Do eating and exercise impact DEXA results?
Overview
- What did they test? In this study, researchers tested the impact of exercise and modifying energy intake on resting metabolic rate and DEXA scan results in male and female endurance-trained athletes. Participants completed 5 experimental conditions and had their resting metabolic rate tested and received DEXA scans the next day. The experimental phases included: an energy intake designed to produce weight gain (GEI), a high energy intake rest day (HEI + Rest), a low energy intake rest day (LEI + Rest), a high energy intake exercise day (HEI + Ex), and a low energy intake exercise day (LEI + Ex).
- What did they find? There were no effects of exercise or modifying calorie intake on resting metabolic rate. However, the lower energy intake conditions led to reductions in total mass, fat-free mass, and lean body mass compared to the higher energy intake conditions regardless of previous day exercise.
- What does it mean for you? The results of this study suggest that diet and exercise performed on the day before testing do not affect resting metabolic rate, but do affect measures of lean body mass and fat-free mass as measured by DEXA. To increase the accuracy of DEXA measurements, it may be necessary to control energy intake the day before testing.
What’s the problem?
Accurate assessment of resting metabolic rate and body composition are important for determining baseline dietary needs, understanding body composition changes, and more. Currently, procedures for testing resting metabolic rate recommend fasting for at least 7 hours prior to testing but do not control for exercise 1 and procedures for DEXA testing are generally not standardized 2. Lack of standardization of energy intake and exercise in the 24 hours leading up to testing may lead to inaccurate assessment of resting metabolic rate and energy needs as well as misleading estimates of body composition and body composition change.
Purpose
The role of prior day exercise and energy intake on resting metabolic rate and DEXA body composition measures are currently not well understood. Therefore, the purpose of this study is to determine if reduced energy intake, exercise, or the combination of the two impact resting metabolic rate or body composition on the following day.
