Calories Count in Weight Loss - The Diet Composition Comparison Study


When I saw the headlines and heard the news reports about a new study that concluded the diet doesn’t matter as long as the calories are low, I had mixed thoughts. I was pleased that it was published in a Journal I subscribe to (and thus, not be limited to press releases), wondered if it was as definitive as it sounded on TV and radio, and reflected on how I learned calories were the key as a teenager who was overweight and lost it by eating less and moving more. And since I’ve always been in the calorie camp, I was curious if this study would hold up to those who make money by contending the problem lies with a calorie source rather than the calorie itself. Before we answer that question, here is what we do know:
1. When researchers can precisely control energy intake and output in the laboratory weight loss parallels energy deficit rather than the energy source.
2. In the real world of ‘free feeding,’ very few measure, monitor
and accurately track what they eat..

 3. In that same world, most people with excess weight tend to underestimate activity.
4. Whenever people pay attention to energy intake and output (a common occurrence when a new diet begins) weight loss happens.
5. Diets stop working because once the weight begins to come off, the dieter’s attention to detail wanes.
6. There are many ways for the masses to lose weight but only a few for the individual.      
7. If calories are not counted, the importance of their source rises because different sources and different ratios satiate different people differently.
8. A high percentage (of the low percentage) of people who don’t regain weight doesn’t stop monitoring their food choices and physical output.  A low percentage of these people keep the weight off by restricting on a single macronutrient.



The Study



811 volunteers were divided into 4 dietary groups and followed for 2 years. Intervention consisted of 18 group meetings in the first 6 months, 36 meetings in next 18 months an12 individual meetings over 24 months.  There were also questionnaires and diet diaries.

The groups were as follows:

         Group                                 Target breakdown              Actual breakdown

(C-P-F)                             (C-P-F)

Low fat, high carb                       65-15-20                          57-17-26

Low fat, high protein                   55-25-20                          53-21-26

High fat, moderate protein           45-15-40                         49-18-34

High fat, high protein, low carb    35-25-40                         43-34-23

The greatest weight loss occurred in the first 6 months in all groups.  All groups lost between 12-13 pounds.  At two years those that completed the study still weight 7-9 pounds less. The researchers concluded “Reduced-calorie diets result in clinically meaningful weight loss regardless of which macronutrients they emphasize.”  For many years I have agreed with this statement. Those who don’t will point out the obvious problems with this study— only one of the 4 groups met the macronutrient target despite extensive intervention.  The fact is they are correct.  For example, the comparison of a 65% carb vs. 35% carb diet was only 57% vs. 43%.  Low care advocates will say the low carg group didn’t have a low carb diet while high carb supporters will say the high carb group didn’t have a high carb diet.  This means that even though the studies author feel the issue is resolved, the paper will do little to change the minds of those who believe calories are secondary to a macronutrient imbalance.





Sacks, F.M., Bray, G.A., Carey, V.J. et al Comparison of Weight-loss Diets with Different Compositions of Fat, Protein, and Carbohydrates,

NEJM 2009;360:859-73.