Dietary Standardisation in a Nutrient plus Exercise Intervention: Derivation, Implementation, and Evaluation

Abstract

The objective was to devise and implement a dietary standardisation protocol for use in nutrient plus exercise intervention studies, and to report participant adherence to, and acceptability of same. The context was a nutrient plus exercise intervention study undertaken by resistance-trained men (18 to 35y). Participants’ habitual, seven-day, weighed dietary intake records informed the dietary standardisation protocol. Participants received a six-day meal plan that was prescribed relative to their body mass and provided 35 kcal∙kg-1∙d-1 comprising 2.0 g∙kg-1∙d-1 protein (including 0.33 g∙kg-1 of dietary protein supplement), 4.5 g∙kg-1∙d-1 carbohydrate, and 1.0 g∙kg-1∙d-1 fat. Apportioning of total protein intake was evenly distributed across six eating occasions (EOs), at three-hour intervals during waking hours. Median (25th-75th percentile) participant adherence to the prescribed meal plan was 100 (99-100)% for energy, carbohydrate and fat intakes, 100 (100–100)% for protein intake and frequency of EOs consumed, and 97 (93–100)% for distribution of EOs consumed. On study completion, 10 participants (45%) expressed that the standardised diet was easy to follow. Ten participants (45%) indicated activities of daily living as the primary challenge to adherence. The offered dietary standardisation (i.e. a protocol introduced 72 hours before the intervention study and a standardised diet) was effective in minimising the variability of dietary intake among participants undertaking a nutrient plus exercise intervention. The dietary standardisation resulted in high participant adherence and was well accepted.