On February 26th a large, well designed trial comparing different weight loss diets was published in the New England Journal of Medicine. It was a good behavioral intervention over two years. They compared high and low protein, high and low fat, and different amounts of carbohydrates. The result: no difference in weight loss between any of the diets. Overall, the participants lost 6.5-9 pounds at the end of 2 years. This is a mild, but significant reduction.
We have now had a bunch of trials that show that many different diets "work", but only modestly. If we try and take these interventions into the clinical (i.e. non-research) world, we will likely have even less success.
So what do we take out of this? The editorial by Martijn Katan (linked to below) says it best:
"We do not need another diet trial; we need a change of paradigm."
He goes on to talk about how behavior change is hard, and we will only be effective if we work at a community level:
"Like cholera, obesity may be a problem that cannot be solved by individual persons but that requires community action. ...the apparent success of such community interventions suggests that we may need a new approach to preventing and to treating obesity and that it must be a total-environment approach that involves and activates entire neighborhoods and communities."
I have been advocating for this for some time. Obesity treatment (via dieting) is not the answer to this large public health problem. Obesity prevention through large scale public health research and interventions is the answer. Let's start taking responsibility for our laws, policies, and community designs that contribute to obesity. Let's all work together to make our communities healthy places for our children, spouses, friends, and parents to live in.
NEJM -- Weight-Loss Diets for the Prevention and Treatment of Obesity