Calories in, calories out. We’ve all heard this basic, fundamental calculation regarding weight loss and weight gain. To lose weight, we must expend more calories than we take in. Consume more than you need, and the result? The pounds go on. Turns out, lack of sleep may increase daily calorie consumption, and contribute to weight gain.
There is a tremendous amount of evidence that sleep plays an important role in weight management. Insufficient sleep is strongly linked to obesity and metabolic disorders, as well as to diabetes. But we’re still working to understand the underlying mechanisms by which sleep can influence weight.
A new study examined the effects of insufficient sleep on weight gain, and looked specifically at energy intake (calories in) and energy expenditure (calories out). Researchers investigated the effects of sleep on these two critical factors in weight management. What did they find? During periods of insufficient sleep, people increased their calorie consumption and as a result gained weight. What’s more, people who slept too little consumed more of their calories later in the day, which may further contribute to weight gain.
Researchers included 16 adults in a 14-15 day inpatient study. All volunteers were in good health, and at a healthy weight. Participants spent the roughly 2-week study period in a controlled environment, where researchers could manage and monitor their sleep and eating patterns. Researchers collected baseline health and weight measurements from all 16 volunteers during the study’s first 3 days. During this time participants were allowed to sleep to a maximum of 9 hours per night. Their eating was regulated during this 3-day period so they were only consuming what they needed to maintain their initial weight.
Next, researchers split participants into 2 groups. One group continued to be allowed to sleep for as much as 9 hours nightly. The other group was limited to 5 hours of sleep per night. They slept this way for 5 consecutive nights, in a sleep pattern designed to mimic a typical workweek. During this 5-day period, both groups were allowed the same unrestricted access to food. Participants were allowed to eat larger meals, and were given free access to snacks between meals. Snack foods included both low-calorie options like fresh fruit, and high-calorie, high-fat choices such as chips and ice cream. After 5 days, the groups switched sleep schedules, for another 5-day cycle. During both 5-day phases, researchers conducted measurements and analysis of participants’ sleep and their energy expenditure.
Their results shed light on the relationship of sleep to calorie consumption and output, and on some of the ways that sleep may contribute to weight gain. Researchers found:
These results strongly align with other recent research on the impact of poor sleep on weight. In particular, we’ve seen other studies suggest the restricted sleep may make it more difficult for people to choose healthful foods, and that lack of sleep may contribute to a shift in calorie consumption to later in the day, to the detriment of our waistlines.
The challenge of maintaining a healthy weight is a daily endeavor, made up of many small choices—what to eat? how much? when?—that over time have a powerful cumulative effect. A strongly routine of sufficient nightly sleep can aid in this endeavor, helping your body and mind work at its best, every day, for weight control and overall health.
Michael J. Breus, PhD
The Sleep Doctor™