 10 pounds in 5 weeks (23).
In addition, glucomannan is a healthy dietary fiber that feeds good gut bacteria and promotes their growth. Glucomannan can also lower blood pressure, cholesterol and triglyceride levels in the blood and helps with constipation (24, 25).
Glucomannan should be consumed about 30 minutes before meals with a glass of water.
Potential side effects: Glucomannan can cause a bloated feeling, flatulence and soft stools and can also interfere with the absorption of some medications if taken at the same time.
8 Meratrim
Meratrim is a relatively new dietary product. It is a combination of two plant extracts designed to change the metabolism of fat cells.
How does Meratrim work?
According to the manufacturer, Meratrim is designed to make it harder for fat cells to multiply, reduce the amount of fat that fat cells absorb from the bloodstream and help burn stored fat.
How effective is Meratrim?
To date, only one trial of Meratrim has been conducted, in which 100 obese volunteers were given either Meratrim or a placebo and followed a strict 2000 kcal diet (26).
After 8 weeks, the Meratrim group had lost 11 pounds in weight and 11.9 cm in waist circumference. In addition, their subjective quality of life had improved, while their blood glucose, cholesterol and triglyceride levels had decreased.
Potential side effects: No side effects are known to date.
Green tea extract
Green tea extract is a popular ingredient in many weight loss supplements. This is because studies have shown that the primary antioxidant it contains - EGCG - supports fat burning.
How does green tea extract work?
Green tea extract is believed to increase the activity of norepinephrine - a hormone that helps burn fat (27).
How effective are green tea extracts?
Numerous studies have shown that green tea extract can increase fat burning and cause fat loss - especially in the abdominal area (28, 29). All the positive effects of green tea extract are of course also present in green tea.
Potential side effects: Green tea extract is generally well tolerated. However, it does contain some caffeine and may cause side effects in people who are sensitive to caffeine.
Conjugated linoleic acid (CLA)
Conjugated linoleic acid has been a popular fat loss supplement for many years. It is one of the healthier trans fats and occurs naturally in some animal foods such as butter and cheese.
How does CLA work?
Conjugated linoleic acid can reduce appetite, boost metabolism and stimulate the breakdown of body fat (30, 31).
How effective is CLA?
In a review of 18 scientific studies, conjugated linoleic acid caused weight loss of 0.2 pounds per week over a period of up to 6 months (32).
According to another study review from 2012, CLA was able to produce a weight loss of about 3 pounds compared to a placebo (33).
Potential side effects: Conjugated linoleic acid can cause various digestive discomforts and could contribute to fatty liver, insulin resistance and increased inflammation in the long term.
Forskolin
Forskolin is an extract from a plant in the mint family that is claimed to be effective for weight loss.
How does forskolin work?
Forskolin is believed to increase the levels of a compound called cAMP in cells, which can stimulate fat burning (34).
How effective is forskolin?
A study of 30 overweight and obese men showed that forskolin reduced body fat and increased muscle mass without changing body weight (35). Another study with 23 overweight women, however, did not observe any effects (36).
Potential side effects: No data on risks or side effects are available.
Prescription drugs
In addition to the active ingredients and products described, there are a number of prescription diet medications.
However, according to a 2014 study, even prescription diet drugs are not as effective as many would like. On average, they can help you lose 3 to 9% of your body weight compared to a placebo (37).
However, this is only true when they are combined with a healthy weight loss diet. On their own, they are ineffective and are not a real solution to obesity. Not to mention the many possible side effects.
Take Home Message
Of the active ingredients described here, the following are the clear winners with the best scientific background:
- Weight loss: Glucomannan,CLA and Orlistat (Alli)
- Increased fat burning: caffeine and green tea extract
These supplements can be useful, although reducing carbohydrates and increasing protein intake are still the best options. However, these dietary strategies may work better in combination with supplements, which can give your metabolism a bit of a boost and help shed a few extra pounds.
References:
- http://www.jbc.org/content/246/3/629.long
- https://www.ncbi.nlm.nih.gov/pubmed/12349913
- http://jama.jamanetwork.com/article.aspx?articleid=188147
- http://www.hindawi.com/journals/jobes/2011/509038/
- http://benthamopen.com/contents/pdf/TOALTMEDJ/TOALTMEDJ-2-1.pdf
- https://www.ncbi.nlm.nih.gov/pubmed/2912010
- https://www.ncbi.nlm.nih.gov/pubmed/7486839
- https://www.ncbi.nlm.nih.gov/pubmed/8061728
- https://www.ncbi.nlm.nih.gov/pubmed/16076989
- https://www.ncbi.nlm.nih.gov/pubmed/15266516
- https://www.ncbi.nlm.nih.gov/pubmed/20025693
- https://www.ncbi.nlm.nih.gov/pubmed/14693982
- http://archinte.jamanetwork.com/article.aspx?articleid=415539
- https://www.ncbi.nlm.nih.gov/pubmed/20425690
- https://www.ncbi.nlm.nih.gov/pubmed/15862604
- https://www.ncbi.nlm.nih.gov/pubmed/22291473
- https://www.ncbi.nlm.nih.gov/pubmed/18035001
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2943088/
- https://www.ncbi.nlm.nih.gov/pubmed/9003513/
- https://www.ncbi.nlm.nih.gov/pubmed/11924733
- https://www.ncbi.nlm.nih.gov/pubmed/20933071
- http://jn.nutrition.org/content/130/2/272S.full
- https://www.ncbi.nlm.nih.gov/pubmed/1561420
- https://www.ncbi.nlm.nih.gov/pubmed/16633129
- https://www.ncbi.nlm.nih.gov/pubmed/18842808
- http://onlinelibrary.wiley.com/doi/10.1002/oby.20211/abstract
- http://www.sciencedirect.com/science/article/pii/S0031938410000703
- https://www.ncbi.nlm.nih.gov/pubmed/18006026
- https://www.ncbi.nlm.nih.gov/pubmed/17882140
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2826589/
- https://www.ncbi.nlm.nih.gov/pubmed/11316347
- https://www.ncbi.nlm.nih.gov/pubmed/17490954
- https://www.ncbi.nlm.nih.gov/pubmed/21990002
- https://www.ncbi.nlm.nih.gov/pubmed/24520882
- http://onlinelibrary.wiley.com/doi/10.1038/oby.2005.162/full
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2129145/
- http://jama.jamanetwork.com/article.aspx?articleid=1774038
Source: https://www.healthline.com/nutrition/12-weight-loss-pills-reviewed#section14