How we distribute our food throughout the day can impact our health. Athletes often have workouts in the morning and fail to properly refuel afterwards, often waiting until the evening to have a large meal. As a result, most of the day they are in a calorie deficit. This is called “within day energy deficiency.” While calorie intake may be sufficient over a 24-hour period, many hours throughout the day are spent in a calorie deficit. Read on for why you should consider when you’re eating.
Within-day energy deficiency is associated with metabolic disturbances. A study compared the energy intake and number of hours spent in a calorie deficit in female endurance athletes with menstrual dysfunction (i.e. missing or irregular periods) or normal menstrual function. They found that 24-hour calorie balance was no different between groups but those with menstrual dysfunction spent more time in a calorie deficit. This is an important finding because missing or irregular periods could be a sign that not enough calories are being consumed. However, this highlights that it just isn’t about getting enough calories over 24-hours, but also how they’re distributed throughout the day.
A similar study was done in male endurance athletes. They grouped these male athletes as either having a normal resting metabolic rate or a suppressed resting metabolic rate. Having a suppressed resting metabolic rate is comparable to a female not having a period, signalling that the body is conserving energy because not enough calories are being consumed. Similar to the study in female endurance athletes, while the two groups had similar 24-hour calorie balance, those with a suppressed resting metabolic rate spent much more time throughout the day in a calorie deficit.
The suppressed resting metabolic rate could explain the results of the final study. This study compared energy intake among elite level gymnasts and runners and found that there was a negative correlation between the time spent in a negative calorie deficit and body fat levels. This means that more time spent in a calorie deficit was associated with increased body fat levels. This could be the result of a suppressed resting metabolic rate that would reduce the number of calories the body needs.
All these studies provide good evidence that we should pay close to attention to how we’re distributing our calories throughout the day. It’s not just what you eat, but when you eat that is important for health.