The Cooper Institute

Founded in 1970 by the "Father of Aerobics"
Kenneth H. Cooper MD, MPH


Macronutrients matter... but it's calories that count

Posted in
Eat better

Thursday, Mar 05, 2009


The debate about what type of diet is most effective for weight loss seems never ending. Yesterday you were told to eat low fat and today you're told to cut out the carbohydrates. A new study now says that while macronutrients (fat, carbohydrate, protein) are important to consider for overall health, it's calories that really count for weight loss.

Reported in The New England Journal of Medicine, researchers assigned 811 overweight/obese adults to one of four reduced-calorie diets:

  • Low-fat, average protein (high carbohydrate) 
  • Low-fat, high protein
  • High-fat, average protein
  • High-fat, high-protein (low carbohydrate)
Study subjects were asked to record their food intake in a dairy or online tool, do moderate-intensity physical activity for at least 90 minutes per week, and attend group and individual counseling sessions every (or every other) month.

Results showed:

  • On average, participants lost 13 pounds at six months and maintained 9 pounds at two years
  • The macronutrient composition (amounts of fat, protein, and carbohydrates) of the diet did not predict amount of weight lost
  • Satiety, hunger, satisfaction with diet, and attendance at group sessions were similar for all diets
  • All diets improved risk factors (triglycerides, LDL-cholesterol, blood pressure, HDL-cholesterol, and metabolic syndrome) for heart disease
What's great about these results is that they support the notions that 1) calorie intake is key (and that's what SU&E's all about!) and 2) people can choose whichever reduced-calorie eating plan they think they will be most likely to stick with. For people who do a lot of "mindless eating" of carbohydrates (e.g., eating chips while on the computer or watching TV), they may benefit from a higher fat and protein diet that isn't conducive to snacking. On the other hand, someone who eats out frequently may benefit from a low fat diet that encourages them to choose plain chicken and fish instead of fried or high fat meats.

This flexibility to choose an approach that fits into someone's lifestyle is key to long-term change and weight loss.

What are your thoughts? 

Sacks, F.M. (2009).Comparison of weight-loss diets with different compositions of fat, protein, and carbohydrates. The New England Journal of Medicine. 360(9), 859-873.