Figure 2.

Profiles of circulating glucose and ketone levels over 48 hours in individuals with a typical American eating pattern or two different IF eating patterns. (a) In individuals who consume three meals plus snacks every day the metabolic switch is never ‘flipped’ and their ketone levels remain very low, and the area under the curve for glucose levels is high compared to individuals on an IF eating pattern. (b) In this example, the person fasted completely on the first day and then at three separate meals on the subsequent day. On the fasting day ketones are progressively elevated and glucose levels remain low, whereas on the eating day ketones remain low and glucose levels are elevated during and for several hours following meal consumption. (c) In this example the person consumes all of their food within a 6-hour time window every day. Thus, the metabolic switch is flipped on following 12 hours of fasting and remains on for approximately six hours each day, until food is consumed after approximately 18 hours of fasting. Modified from Mattson et al 2016.(9)