People often say that ‘diets don’t work’. Actually, it’s true – they don’t. The science supports what we have all experienced: you might lose weight for a few weeks or months, but it doesn’t last.
We’ve spent time looking at the evidence on long term effectiveness of diets. Here is a brief summary of the two key reviews of the evidence in recent years.
The largest study ever undertaken on the effectiveness of calorie controlled diets was published in 2007 by a team at UCLA.
This study concludes: “In sum, the potential benefits of dieting on long-term weight outcomes are minimal….and the potential harms of weight cycling, although not definitively demonstrated, are a clear source of concern.“
The authors also note that between one third and two thirds of dieters regain more weight than they lost, suggesting that the diets may be counterproductive in many cases.
A second important study at George Washington University (1999) reaches similar conclusions. The diets studied led people to lose weight, on average approximately 10kg, while the diets lasted. But once the diet was finished the figures are dramatic.
After 2 years 95% of dieters had regained the weight
After 3-5 years there was “almost complete relapse”
So as you probably already knew, diets might work to lose some weight for a few weeks, but they don’t work in the long term.