Physical activity is defined as any bodily movement produced by skeletal muscles that results in energy expenditure. The benefits of physical activity for health maintenance have been well documented, especially in the prevention and management of chronic diseases. Therefore, accurate measurement of physical activity and energy expenditure is essential both for epidemiological studies and in the clinical context. Given the large number of available methods, it is important to have an understanding of each, especially when one needs to choose a technique to use. The purpose of this review was to discuss the components of total energy expenditure and present advantage and limitations of different methods of physical activity and energy expenditure assessment.

During the management of critical illness, optimal nutritional support is an important key for achieving positive clinical outcomes. Compared to healthy people, critically ill patients have higher energy expenditure, thereby their energy requirements and risk of malnutrition being increased. Assessing individual nutritional requirement is essential for a successful nutritional support, including the adequate energy supply. Methods to assess energy requirements include indirect calorimetry (IC) which is considered as a reference method, and the predictive equations which are commonly used due to the difficulty of using IC in certain conditions. In this study, a literature review was conducted on the energy metabolic changes in critically ill patients, and the implications for the estimation of energy requirements in this population. In addition, the issue of optimal caloric goal during nutrition support is discussed, as well as the accuracy of selected resting energy expenditure predictive equations, commonly used in critically ill patients.

Objectives: This study assessed the accuracy of the 24-hour diet recall method for estimating the energy intake of elderly men using the doubly labeled water as a reference method. Methods: Seventeen subjects (mean age 72.5 ± 3.9 years), who maintained the same body weight during the two weeks study period, were included in this study. Three 24hour diet recalls (two weekdays and one weekend) were obtained over a 14 day period to estimate the mean energy intake. The total energy expenditure was measured over the same 14 days using the doubly labeled water method. The total energy intake and total energy expenditure were compared by paired t-test. Results: The total energy intake from the 24-hour diet recalls method was 2536.7 ± 350.6 kcal/day, and the total energy expenditure from the doubly labeled water method was 2659.8 ± 306.8 kcal/day. The total energy intake was slightly under-reported by-123.2 ± 260.8 kcal/day (-4.4%). On the other hand, no significant difference was observed between the total energy intake and total energy expenditure of the subjects (p=0.069). The percentage of accurate predictions was 64.7%. The correlation between the total energy intake and total energy expenditure was statistically significant (r=0.697, p<0.005). Conclusions: The present study supports the use of the 24-hour diet recall method to estimate the mean energy intake in elderly men group. More studies are needed to assess the validity of 24-hour diet recall method in other population groups, including elderly women, adults and children.