Lipid, protein and carbohydrate intake in relation to body mass index.

OBJECTIVE

To examine whether the same amount of energy intake has different consequences on body mass index (BMI), depending on the source of energy from specific macronutrients.

DESIGN

Cross-sectional study, in the context of the European Prospective Investigation into Cancer and nutrition (EPIC).

SETTING

Communities all over Greece.

SUBJECTS

A total of 27 862 apparently healthy volunteers, men and women, ages 25-82 y.

INTERVENTIONS

None.

METHODS

Dietary information was collected through an interviewer-administered semi-quantitative food frequency questionnaire. In the context of a cross-sectional analysis, we calculated changes of BMI per increments of energy intake from protein, carbohydrates, saturated, polyunsaturated and monounsaturated lipids and ethanol, controlling for mutual confounding and other confounders, among all participants, and after exclusion of under-reporters and/or those on a diet.

RESULTS

Protein intake was positively associated with BMI. The association was evident when nutrients were not mutually adjusted for and increased after mutual adjustment among nutrients (beta=0.80 kg/m(2) per 418.4 kJ or 100 kcal increment, 95% confidence interval 0.55-1.06 for men, and beta=1.59, 95% CI 1.30-1.88 for women), as well as after exclusion of under-reporters and/or those on a diet. The effects of other macronutrients were less substantial or consistent.

CONCLUSIONS

There is evidence indicating that protein intake is conducive to obesity. Moreover, our data suggest that neither saturated or monounsaturated lipids nor carbohydrates are likely to play a major role in increasing BMI over and beyond that indicated by their energy content.