Sleep and Weight Loss

Rest and relaxation are essential for health, well-being, and weight loss.

Whether you’re just starting your journey with phentermine, about to finish, or trying to maintain your weight after phentermine stopped working or treatment ended, it’s important to get plenty of sleep.

Sleep and Weight Loss Facts

  • 1 in 3 American adults don’t get enough sleep ( 1 )
  • Subjects report 24% more hunger and 45% more cravings for high-carbohydrate, salty “junk” foods when sleep-deprived ( 2 )
  • Young adults consume an average of 600 extra calories per day when sleep-deprived ( 3 )
  • People who sleep 5.5 hours/night lose more lean muscle mass when dieting than those who sleep 8.5 hours/night ( 4 )
  • Just 4 days of too little sleep significantly affects insulin sensitivity in adults ( 5 )

How Does Sleep Affect Weight Loss?

woman sleeping peacefully in her bed
For most of us, getting plenty of sleep and weight loss success go hand in hand

Weight loss relies not only on effective stress management during the day but also on quality sleep and recovery overnight.

Many people skimp on sleep to make more time for daytime activities, but a lack of sleep can wreak havoc not only on weight loss but also on overall health.

Sleep is important for weight loss because getting enough sleep:

1. Promotes Healthy Choices

Sleep deprivation dulls activity in the brain’s frontal lobe – the area responsible for logic, decision-making and impulse control – while increasing responsivity in the amygdala, the area that processes reward and emotion ( 3 ). The combination of decreased impulse control and increased reward makes harder to resist temptation, even if you know that the choice is not healthy.

Skimping on sleep also increases feelings of hunger and cravings for high-calorie foods. Research shows that sleep-deprived subjects report 24% more hunger and 45% more cravings for high-carbohydrate, salty “junk” foods ( 2 ). When left to eat what they want, participants consume an average of 600 extra calories while short on sleep ( 3 ).

2. Balances Hormones

Sleep deprivation increases ghrelin and decreases leptin. These changes make hunger cues stronger and decrease feelings of satiety, making you more likely to overeat.

Lack of sleep also increases the stress hormone, cortisol. The body perceives extended waking hours as form of stress, so cortisol production goes into overdrive to provide extra energy. Unfortunately, cortisol provides this additional energy by telling your body to store more visceral (abdominal) fat and break down lean muscle tissue.

In fact, a study from the University of Chicago found that dieters sleeping an average of 5.5 hours/night lost significantly more lean muscle mass than their counterparts who slept an average of 8.5 hours/night. This shift is problematic because losing lean muscle mass slows metabolism and makes it harder to lose or maintain weight, even with strict dieting ( 4 ).

3. Supports Healthy Metabolism

Sufficient sleep also promotes weight loss by supporting a healthy metabolism. Not only does nighttime rest supply much-needed energy to take on the day and exercise, it also prepares the body to burn more calories at rest.

In fact, studies have shown that after just four days of too little sleep (4.5 hours/night) significantly decreases subjects’ ability to use blood sugar (glucose) for energy ( 5 ). When your body can’t use the glucose in your bloodstream properly it ends up storing the extra energy as fat. This contributes to unwanted fat storage, hinders weight loss efforts and can even promote weight gain

Does Sleeping More Help You Lose Weight?

pink alarm clock in dark room
Sleep for 7-9 hours per night to maximize weight loss with phentermine

Yes, sleeping more helps you lose weight… but there’s a limit.

Sleeping too much or too little is detrimental to both health and weight loss.

To fend off an increased risk of weight gain, obesity, heart disease, stroke, type 2 diabetes and psychological distress, the American Academy of Sleep Medicine recommends 7-9 hours of sleep per night for adults ages 18-60 ( 1 ). Sufficient rest allows the brain and body time to rest, recover and prepare for the following day ( 6 ).

There is an upper limit for recommended hours of sleep per night, however, because sleeping too much causes many of the same negative health consequences as sleeping too little. Sleeping 10 or more hours a night can make you feel more sluggish and irritable than sleeping the recommended 7-9 hours ( 7 ).

So, for both health and weight loss, aim for about 8 hours of sleep most nights.

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  1. National Sleep Foundation. (2014, November 13). How to Fall Asleep Fast.
  2. Sharma, S., & Kavuru, M. (2010). Sleep and Metabolism: An Overview. International Journal of Endocrinology, 2010, 1-12. doi:10.1155/2010/270832
  3. Greer, S. M., Goldstein, A. N., & Walker, M. P. (2013). The impact of sleep deprivation on food desire in the human brain. Nature Communications, 4(1). doi:10.1038/ncomms3259
  4. Nedeltcheva, A. V., Kilkus, J. M., Imperial, J., Schoeller, D. A., & Penev, P. D. (2011). Insufficient sleep undermines dietary efforts to reduce adiposity. Annals of Internal Medicine, 153(7), 435-441. doi:10.1059/0003-4819-153-7-201010050-00006
  5. Broussard, J. L., Ehrmann, D. A., Cauter, E. V., Tasali, E., & Brady, M. J. (2012). Impaired Insulin Signaling in Human Adipocytes After Experimental Sleep Restriction. Annals of Internal Medicine, 157(8), 549. doi:10.7326/0003-4819-157-8-201210160-00005
  6. National Heart, Lung and Blood Institute. (n.d.). Sleep Deprivation and Deficiency.
  7. Johns Hopkins Medicine. (n.d.). Sleep Better.