Are you struggling to lose weight even though you are exercising and eating a healthy diet? Research now suggests that sleep quality may have a big role to play when it comes to getting rid of excess body fat.
Although studies have already found that sleep deprivation can make unhealthy foods more desirable and a high quality diet can improve sleep, newer research suggests that sleep has a big role to play when it comes to regulating our weight and levels of body fat.
A 2018 study published in the journal Sleep set out to examine the effect of sleep restriction on body weight, body composition, and metabolism. Researchers recruited healthy sleepers who were considered to be overweight or obese (defined by a Body Mass Index of 25-40). Participants were randomly assigned to a group that underwent calorie restriction for eight weeks or a group that underwent both calorie restriction and sleep restriction.
Calorie restriction to lose weight
For the calorie restriction portion of the study, participants consumed 95 percent of their resting metabolic rate (the number of calories your body needs over the course of one day when at rest). Calories were divided among:
- Breakfast (25 percent)
- Lunch (30 percent)
- Dinner (35 percent)
- Snack (10 percent)
In terms of nutrition:
- 50 percent of calories came from carbohydrate
- 30 percent came from fat
- 20 percent from protein
Lunch and dinner meals were provided to participants. Dietary guidelines were given to participants so they could prepare their own breakfast and snacks.
Participants were given three free days each week. For these free days, no calorie restriction was required — participants could consume what they liked (but were asked to record all food and drink they consumed).
The role of sleep
To test the influence of sleep quality, those in the sleep restriction group were told to restrict the amount of time they spend in bed by 90 minutes for five days each week, and to keep a regular sleep schedule. For the remaining two days, participants could sleep as they pleased.
Researchers measured the sleep duration of participants in this group using actigraphic monitors (medical-grade versions of consumer sleep trackers).
How calories and sleep affect weight loss
The study found that both groups has similar changes in body weight, with participants losing an average of around seven pounds over the eight weeks. However, the proportion of total mass lost as fat was significantly greater among those who did not experience sleep loss.
In other words, less sleep led to less body fat loss. Furthermore, since participants in the sleep restriction group were allowed to sleep as they liked for two days each week, these findings suggest that even catch-up sleep may not be enough to reverse this consequence of sleep deprivation.
Why does sleep deprivation make it harder to burn fat?
Unfortunately, we still don’t know for sure! The authors of this study pointed out that previous research has suggested that leptin (a hormone that suppresses food intake) and ghrelin (a hormone that stimulates the appetite) may be affected by sleep. Specifically, sleep deprivation appears to reduce leptin levels and increase ghrelin levels.
What we can take away from this study is that sleep appears to play a big role in how our body regulates weight. If we don’t get enough sleep (or get poor quality sleep) we may find it harder to lose body fat and we may be more likely to gain weight.
If you are struggling to lose weight, make sure you are giving sleep the same level of importance as exercise and diet.