Summary
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Do weight loss pills work?
There isn't overwhelming evidence that any dietary supplement enables significant, long-term weight loss. However, many small studies — typically funded by supplement companies -- suggest short-term weight loss, slimming (reducing fat but not overall weight), and/or appetite reduction (see What It Does for a summary of the evidence).
In this Review, CL focused on stimulant blends (which are some of the most popular weight loss supplements and contain caffeine and/or synephrine), as well as supplements with 7-keto DHEA or forskolin (from Coleus forskohlii). CL has separately reviewed many other types of supplements used for weight loss — see the list in What It Is.
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What did CL's tests of weight loss supplements find?
Laboratory tests and analyses by ConsumerLab revealed potentially dangerous amounts of caffeine in three products and a potentially dangerous amount of synephrine in another — twice the amount expected from its label. In addition, one Forskohlii supplement contained less than 5% of its expected forskolin. All of the 7-keto DHEA supplements contained their claimed amounts.
Across products, the dose of caffeine ranged from 51.6 mg to 270 mg per serving in stimulant blends, 7-keto DHEA ranged from 25 mg to 100 mg, and forskolin ranged from just 1.9 mg to 50 mg. The cost to obtain 100 mg of 7-keto DHEA ranged from 15 cents to $3.00 and the cost for 25 mg of forskolin ranged from 33 cents to $1.40 -- showing huge opportunity for savings when buying these products. For details, see What CL Found.
Top Picks for 7-Keto DHEA, forskolin, and stimulant blends —
Among products Approved in testing, ConsumerLab selected a Top Pick for 7-Keto DHEA and a Top Pick for Forskolin, with each providing the clinically tested dosage at relatively low cost. A Top Pick Stimulant Blend was also chosen that provided a safe level of caffeine.How much should I take and when?
Dosage for 7-Keto DHEA is typically 100 mg twice daily and for Forskohlii it is 25 mg of forskolin (from 250 mg of extract standardized to 10% forskolin) twice daily. For caffeine, there isn't sufficient research to suggest a dose effective for weight loss. See the ConsumerTips™ section for more about dosage and forms.Safety and side effects of weight loss supplements:
Stimulants and forskolin may affect blood pressure and heart rate and interact with medications. 7-keto DHEA may affect thyroid levels. (For details, see Concerns and Cautions.)
Products tested in 2019
+— 15 sources
In addition the results of its expert testing, ConsumerLab uses only high-quality, evidence based, information sources. These sources include peer-reviewed studies and information from agencies such as the FDA and USDA, and the National Academy of Medicine. On evolving topics, studies from pre-print journals may be sourced. All of our content is reviewed by medical doctors and doctoral-level experts in pharmacology, toxicology, and chemistry. We continually update and medically review our information to keep our content trustworthy, accurate, and reliable. The following sources are referenced in this article:
- Godard, Obes Res, 2005
- Gonzalez-Sanchez, J Int Med Res 2006
- Hansen, Tox and Applied Pharm 2012
- Henderson, J Int Soc Sports Nutr 2005
- Kiethly, Alt Ther 2005
- Kuriyan, Appetite 2008
- Morimoto, Life Sci 2005
- Onakpoya, Br J Nutr 2011
- Park, Planta Med 2010
- Kaiman, Cur Ther Res 2000
- Zenk J Nutr Biochem 2007
- Cohen, Clin Toxicol 2021
- Cohen, Drug Test Analysis 2015
- Davidson, Clin Invest Med 2000
- Foster, Clin Pharm & Ther 2013
You must
be a member to get the full test results for weight loss supplements along with ConsumerLab.com recommendations, comments, and quality ratings. You will get results for thirteen supplements selected by ConsumerLab.com for testing and for one other that passed voluntary Quality Certification Testing.
In this comprehensive review, you'll discover:
Which weight loss supplements failed testing and which passed
- ConsumerLab's Top Picks among products
- Direct comparisons, reviews, and quality ratings of weight loss supplements
- The pros, cons, and weight loss evidence for bitter orange, calcium, caffeine, Garcinia cambogia, stimulant herbs, chitosan, chromium, diuretics, ephedra, forskolin, green tea, hoodia, L-carnitine, pyruvate, raspberry ketone, 7-keto DHEA, stimulant laxatives like senna, and vitamin C
- Dosage for 7-keto DHEA and forskolin
- Concerns, cautions, and drug interactions for caffeine and many ingredients common in weight loss supplements
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