A Good Night's Sleep Can Help with Fat Loss
Happy 2021, everybody! It is the time of the year again to set new year resolutions. How many of you have weight loss listed as one of the items on your new year's resolutions this year?
The principle of weight loss is very straightforward: to reduce energy intake and to increase energy expenditure. It may be easy to say, but the reality of the weight loss process can be frustrating. Not only shedding the extra pounds is difficult, but also it is very likely for many people to gain the bodyweight back or even more weight after they come off a diet.
In your weight loss journey, one thing that may not have crossed your mind may help to boost your weight-loss outcome: a good night's sleep. Sleep plays an important role in energy balance. Sleep deficit is linked to overweight and obesity in many ways. Here are a few studies that examined the impact of sleep deficit on body weight.
A study examined the impact of energy restriction on body weight under sleep restriction or normal sleep in 10 overweight adults for 2 weeks each treatment (1). In both sleep conditions, participants were provided with the same diet designed to meet 90% of their resting metabolic rate (Resting metabolic rate is the metabolic cost of maintaining the body at rest and accounts for 50-70% of total energy expenditure in most individuals. This study had a restriction level with potentially around 40-50% energy restriction).
The sleep intervention periods consisted of either 5.5 hours or 8.5 hours in bed. Sleep restriction resulted in less than half as much fat mass reduction compared to normal sleep. Resting metabolic rate was lower, and fasting and post-meal respiratory quotient were higher (meaning using less fat) at the end of the weight loss intervention performed in the sleep restriction compared to those of the normal sleep. Such changes would suggest that individuals with a sleep deficit would have more difficulty losing weight (lose fat) and likely have an increased risk of regaining weight post-weight loss (1).
A secondary analysis of data from three separate weight loss studies looked at whether sleep duration and quality affected the degree of weight loss achieved by caloric restriction in men and women (n=123) (2). In all three studies, participants were instructed to reduce their energy intakes by 600–700 kcal/day and were seen by a dietitian on a bi-weekly basis. Study duration ranged from 15 to 24 weeks. Sleep duration was positively associated with loss of body fat after adjusting for age, sex, baseline body mass index (BMI), study duration, and energy intake change. For each additional hour of sleep, fat loss increased by 0.77% or 0.72 kg. Sleep quality, assessed using the Pittsburgh Sleep Quality Index, was negatively related to fat mass loss, implying that lower sleep quality was related to the less fat mass loss (2).
Healthy young men (n=19 ) were randomized to either maintain their normal sleep pattern or reduce their sleep by 1.5 hours/night for 3 weeks (3). Men randomized to the sleep restriction intervention had an initial, non-significant drop in body weight, which subsequently significantly increased by approximately 1 kg over the final week of the study. The result was no difference in endpoint body weight or 3-week change in body weight between groups. In the sleep restriction group, leptin levels were maintained at baseline levels for the first 2 weeks and then decreased to below baseline by the third week (3). Leptin is an appetite suppressant hormone, which the lowered level would result in increased appetite.
The authors discussed that the extent of sleep restriction was less than some of the other clinical intervention studies (1.5 vs. 3.5–4 hour/night), thus a longer intervention duration may be required to accumulate a sufficient sleep deficit for appetite hormones and neuronal reward networks to become upregulated to stimulate appetite, food intake and ultimately weight gain (3).
Healthy young men (n=12) participated in a study with 2 days of sleep restriction (4 hours in bed) and 2 days of sleep extension (10 hours in bed) under controlled conditions of caloric intake and physical activity. Sleep restriction was associated with average reductions in the appetite suppressant hormone leptin (decrease, 18%; P < 0.05), elevations in the appetite stimulant hormone ghrelin (increase, 28%; P < 0.05), and increased hunger (increase, 24%; P < 0.01) and appetite (increase, 23%; P < 0.05), especially for calorie-dense foods with high carbohydrate content (increase, 33% to 45%; P < 0.05) (4).
As shown in rodents, food shortage or starvation results in decreased sleep, and, conversely, sleep deprivation leads to marked excessive eating. Leptin and ghrelin are peripheral signals that contribute to the central regulation of food intake. Human volunteers who slept short vs. long hours showed that sleep restriction was accompanied by increased hunger; higher circulating concentrations of the appetite stimulant hormone, ghrelin; and reduced concentrations of the appetite suppressant hormone, leptin (3, 4).
Food restriction is the most commonly used method for weight loss. Food restriction would promote hormonal changes for increased appetite. The sleep deficits, a result of our hectic lifestyles, can also bring about physiologic changes in the hormonal signals that promote hunger and crave for calorie-dense foods with high carbohydrate content foods. The sleep deficit during weight loss can sabotage the efficiency of losing weight (fat loss), and it may be one of the reasons why it is hard to lose weight, and it is easy to gain back the lost weight. Some scientists had suggested that a good night's sleep can be the future antidote to the obesity epidemic (5). I think that many people have neglected to get a good night's sleep, which may be a necessary condition to ensure your weight loss success this year.
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References:
1. Nedeltcheva AV, Kilkus JM, Imperial J, Schoeller DA, Penev PD. Insufficient sleep undermines dietary efforts to reduce adiposity. Ann Intern Med 2010; 153: 435–441.
2. Chaput JP, Tremblay A. Sleeping habits predict the magnitude of fat loss in adults exposed to moderate caloric restriction. Obes Facts 2012; 5: 561–566.
3. Robertson MD, Russell-Jones D, Umpleby AM, Dijk DJ. Effects of three weeks of mild sleep restriction implemented in the home environment on multiple metabolic and endocrine markers in healthy young men. Metabolism 2013; 62: 204–211.
4. Spiegel K, Tasali E, Penev P, Van Cauter E. Brief communication: sleep curtailment in healthy young men is associated with decreased leptin levels, elevated ghrelin levels, and increased hunger and appetite. Ann Intern Med. 2004;141:846-50.
5. Flier, J. S., & Elmquist, J. K. A Good Night’s Sleep: Future Antidote to the Obesity Epidemic? Ann Intern Med. 2004: 141(11), 885.