Research

Energy balance

Commercial weight loss programs (Atkins, Weight Watchers, Slim-Fast, Rosemary Conley) produce clinically significant weight and fat loss over six months, with no statistically significant difference in final efficacy between the four diets.

Choose a commercial weight loss program that you can realistically adhere to for at least six months. Expect to lose approximately 5-8 kg (11-18 lbs) and 4-5 kg of fat if you stick with it. Do not expect one specific brand (like Atkins or Weight Watchers) to be inherently superior to others in the long run; success depends on your ability to follow the specific rules of the chosen program consistently.

GoodSupportsHIGH confidence
All diets resulted in significant loss of body fat and weight over six months. Groups did not differ significantly but loss of body fat and weight was greater in all groups compared with the control group.
Helen Truby et al. · BMJ · 2006

Why this rating

Randomized controlled trial with a large sample size (N=300) and intention-to-treat analysis, though unblinded.

Source

Randomised controlled trial of four commercial weight loss programmes in the UK: initial findings from the BBC “diet trials”

Helen Truby et al. · BMJ · 2006

DOI 10.1136/bmj.38833.411204.80

rct · n=293Cited 288×
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DOI resolved against Crossref · corpus check 2026-06-10

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