Submitted to: The American Journal of Clinical Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/17/1997
Publication Date: N/A
Interpretive Summary: In order for adults to maintain body weight, and therefore good health, the energy contained in the food they eat must be the same as the energy they expend. The energy people expend depends on their size, age, physical activity and environment and is called energy requirement. Traditionally energy requirement is determined by asking people to write down what they eat and then analyzing this food record for energy content. Past research suggest that food records underestimate energy requirement. When 24 adult men and women were fed just enough food to maintain body weight, the energy they consumed was 21% more than what they reported with food records. When we used a stable isotope technique called doubly labeled water, their energy expenditure was 24% more than what they reported with food records. Finally, when we placed these people in a metabolic chamber called a room calorimeter their energy expenditure was 9% more than what they reported with food records. These comparisons demonstrate that the traditional method of using food records to establish energy requirement is inadequate. The results of these comparisons will aid researchers in nutrition, choosing the appropriate strategy when designing studies to investigate energy metabolism in humans. These comparisons will also help researchers interpret results of energy metabolism studies.
Technical Abstract: Energy intake (EI) determined by self reported dietary intake records was compared to EI determined by EI balance and energy expenditure (EE) determined by doubly labeled water and calorimetry in 24 (14 female and 10 male) adult subjects. Energy requirement was estimated using all four methods in each subject. EI measured by self reported diet records was 21% %less than EI measured by EI balance, 24% less than EE measured by doubly labeled water, and 9% less than EE measured by room calorimetry. EE measured by calorimetry was 17% less than EE measured by doubly labeled water. While mean EI and EE measurements were significantly lower in females compared to male subjects the mean difference between measurement methods were not. Direct comparison of these methods indicate self reported diet records and calorimetry underestimate energy requirement. While EI balance accurately estimates energy requirement, EE measured by doubly labeled water is a more direct approach. Multiple regression analysis relating EI balance and EE doubly labeled water to subject sex, body weight and EI intake balance suggest a linear relationship of these variables and energy requirement.