It’s Calories In vs. Calories Out

You know as well as we do that there's a lot of controversy about which diet is best for long-term weight loss. High fat? Low fat? No carbs? Some carbs? Even though there have been studies done on all sorts of diets, the results are contradictory at best (and the research not very well designed, at worst). Often these studies are done for short periods of time (six months or less) or don't include a good mix of men and women or just don't have many participants, period.

Researchers at Harvard University in Boston, Massachusetts partnered with researchers at Louisiana State University in Baton Rouge, Louisiana to create a study (N Engl J Med 2009; 360(9):859-73) that they hoped would overcome all of those barriers to quality research – and maybe even answer the question of what combination of protein, fat and carbohydrates would be best for long term weight loss.

They began by recruiting 645 overweight men and women to participate in a two-year program for weight loss. Each person was then randomly assigned to one of four diets:

• Low-fat, average-protein (20% fat, 15% protein, 65% carbohydrates)
• Low-fat, high-protein (20% fat, 25% protein, 55% carbohydrates)
• High-fat, average-protein (40% fat, 15% protein, 45% carbohydrates)
• High-fat, high-protein (40% fat, 25% protein, 35% carbohydrates)

All of the diets were healthy diets, in that they included less than 8% of calories from saturated fat and at least 20 grams of fiber per day. They were also low in dietary cholesterol, and the participants were taught to choose carbohydrates with a low glycemic index, regardless of how many carbs they were to eat.

Each person exercised moderately for about 90 minutes per week and participated in group and individual support sessions for the duration of the study. They received daily, individually customized meal plans in two-week blocks that aimed for a 750 calorie deficit in their daily caloric intake. They also tracked their food intake with an online food and exercise journal.

The researchers tracked the participants' weight loss regularly for the two years. They found, simply, that in the first six months all of the subjects lost about the same amount of weight, regardless of which dietary combination they were assigned to. They also regained about the same amount of weight after the first year of the diets. All told, however, about one-third of all who participated lost at least 5% of their body weight and kept it off throughout the study.

What this means for you

It seems clear that in order to lose weight, it really doesn't matter what you eat as long as you follow a healthy diet and reduce the number of calories you take in each day. So why not enjoy what you eat and lose weight? Med Diet Score can help you do just that.

First posted: April 8, 2009