FIGURE 1.

Categorization of popular diet practices. For CER (1), during which daily energy intake is reduced by up to 40%, but meal frequency and timing remain unchanged; IF (2), where 1 d or several days of fasting are interspersed with normal ad libitum eating patterns, such that total weekly energy intake is reduced, and meal frequency and timing remain unchanged on the days of food intake; or TRE (3), in which food is consumed ad libitum throughout a set time period, and energy intake may or may not be reduced. In TRE, the daily eating duration (i.e., the time between the first and last energy intake) is typically reduced from a 12–14-h/d “eating window” to ∼8-10 h/d. CER, chronic energy restriction; IF, intermittent fasting; TRE, time-restricted eating.