Trends in energy and macronutrient intakes by weight status over four decades.

OBJECTIVE To examine whether the recent increasing prevalence of obesity was accompanied by variations in energy and macronutrient intakes by weight status. DESIGN Time series of cross-sectional surveys. SETTING National Health and Nutrition Examination Surveys (NHANES) in the USA. SUBJECTS Adult participants of NHANES I (1971-1974), II (1976-1980), III (1988-1994) and continuous (1999-2004). RESULTS Daily energy intake increased over time for men (9832 to 11 652 kJ, P < 0·01) and women (6418 to 8142 kJ, P < 0·01) in all BMI classes. Percentage of energy intake from carbohydrate increased over time (men: 42·7% to 48·0%, P < 0·01; women: 45·4% to 50·6%, P < 0·01), whereas percentage of energy intake from fat (men: 36·7% to 33·1%, P < 0·01; women: 36·1% to 33·8%, P < 0·01) and protein (men: 16·4% to 15·1%, P < 0·01; women: 16·9% to 14·7%, P < 0·01) decreased. With surveys combined, daily energy intake varied among BMI classes for women (underweight/normal weight: 7460 kJ; overweight: 6799 kJ; obese I: 7033 kJ; obese II/III: 7401 kJ; P < 0·01) but not men. Percentage of energy intake from carbohydrate decreased with increasing BMI class (men: 46·6% to 45·5%, P < 0·01; women: 49·0% to 48·6%, P < 0·01) whereas percentage of energy intake from fat (men: 34·3% to 36·5%, P < 0·01; women: 34·4% to 35·4%, P < 0·01) and protein (men: 15·3% to 16·5%, P < 0·01; women: 15·2% to 16·0%, P < 0·01) increased. Interactions of survey period and BMI class were not statistically significant. CONCLUSIONS Time trends in energy and macronutrient intakes were similar across BMI classes. Research examining how individuals respond differently to varying dietary compositions may provide greater insight about contributors to the rise in obesity.