Everybody knows somebody who knows the best way to lose weight. If you miss the latest diet fad discussed on a morning talk show, you can be sure the topic will come up during a coffee break, waiting to pick up your kids at school or while having your hair cut. And the kookier the diet, the more popular it will probably be. After all, it is more fun to eat like a skinny Frenchwoman, pray your way into weight loss or eliminate all foods except those grown in an organic compost heat than simply decrease portion size, watch out for hidden fat, and count calories.
Unfortunately, for those who hope that maybe the latest novelty diet will finally be the one to get them to lose weight, there is bad news. According to an extremely careful and rigorous study published at the end of February in the New England Journal of Medicine, any diet that makes the dieter eat fewer calories will work.
The scientists assigned over 800 obese adults to one of four different diet types. They were low fat, average protein; low fat, high protein; high fat, average protein; and high fat, high protein. Thus two diets were low fat and two were high fat; two were average protein and two were high protein. Similar foods were used for each diet, although the type of diet they were on determined the amounts that the volunteers ate. For example, those on a high protein, high fat diet might be allowed to fry chicken in a lot of oil and were restricted to a very small amount of rice whereas those on a low fat, average protein diet might be using less oil and eating a smaller portion of chicken and a larger amount of rice.
The study lasted two years. All the participants participated in group as well as individual counseling sessions. They had to keep food diaries and were encouraged to exercise 90 minutes per week.
Because this was a study and not a random group of people trying to lose weight, the participants were excluded if, for example, they were on medications such as antidepressants that could cause weight gain, or were not really committed to losing weight. However, the study took place over a long enough period of time so that the normal events that can disrupt a diet such as overwork, family problems, financial worries, social disappointments (breaking up with a boy or girlfriend for instance) and general stress could and probably did occur.
Did the type of diet affect how much weight was lost? No. After two years, weight loss was the same for people on high or average protein diets, the same for those on high fat (low carbohydrate) and low fat (high carbohydrate) diets. And even though the participants were given an enormous amount of support for two years and committed themselves to losing weight, most of the weight loss occurred in the first six months. Indeed, after the first year was over these dieters slowly regained their weight.
People who showed up regularly at the group sessions were more likely to lose weight consistently but that is not surprising. Dieting is lonely and often disappointing if weight is not being lost quickly enough. Group meetings really help dieters share their problems and successes and learn strategies for avoiding temptations.
The authors admit that as time went by, the dieters assigned to a particular combination of protein, fat and carbohydrate may not have followed the diet guidelines too strictly. They said that those people who were supposed to eat very little carbohydrate ate much more than they were allowed and presumably people on a low fat diet may have had some French fries and chocolate along the way. And all of them ate more than they were allowed after the first year. Otherwise they would have continued to lose weight, not slowly regain it.
Because this was a study, the researchers had to treat all the subjects the same. Even though support was given to the subjects so they understood how to stay on the diet and deal with situations that might be obstacles (such as catered meals or celebrations), the researchers could not deal with emotional issues that might have affected how individuals dieters adhered to the program. So it is not surprising that after the six months of novelty and support began to wear off, very little additional weight was lost. The study report doesn’t tell us what was being eaten when weight was regained. Was there more alcohol consumption, more cookies or fried chicken eaten?
What we learn from this study is that eating fewer calories than our bodies need will shed pounds. And it doesn’t matter if the calories are fewer because we are eating egg yolks and mayonnaise or brown rice and cooked carrots as long as the calories are controlled.
What we still don’t know is the best strategy to make our minds and our bodies switch to a permanent change in lifestyle so the weight lost will stay away.