The balance between weight gain and weight loss is mainly determined by what you eat, how much you eat and how much exercise you get. But another important factor is often neglected… New research conducted by Vanderbilt University, USA shows that it's not just how many calories you eat, but WHEN you eat them that will determine how well you burn those calories.
Your daily biological clock and sleep regulate how the food you eat is metabolized; so the choice of burning fats or carbohydrates changes depending on the time of day or night. Your body's circadian rhythm has programmed your body to burn fat when you sleep, so if you skip breakfast and then have a snack in the evening, you slow down the burning of the fat.
The researchers monitored the metabolism of middle-aged and elderly individuals in a room for two separate 56-hour sessions, using an experimental random crossover design. In each session, lunch and dinner were presented at the same times (12:30 and 5:45 p.m., respectively), but the timing of the third meal differed between the two halves of the study. For example, in one of the 56-hour periods, the additional daily meal was presented as breakfast (8:00), while in the other session, a nutritionally equivalent meal was presented to the same subjects as a late-night snack (22:00). . The duration of the nighttime fast was the same for both sessions.
While the two sessions did not differ in the amount or type of food eaten or in the subjects' activity levels, the daily timing of nutrient availability, coupled with clock/sleep control of metabolism, altered the switch in the subjects' fat/carbohydrate preference such that the late evening snack resulted in less fat burning compared to the breakfast session. The timing of meals during the day/night cycle therefore influences the extent to which ingested food is used versus stored.
This study has important implications for eating habits and suggests that daily fasting between dinner and breakfast optimizes weight management.
