Written by Dan Gwartney, MD
01 November 2011

Sleep Your Way to Fat Loss


Weight-loss gurus on television advise “exercise more” and “eat less,” as though these statements should have been included in the original 10 Commandments. There is a principle in logic called ‘Ockham’s Razor,’ which tells us that the simplest solution is usually the correct one. Well, what could be simpler than exercise more, eat less? Unfortunately, even Ockham’s Razor is not that simple. Friar William of Ockham stated that when making a choice, any assumptions that do not make a difference should be excluded; however, it is vital to include assumptions that are relevant.

Step away from the high-tech world of liposuction, gastric bypass, appetite suppressants, thermogenic and lipolytic drugs; the human body adapts to its environment. At the most basic level, that includes the amount of food available, the amount of activity needed to acquire that food, and the amount of rest one can obtain before needing to forage again.

Sleep is an under-appreciated need in American society. In fact, society often rewards individuals who forego sleep in order to work longer hours, party harder, watch adult entertainment and enjoy the ‘night life.’ People go to great lengths to eradicate the need for sleep. It is not just post-adolescent ravers taking methamphetamines and ecstasy to prolong nights of hedonism; the ranks of the sleep-deprived are filled with students and professors using Adderall® to allow for academic all-nighters; physicians and nurses using Provigil® to stay sharp during careers of extended hours; policemen and power plant workers walk the health store aisles looking for energy supplements that will get them through rotating shifts; children guzzle Red Bull® to pwn [sic] friends and strangers through early morning online gaming; and mothers brew coffee every morning to meet the demands of family.1-5

Prior to the information age, most jobs were labor or service related; social norms were more conservative and people were praised for being practical, not outrageous or risk-taking. One popular axiom was “Early to bed, early to rise, makes a man healthy, wealthy and wise.” These observations would suggest that previous generations may have actually hibernated. In fact, sleep patterns were not overly different from today, on a day-to-day basis. Of course, leisure time has been extended and the introduction of electric lighting and varied forms of entertainment remove many of the cues that would normally send one to sleep. Most conventioneers can attest to the temporal (time) confusion experienced inside the casinos of Las Vegas where fluorescent lights and the absence of clocks mask the passage of time.

Nonetheless, there has been an overall trend toward sleep deficit. In comparison to several decades ago, Americans are sleeping, on average, 90 minutes less per night.6 An hour or two makes little difference in the short-term, but over time, a chronic sleep deficit dramatically affects one’s health. A number of studies have shown that sleep deprivation results in reduced cognitive function (thinking), hormonal changes, negative changes in blood pressure, worsened insulin sensitivity, etc.7-9

In fact, during the recent daylight savings time-related time change, news channels reported the findings of a 2008 Swedish study published in the New England Journal of Medicine, showing that the risk of a heart attack increases 5 percent during the three days immediately following the ‘spring forward’ change that results in the loss of an hour’s sleep for most. Conversely, there was a smaller reduction in risk during the three days following the ‘fall back’ that gifts an extra hour of sleep. The authors posited that the increase in heart attacks following the loss of an hour of sleep was due to an increase in sympathetic tone (adrenalin) and a pro-inflammatory state.10 These factors are already elevated in the obese, making the time change very risky in this group.11 Perhaps it is time for the FDA to review daylight savings time.

Sleep Deprivation and Obesity

Sleep deprivation does not just increase risks associated with obesity, but it also increases the risk of obesity. Several studies have associated sleep deprivation with obesity, as well as the Metabolic Syndrome, which includes negative changes to cardiovascular health and insulin sensitivity, and changes in hormones that promote fat storage.12 Even as this article is being written, new studies are linking sleep deprivation with poor health. Research is being presented at the American Heart Association, reporting an increase in the risk of developing type II diabetes in people who sleep less than 6 hours per night, compared to those who sleep 6 to 8 hours.13

Is there more to the inverse association between sleep loss and weight loss than metabolic and hormonal changes? Could the increased number of waking hours somehow relate to foraging behavior as well? After all, except for the rare case of somnambulist bingers (those who sleepwalk to the refrigerator to eat), people don’t break their diet while they are asleep.14          

Researchers investigated the effect of shorter daily sleep with food intake, confirming what many suspected— people who stay awake longer tend to be sedentary during those additional waking hours and increase their food intake by snacking. Look at the question from a personal perspective— late-night study sessions require pizza and Mountain Dew®; Left 4 Dead gamers down energy drinks and chips while waiting to be re-spawn; dates and parties take place over dinner, drinks and hors d’oeuvres; movie marathons require popcorn and Good & Plenty candy.

