Does a Lack of Sleep Lead to Increased Abdominal Fat?

We all know that sleep is important, or we should. But how important is it to your body composition goals?

We also know that resistance exercise and optimal nutrition are 2 of the foundational pillars to creating a muscular, lean physique. I’ve devoted my professional life to researching the best exercise and nutrition strategies to build muscle and while maintaining relatively lower body fat levels.

As a fitness professional I am consistently searching for other meaningful components (other than exercise and nutrition) to optimize one’s physique within a maintainable lifestyle, I am constantly confronted with the ‘lifestyle’ variable of SLEEP!

The third pillar to optimizing your physique, alongside resistance training and nutrition.

One of thing things that I’ve learned from the top physique coaches, is that they place a high importance on quality and quantity of sleep each night for their clients. As well as lowering stress levels as much as possible (allows for better sleep).

Over the past decade, there’s been a lot of sleep-related research conducted in relation to its health-related outcomes. We’ve been able to learn a lot about sleep due to this research.

One of the more pertinent and practical findings that has been reported is that in order to promote optimal health and well- being, adults should sleep about 7 hours each night. Sleeping less than 7 hours per night is associated with increased risk for obesity, diabetes, high blood pressure, coronary heart disease, stroke, frequent mental distress, and death.

Clearly, getting adequate sleep is important for overall health. Unfortunately, a lot of people do not get enough sleep. For example, habitual sleep deficiency (getting less than 7 hours per night) affects more than one-third of the adult population in the United States.

So how does inadequate sleep impact one’s physique? There is not a lot of experimental studies on sleep curtailment and body composition regulation. Of the few studies that do exist, the results are limited and conflicting. Does sleep deprivation cause an increase in body fat? The current research about this is unclear.

One of the reasons we don’t have definitive answers to this question is because there are major limitations of previous sleep studies. The main limitations of these studies include short duration of sleep manipulation and the use of non-ideal measures of body fat.

The study that reviewed was the first-ever study to assess the effects of sleep restriction on body fat distribution (specific areas of the body where body fat is stored). What they observed was fascinating—that experimentally reducing sleep affects where excess body fat is stored—in the abdominal region!

The participants of the study were 12 healthy, nonobese males and females between the ages of 19 and 39 who averaged about 7.5 hours of sleep per night. The participants lived in a research unit of 2 periods of 21 days at a time, for a total of 42 days in the facility.

During one of the periods the participants were given a normal sleeping window of 9 hours for 14 consecutive days. On the second period they were given only a 4-hour sleeping window for the 14 consecutive days. The other 7 days consisted of an acclimation phase of 4 days and a recovery phase of 3 days.

All sleep and intake were monitored and controlled by research the staff. In addition to being directly observed by the research staff during the sleep opportunities, the researchers also used a device (ambulatory polysomnography) to monitor sleep stages, arousals, total sleep time, and respiratory disturbances.

During both 21-day research periods, the subjects were studied in a sedentary setting with ad libitum food access. This means that there was no exercise component to the study and the subjects could have as much food as they wanted and as often as they wanted it.

One of the most fascinating findings of this study was that during the Sleep Restriction Condition (4-hour sleep window), the subjects ingested significantly more total calories as compared to when they were allowed to sleep for a normal amount of time. Not getting adequate sleep resulted in consuming approximately 300 more calories each day!

As a result, while both conditions gained body fat, the Sleep Restriction Condition saw a gain of a little over one pound more gain than the Normal Sleep Condition. This was a statistically significant difference in body weight change between the two sleep conditions.

Interestingly, there were no statistically significant differences between the two sleep conditions for total body fat or body fat %. Also, there were no significant differences in muscle mass between the two conditions, but this is not surprising since there was no effort to increase muscle mass and even if there was the duration of the trial was only 2 weeks (not enough time to detect meaningful changes in muscle mass).

Where things get interesting with this study is the abdominal fat measures. The total abdominal fat area increased significantly during the Restricted Sleep Condition but barely changed at all during the Normal Sleep Condition.

In the discussion section of the published research article, the authors summarized their results as follows: “Furthermore, in this first- ever study assessing the effects of sleep curtailment on body fat distribution, we report the novel observation that expansion in abdominal adipose tissue and especially visceral fat deposition occurred only in response to shortened sleep.”

Simply put, the results of this study indicate that restricting sleep (at least in the short term) results in depositing significant amounts of subcutaneous body fat (visible fat, this works against your efforts to have a lean physique) and visceral fat (organ fat, this works against your efforts to optimize your health).

Most clients know they need to be prioritizing sleep, but it's easily neglected. Especially in today’s world of go, go, go. We're all busy, trying to get this, that, and everything else done and then even sometimes when we have the sleep opportunity, we can struggle to fall asleep or stay asleep.

So, what are some things that you can do to improve your sleep quality and quantity?

• Sleep in a cool, dark room to encourage optimal sleep.
• Find ways to relax your mind before bed. This could include journaling, reading, meditating, praying or breath work.
• Heat exposure before bed (like sauna, hot bath, or hot shower) can help initiate sleep.
• Time sleep supplements 30-60 minutes before bed, so they have time to optimally kick in.
• Get plenty of light exposure early in the day, ideally in the form of outdoor sun viewing - even if it's cloudy!

And some things to avoid:

• Avoid bright light at night. Dim your lights or use lower wattage lamps as the nighttime approaches.
• Avoid screens late at night. This goes for your TV, computer, and phone screens.
• Avoid your phone... probably all together. I can confidently say that scrolling social media at night is simultaneously one of the hardest habits to break, but easily one of the worst practices for encouraging optimal sleep.
• Avoid eating too close to bed. This disrupts most clients' sleep in some capacity, especially a large meal. I do hypothesize that there is a total calorie component here too. As in, if someone is eating at maintenance or a surplus, they will be impacted more by a large meal, whereas a client deep in a deficit will be impacted less from the timing of their meal. Clients deep in a deficit will likely experience sleep disruptions, but for a different reason. Regardless, eating too close to bed generally should be limited.
• Adjust caffeine timing and/or amount if you are finding that your sleep is disrupted. Everyone metabolizes caffeine differently, so individual variability will be broad here. Pay attention to your biofeedback and adjust as necessary!

And once again CONSISTENCY is key! Developing a consistent sleep routine and schedule helps to regulate the bodies circadian rhythms. Allowing for optimal sleep hormone production. The more sporadic your sleep schedule is, the less your body can understand when it is supposed to be going to sleep. Of course, life happens and there will be variations in your schedule, whether that's with children's sleep schedules, an early flight, a late night out... no one is suggesting you must be a sleep robot (well, I'm sure there are some people but I'm certainly not!) but not having some sort of normalcy amongst a routine bedtime and wake time disrupts everything from body fat, muscle growth, hormone production, mood and cognitive functioning. Our bodies love consistency – whether that's with diet, or training, and our sleep!

Link to study:

https://pubmed.ncbi.nlm.nih.gov/35361348/#:~:text=Conclusions%3A%20Sleep%20restriction%20combined%20with,predisposes%20to%20abdominal%20visceral%20obesity.