Figure 2.

Conditions required to assess the existence of diurnal/circadian rhythms in energy expenditure. The top section of the figure presents components of total energy expenditure and the methodologies and conditions required for assessment of energy expenditure (specifically RMR). To accurately assess TEF, certain factors such as macronutrient composition of meal need to be considered. The bottom section lists study protocols used to determine circadian and diurnal rhythms. Diurnal rhythmicity can be determined using a calorimetry approach (typically IC) and time of day protocols. Circadian rhythmicity requires a forced desynchrony approach with a calorimetry technique (typically IC).