Menstrual-cycle patterns in energy and macronutrient intake.

For 14 subjects drawn from the Beltsville One-Year Dietary Intake Study, patterns of energy, protein, fat, carbohydrate, protein/1000 kcal, fat/1000 kcal, and carbohydrate/1000 kcal were examined across pre- and postmenstrual periods. Individual subjects contributed data for one to four menstrual periods. Energy, fat, and fat/1000 kcal intakes were significantly higher in the 10 premenstrual days than in the 10 postmenstrual days. After elimination of effects attributable to between-subject differences and to balance periods included in the Beltsville study, fitted sine curves explained 14% and 25% of the variance in energy and fat intakes, respectively, across 14 premenstrual and 14 postmenstrual days, and 20% of the variance in fat/1000 kcal. Independent patterns were identified in absolute and relative protein intake. No patterns were discerned for carbohydrate. Physiological or behavioral factors appear to influence both total food intake (energy intake) and food selection (macronutrients/1000 kcal) across the menstrual cycle.