Abstract
Effects of protein versus mixed macronutrient supplementation on total energy intake (TEI) and protein intake during an ad libitum diet were examined. Trained males undertook two, 2-week dietary interventions which were randomised, double blinded and separated by two weeks. These were high protein supplementation (HP: 1034.5 kJ energy, 29.6 g protein, 8.7 g fat and 12.3 g CHO) and standard meal supplementation (SM: 1039 kJ energy, 9.9 g protein, 9.5 g fat, and 29.4 g CHO), consumed daily, following a week of baseline measures. Eighteen participants finished both interventions and one only completed HP. TEI (mean±SD) was not different between baseline (11148±3347 kJ) and HP (10705±3143 kJ) nor between baseline and SM (12381±3877 kJ), however, TEI was greater with SM than HP (923±4015 kJ p=0.043). Protein intake (%TEI) was greater with HP (22.4 ±6.2 %) than baseline (19.4±5.4 %) (p=0.008) but not SM (20.0±5.0 %). No differences in absolute daily protein intake were found. Absolute CHO intake was greater with SM than HP (52.0±89.5 g, p=0.006). No differences in fat intake were found. Body mass did not change between baseline (82.7±11.2 kg) and either HP (83.1±11.7 kg) or SM (82.9±11.0 kg). Protein supplementation increases the relative proportion of protein in the diet, but doesn't increase the absolute amount of total protein or energy consumed. Thus some compensation by a reduction in other foods occurs. This is in contrast to a mixed nutrient supplement, which does not alter the proportion of protein consumed but does increase TEI.