If you've taken your dieting advice from pop diet book authors in recent years, you'd think that calories are not important or at least of secondary importance when it comes to battling the bulge. The largest dietary trial of its kind - published in the New England Journal of Medicine shows that calories matter - no matter how you split them.

More than 800 overweight adults in were assigned to one of four diets that reduced calories through different combinations of fat, carbohydrates and protein. Each plan cut about 750 calories from a participant's normal diet, but no one ate fewer than 1,200 calories a day.

While the diets were not named, the eating plans were all loosely based on the principles of popular diets like Atkins, which emphasizes low carbohydrates; Dean Ornish, which is low-fat; or the Mediterranean diet, with less animal protein. All participants also received group or individual counselling. The breakdown of calories was as follows:

Group I: 20% Fat, 15% Protein and 65% Carbohydrate
Group II: 20% Fat, 25% Protein and 55% Carbohydrate
Group III: 40% Fat, 15% Protein and 45% Carbohydrate
Group IV: 40% Fat, 25% Protein and 35% Carbohydrate

Here are the findings

* After two years, every diet group had lost -- and regained -- about the same amount of weight regardless of what diet had been assigned.
* Participants lost an average of 13 pounds at six months and had maintained about 9 pounds of weight loss and a two inch reduction in waist size after two years.
* While the average weight loss was modest, about 15 percent of dieters lost more than 10 percent of their weight by the end of the study.
* After about a year many returned to at least some of their usual eating habits.
* While health markers for cardiovascular disease and diabetes were similar, the highest carb group did not reduce fasting serum insulin levels
* All diets decreased triglycerides and blood pressure fairly evenly
* The lower fat diet reduced LDL cholesterol moreso than the high fat diet, while the highest fat, lowest carb diet raised HDL cholesterol moreso than the high carb, low fat diet.

While attendance at counselling sessions were linked with better weight loss, this was not true for every dieter.

According to lead researcher Dr. Frank Sacks:

The effect of any particular diet group is minuscule, but the effect of individual behavior is humongous. We had some people losing 50 pounds and some people gaining five pounds. That's what we don't have a clue about. I think in the future, researchers should focus less on the actual diet but on finding what is really the biggest governor of success in these individuals.


As the researchers pointed out, behavior seems to be central. Almost all long term studies on diet and weight loss seem to follow the same pattern regardless of the dietary intervention; a somewhat rapid weight loss in the first 6 months followed by a regain.

On a positive note, most people of this age group tend to gain on average 4-5 pounds in the same time frame of this study. Therefore, a 9 lb loss and a couple of inches over this span can definitely provide a health boost.

It seems we have to figure out how to make long term habit changes to steadily and significantly change health for the better.