We have long known that people who work the night shift or rotate shifts find it easier to gain weight and harder to lose. Though we have been able to observe these differences, until now we did not know why this happened.
A recent research study (Human Resting Energy Expenditure Varies with Circadian Phase ) showed that the number of calories we use at rest is dependent on the time of day. We use 10% more calories in the late afternoon than in the middle of the night.
Calories at rest are those calories we burn just to keep the body functioning – regulating temperature, breathing, allowing the heart to beat and your organs to function – it is a big job and goes on 24 hours a day. The natural body rhythm suggests that we will be sleeping in the middle of the night and not need as many calories, as opposed to being up and moving midday. This research suggests that even if we are up and moving in the middle of the night, our body is not using as many calories as it could which might result in weight gain.