Anecdotal rumors of culture-wide, dark-dependent gluttony do not constitute scientific evidence; thus, Dr. Nedeltcheva and colleagues at the University of Chicago recruited 11 non-obese subjects who agreed to be followed in a controlled environment for 14 days on two separate occasions, in a study published in the American Journal of Clinical Nutrition.15 These five women and six men were healthy, normal individuals who were not actively trying to lose weight and did not exercise. During the study periods, they were allowed to follow a normal routine, including normal leisure activities such as watching television, reading, using the Internet, etc; access to food was unlimited. They were not allowed to leave the observation area for more than 30 minutes a day. Prior to each two-week ‘vacation,’ scientists measured 24-hour energy expenditure, total calories consumed (divided into meals and snacks), and the appetite-regulating hormones leptin and ghrelin.

 The study periods differed only in the number of hours of sleep allowed to the subjects; no naps were allowed at any time. During one session, subjects slept 8½ hours daily for the 14 days; during the second, they only slept 5½ hours per day. Surprisingly, there was not much difference in the total energy expenditure when these subjects were awake 3 hours more. Considering that the activity options were limited to normal, couch-potato activities, this shows that there is not a lot of difference metabolically between sitting on the couch versus sleeping. The appetite-regulating hormones, leptin and ghrelin, were similar between the groups as well. Of course, there was no calorie-restriction, so the subjects never experienced periods of hunger or starvation during this time.

 The subjects were not provided with diet guidelines; they ate what they wanted and were provided with snacks of their choice throughout the study. As might be expected, with no restrictions and little to focus on, the subjects ate plenty. On average, the amount consumed during the three meals (breakfast, lunch and dinner) was similar during the two study periods. The macronutrient profile of the meals was typical American fare, with an approximate 52:34:14 ratio of carbohydrate:protein:fat by calories. The primary difference seen between the sleep-deprived state and sleep-aplenty state was in calories consumed as snacks. When restricted to 5½ hours of sleep daily, subjects consumed significantly more calories during snack time and tended to increase carbohydrate content of these snacks. Most importantly, the biggest difference was seen in snacking occurred between 7 p.m. and 7 a.m.15 It is believed that access to and temptation of snacks is a deciding factor in dieting success.

 All subjects consumed in excess of the number of calories expended, eating more than 1,000 calories in excess every day when rested (1,012 calories during the 8½ sleep daily period). When sleep was restricted to 5½ hours for 14 days, 1,173 calories were consumed in excess. Those numbers (calories in excess) were calculated by measuring the food intake and subtracting the measured daily energy expenditure, so the number is as accurate as possible. Thus, when 2-3 hours of sleep deficit occurred, subjects consumed more food that resulted in an additional 161 calories per day; 161 calories above a baseline that was already over 1,000 calories in excess.

Lost Sleep is Lost Muscle

The question that logically follows is: did the additional calorie burden result in weight gain, or more importantly, fat gain? The subjects underwent both regular weigh-ins and DXA scans to measure body composition. Not surprisingly, subjects gained a similar amount of weight during both periods, approximately 2 kg; this follows the study design of sedentary conditions supplemented with freely available food.

Though the results were not significant, there was a noticeable trend in the character of that weight gained. During the 8½ hour sleep period, subjects gained (on average) 2.1 kg with 1.5 kg being fat— 71 percent. When restricted to 5½ hours of sleep, 1.9 kg weight gain was recorded, with 1.7 kg arising from fat gain— almost 90 percent. The authors did not comment on this observation, but it appears to suggest that the ‘stress’ of losing sleep is catabolic to lean mass (muscle). Given that the subjects consumed a similar amount of protein, the sleep-deprived conditions included a greater amount of calories, and the consumption of more carbohydrates would maintain a higher insulin concentration, one would expect that muscle would be better preserved and the sleep-deprived conditions would lead to equivalent changes in body composition, if not a preference to lean mass gains. Instead, the opposite was seen. Another explanation may be that adequate sleep promotes anabolic processes, allowing muscle to be maintained or increased when adequate rest is obtained.

 It is likely no coincidence that as sleep hours have decreased society-wide, Americans have become fat and are developing metabolic conditions that are threatening the stability of the national health system. An impressive body of evidence is being reported, associating the loss of sleep with a number of health risks. Yet, people still burn the midnight oil, determined to squeeze the last bit of productivity or enjoyment out of each day if it kills them. Guess what? It might.16 Don’t sleep in though— too much sleep can be just as bad for you. For all the people who are attempting to lose weight to attract Mr. Right or Ms. Sweetheart, those late nights are taking a toll, not just on one’s health and lifespan, but also on the ability to be a hard body. Grabbing a good night’s sleep regularly is vital to promoting optimal weight management. Perhaps more relevant to the man or woman working to improve his/her physique is the negative impact those extra hours have on fat gain. Slip between the sheets for your daily eight and if conditions require you to stay awake longer, put away the snacks.