You will not lose 1lb every time you create a deficit of 3,500 calories

The myth “To lose one pound of fat you need to create a deficit of 3,500 calories” is actually worse than a myth – it is one of the cruellest lies we have told desperate dieters. We have known since Benedict’s study in 1917 (Ref 3) that we don’t lose anywhere near this much weight and we regain any weight lost and more. The 1945 Keys Minnesota Starvation experiment (a 1,600 calorie a day diet was called starvation) was the most comprehensively documented ever. (Ref 4) He also showed that his 36 subjects, rigorously studied in confinement over a one year period, did not lose anywhere near what the 3,500 formula promises. They all regained all the weight that they did lose – plus about ten percent.

Weight Watchers beautifully proved that this formula does not hold in a study published in July 2010: On July 12 2010, under the headline “Weight Watchers does work, say scientists”, Sarah Boseley, health editor for The Guardian wrote a wonderful endorsement for Weight Watchers following a study done by the Medical Research Council (MRC), funded by Weight Watchers (Ref 5). The original presentation of results from the MRC revealed that 772 people were studied: 395 people were simply given weight loss advice from their doctor (the GP group) and 377 were funded to attend Weight Watchers (419 of the 772 completed their respective programme). (Ref 6)

The study was a year in length and the likely deficit was at least 1,000 calories per day (a typical Weight Watchers allowance is 18-20 points, which approximates to 900-1,000 calories vs. an average 2,000 calorie requirement for a woman). The article reported that the GP group lost an average of six pounds (we know from the Marion Franz 2007 (Ref 7) study that ‘advice alone’ people did well to lose anything) and the Weight Watchers group lost an average of 11 pounds. The Weight Watchers group should have lost 104 pounds in fat alone (2lbs a week for 52 weeks).

This study provided irrefutable proof that the calorie theory is wrong, which should have been front page news in itself, but this was not the story of the article. The story was “you’ll lose twice as much weight with Weight Watchers.” The headline should more accurately have been “Weight Watchers works better than just going to the GP, says study funded by Weight Watchers; but you will be lucky to lose one tenth of your lowest expectation.” Not as catchy, but far more honest.

p.s. if you want to see how two people can eat the same number of calories and one gets fats and sick while the other gets slim and healthy – here’s how.


Ref 3: Francis G. Benedict, Human Vitality and efficiency under prolonged restricted diet, (study 1917, published 1919). (See reference 14 The Obesity Epidemic)

Ref 4: Ancel Keys, The Biology of Human Starvation, (study 1944-45, report 1950). (See reference 15 The Obesity Epidemic)

Ref 5: (See reference 104 The Obesity Epidemic)

Ref 6: (See reference 105 The Obesity Epidemic)

Ref 7: Marion J. Franz, Jeffrey J. VanWormer, A. Lauren Crain, Jackie L. Boucher, Trina Histon, William Caplan, Jill Bowman, Nicolas Pronk. “Weight Loss Outcomes: A Systematic Review and Meta-Analysis of Weight Loss Clinical Trials with a Minimum 1-Year Follow-Up”, Journal of the American Dietetic Association, (2007). (See reference 99 The Obesity Epidemic)