It’s well known that there are major benefits to getting a proper night of sleep. Increased energy, better mental focus and memory, and reduced risk of illness are just a few. But, what many people are not aware of are the ways in which sleep impacts weight loss. From food cravings to changes in hormones to less energy for activity, lack of sleep can wreak havoc on your ability to lose weight AND put you at risk to actually gain weight.
You’ve decided you want to lose a few pounds, but even with a reduction in caloric consumption, it seems like you aren’t really getting anywhere. You increase exercise, and same results. It’s time to look at your sleep patterns. The Center for Disease Control reports that 35% of Americans are sleep deprived. Getting less than 7 hours of sleep per night (yes, that’s right, you need MORE than 7 hours of sleep a night) can lead to a reduction in your ability to lose weight. The Annals of Internal Medicine ran a study where they restricted half of the participants’ sleep to only 5 and a half hours of sleep per night, while the other half got over 8 hours of sleep per night. Both groups were on the exact same diet, but the group with reduced sleep only lost half of the fat lost by the other group, while also losing more lean mass. They also reported feeling hungrier than the group with proper sleep.
There is an increasing amount of research that shows that people who sleep less, weight more. A study conducted by Stanford University in partnership with the University of Wisconsin concluded that the less people sleep, the more they weigh. The study followed 70,000 women for 16 years. The conclusions were that women who slept less than 5 hours a night weighed more than those who slept 7 hours a night. Women who sleep 5 hours per night are 1/3rd more likely to experience weight gain of 33 pounds or more and 15% more likely to become obese than those who sleep 7 hours. Women who sleep 6 hours a night are 12% more likely to gain 30 or more pounds, and 6% more likely to become obese than those who sleep 7 hours. The most outstanding part is that the women who slept less, did not eat any more.
Your metabolism likes sleep. Sleeping enough will not lead you to lose weight. But, not enough sleep stifles your metabolism and can contribute to weight gain. Sleep deprivation makes you “metabolically groggy” researchers at the University of Chicago of found. After only 4 days of improper sleep, your body’s ability to properly utilize insulin goes off kilter. Insulin is a hormone needed to turn sugar and starches into energy. Like a taxi, insulin picks up glucose (blood sugar) and delivers it to cells. The cells recognize the taxi and take in the glucose to use for fuel. Insulin also shuttles extra glucose to the liver and muscles for storage as glycogen and as fat in adipose cells. Insulin sensitivity is how efficiently your body allows taxis to stop and deliver glucose. When insulin sensitivity decreases, glucose doesn’t transfer into the cell, but remains in the taxi, circulating in the blood and denying cells of fuel. The researchers found that less than a week of sleep deprivation reduced insulin sensitivity by 30%. In an effort to get glucose into cells, your body releases more insulin into the bloodstream, leading to elevated insulin levels. which can tip the scales for the glucose to be taken to fat cells for storage… Leading to weight gain.
There are other hormones that are impacted by low sleep as well: ghrelin and leptin. Ghrelin is the hormone that tells your brain when you are hungry and need to eat. Produced by special cells in the stomach and pancreas, ghrelin is released into your bloodstream when your stomach is empty. It travels to the hypothalamus triggering hunger signals. When you eat, your stomach fills with food and ghrelin levels subside. Leptin is a hormone secreted by adipose tissue (fat cells) and similar to ghrelin, it travels to the hypothalamus via the bloodstream. However, leptin signals you to experience a general reduction in appetite and stop eating. Speigel and colleagues found that moderate sleep deprivation resulted in decreased leptin levels. Participants were also found to have increased ghrelin levels with concurrent increases in appetite, hunger and desire to consume carbohydrate rich, calorie-dense foods. This disruption in ghrelin and leptin balance from too little shut-eye sets you up to battle hunger and cravings for calorie-rich foods. With your brain telling you to eat more with milder fullness signals, you are cued to consume more, likely leading to weight gain. The effects of reduced leptin levels don’t stop at fullness cues. Researchers also suspect that lower leptin levels lead to a reduction in energy expenditure. In studies that examined the effect of caloric restriction on leptin levels, researchers found that decreased energy intake resulted in lower leptin levels and a concurrent reduction in daily overall energy expenditure.
When tired, the reward centers of your brain get stimulated, leading you to crave sugar, fats, and other quick calories. The reward system of your brain consists of the neural pathways and brain structures responsible for motivation, desire, wanting and cravings. These are all elements of reward related cognition (the ability to home in on, go after and gain positive emotions from rewards), which is an important part of survival for animal species. The three essential parts of reward cognition are that it creates associative learning (which is almost all types of learning) , affects decision making, and elicits positive emotions.
Researchers at the University of Chicago found that the brain chemical, 2-AG, is elevated in sleep deprived people. 2-AG, or 2-Arachidonoylglycerol, is a neurotransmitter which lends a hand to a wide variety of bodily functions. It is also part of the endocannabinoid (eCB) system, which are a series of receptors throughout the brain and central nervous system that are involved in a variety of physiological processes including appetite, mood and pain sensations. The endocannabinoid system is a key player in appetite and energy levels.
