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. -
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.)