When this 2-AG is increased, it excites the reward system in our brain, increasing our drive to seek pleasure, including tasty foods. The researchers found a correlation between a 2-AG stimulated reward center and greater motivation to eat carbohydrate and fat rich foods. When we are sleep deprived, our hedonic drives increase, leading us to be more likely to reach for unhealthy foods and consume those foods in larger amounts.
When researchers compared 2-AG levels in sleep deprived individuals to those of well rested individuals, they found that the 2-AG levels in sleep deprived people rose higher and stayed higher throughout the evening. As a result, the sleep deprived group had a harder time resisting snacks than the well-rested group.
A University of California Berkeley study also found that the frontal lobe of the brain is impaired when sleep deprived. The frontal lobe is the part of the brain that makes decisions. Blunted decision making and increased desires lead us to make poorer food choices and overeat. The Berkeley study also found that the tired participants were much more likely to choose junk food over healthier options and typically went for higher calorie foods.
Lack of sleep discourages exercise. When we are tired, it is hard to get through a day, let alone get to the gym. This often leads us to miss workouts. Researchers found that sleep deprived individuals are less likely to choose to engage in activities that require extra physical effort. Researchers examining the effect of exercise on women with insomnia found that the women who slept fewer hours at night exercised for a shorter period of time the next day. The reduction in next day exercise duration increased as the total number of hours of sleep decreased. Exercise naturally boosts energy levels, burns calories, and improves our mental and physical health.
Muscle helps to burn fat. But lack of sleep leads us to burn muscle for more energy. What this means is if we are not exercising, we are not maintaining or gaining muscle. Add in that lack of sleep will burn up some of the muscles we already have, and muscle mass will decrease. Sleep debt decreases your protein synthesis, which is how your body makes muscle. So, not only is your body burning muscle by not sleeping, you are also decreasing your ability to make it.
Lack of sleep also blunts your body’s ability to recover from exercise, which is likely to lead you to exercise less frequently. Poor sleep slows down the production of growth hormones, which help your body to recover from exercise and burn fat. Lack of sleep also increases your body’s level of cortisol, the stress hormone, further reducing the production of growth hormones. A longer recovery time ultimately results in your subsequent workouts being much more challenging.
The National Institutes of Health has found that time to exhaustion during exercises decreases and perceived exertion increases with sleep deprivation. So, you are likely to feel like you are working out harder than you are and less likely to work out for very long. Your maximum energy levels will be lower, as will your average energy levels. Exercising can actually improve your ability to sleep well, so there is the ability for a positive feedback loop there. If you are sleeping better, you are more likely to exercise, and that exercise is likely to improve how well you rest.
Lack of exercise, hormonal changes, and food cravings from lack of sleep are all putting one at risk for weight gain. Sleep deprivation impacts our bodies very quickly. After a few nights of sleep deprivation, a University of Colorado study shows, weight gain can occur. Sleep researchers tracked a small group of men and women for 2 weeks, monitoring their sleep, food intake and metabolism. They wanted to see how just a single week of sleep deprivation might impact a person’s health. What they found was that participants sleeping only 5 hours a night gained an average of 2 lbs in a single week. Not only were the participants increasing their food intake to offset sleep, but also reaching for more carbohydrates. Once they went back to sleeping more, they began to make healthier food choices again.
The CDC has reported that 36% of Americans are obese. That is about the same percentage of Americans that they reported to be sleep deprived. A high population study has shown that both children and adults are more likely to be obese due to lack of sleep. A study of almost 700,000 people worldwide ranging from age 2 to 102 showed that short sleep duration greatly increased the likelihood of being either overweight or obese.
Finally, it also appears night owls are at a risk for weight gain. A study done by Northwestern University found that regularly going to bed late, sleeping late and eating late leads to an increase in weight. It also showed that the late sleepers were more likely to eat more fast food and less fruits and vegetables. These late sleepers were found to consume more calories overall and have higher BMIs. The study shows that it isn’t just the number of calories that you eat, but when you eat them. “Human circadian rhythms in sleep and metabolism are synchronized to the daily rotation of the earth, so that when the sun goes down you are supposed to be sleeping, not eating,” noted senior author Phyllis Zee, M.D., professor of neurology and director of the Sleep and Circadian Rhythms Research Program at Feinberg. “When sleep and eating are not aligned with the body’s internal clock, it can lead to changes in appetite and metabolism, which could lead to weight gain.”
Shifted sleep schedules from our normal rhythms and altered sleep times can definitely impact our weight and the likelihood of weight gain.
The importance of sleep on our overall health should be taking very seriously. It impacts everything from memory to energy levels to weight loss. Sleep is a hugely important part of creating a healthy lifestyle that often gets neglected when life gets hectic. Getting over 7 hours of sleep and getting to bed at the correct hour will help us to make better food choices, to feel better and more energized and to keep our hormones naturally regulated. All of this will set us up for a healthier body weight and reduce the likelihood of food cravings and binges.