“Sleep more, lose more fat!” sounds like the kind of nonsense you’d expect from an infomercial or faddish fat loss book, but it’s not. New research shows that not getting enough sleep could have a significant adverse effect on your attempts to lose fat. If you’re one of those folks who sleeps six hours or less each night and thinks nothing of it, then read on.
Less Sleep = Less Fat Loss
Numerous epidemiological studies have detected a correlation between overweight and poor sleep habits, but it wasn’t until recently that the association was confirmed with data from a real live clinical trial.
In this trial, ten overweight men and women spent two separate 14-day periods on a calorie restricted diet. In one of these periods, they spent 8.5 hours each night in bed, while in the other they spent only 5.5 hours under the sheets. In order to have full control over the subjects’ bedtime hours and dietary intakes, the researchers housed them in a metabolic ward.
The researchers’ primary interest was whether the difference in sleep duration would affect the amount of fat and lean mass lost during calorie restriction. The researchers also measured changes in fat utilization, energy expenditure, hunger, and 24-hour hormone concentrations.
The mean self-reported habitual sleep duration of the subjects prior to the study was 7.7 hours per day. Mean actual sleep duration during the study was 7 hours 25 minutes in the 8.5-hour time-in-bed phase, and 5 hours 14 minutes in the 5.5-hour phase.
The subjects consumed a mean 1450 calories during each phase. There were no differences in total daily energy expenditure in either condition (2136 vs. 2139 calories during the 8.5-hour and 5.5-hour phases, respectively).
Extra Sleep Burns Fat, Saves Muscle, Decreases Hunger
Both treatments were accompanied by similar weight loss (approximately 3 kg); however, more than half of the weight loss during the 8.5-hour time-in-bed condition and only one quarter of the weight loss during the 5.5-hour time-in-bed condition was fat (1.4 vs. 0.6 kg).
If total weight loss was the same but the longer-sleep phase resulted in more fat loss, that could only mean one thing: the short-sleep phase caused more lean mass loss. Indeed, when the researchers measured the loss of fat-free body mass, it was 60% greater during the 5.5 hour time-in-bed condition (1.5 kg versus 2.4 kg for the 8.5 vs. 5.5-hour phases, respectively).
The subjects also reported increased hunger during the period of sleep restriction.
Fasting and post-meal respiratory quotient was higher at the end of the 5.5-hour time-in-bed condition, indicating reduced fat-burning. Levels of the hormone ghrelin were also increased. Ghrelin has been shown to reduce energy expenditure, stimulate hunger and food intake, promote retention of fat, and increase glucose production in the liver.
In contrast, resting metabolic rate and 24-hour plasma epinephrine concentrations were lower at the end of the 5.5-hour time-in-bed condition. Leptin concentrations declined in parallel with the loss of weight and adiposity without a significant independent effect of sleep duration. No differences were observed between phases in the thermic effect of food, nor 24-hour norepinephrine, cortisol, growth hormone, and thyroid hormone concentrations.
Waking Up to the Importance of Sleep
This study shows that insufficient sleep can partly sabotage the beneficial effects of a calorie-restricted weight loss diet, by reducing the amount of fat lost and instead increasing the amount of lean tissue catabolized by your body as it struggles to meet its energy needs.
The researchers postulated that the increased loss of fat-free body mass during the short-sleep condition “may have been due to increased conversion of body protein into glucose to support the more prolonged metabolic needs of the waking brain and other glucose-dependent tissues”.
Another point to keep in mind is that this was a free-living study in which the food intake of the subjects was controlled. As both this and a previous study reported increased hunger and ghrelin levels as a result of sleep restriction, free-living individuals who skimp on sleep may be hit with a double-whammy: greater muscle loss and increased fat gain resulting from a heightened calorie intake!
Late night Internet surfing, television, nightclubbing, shift work and various other activities are keeping many people awake when they should be in bed sound asleep. If you want to optimize your body composition then staying up late reading inane crap on Facebook or watching late-night infomercials isn’t the way to do it. Your computer and TV will still be there in the morning, so turn them off and get to bed at a decent hour.
Rhythm’s Gonna Get You
Along with iron reduction, sound sleep is unquestionably one of the most valuable yet severely underrated health improvement strategies in existence. And unlike iron reduction, which is contraindicated for certain groups (namely, those with anaemia and iron deficiency), everybody needs sound sleep. It is during sleep that the body’s growth and repair processes really get swinging. In fact, your health and well-being is under the overriding influence of what is known as the circadian rhythm. This is the critically important 24-hour pattern of neurotransmitter and hormone release governed by the night-day/sleep-wake cycle.
Nature wants you exposed to bright light during the day, but falling asleep well before midnight in the darkest, quietest possible surroundings. Among other things, this produces the highest night time levels of melatonin, the hormone responsible for sound sleep and purported to have potent anti-cancer, immune-enhancing effects.
Messing with your natural circadian rhythm can have severe consequences. Lack of sleep and/or poor sleep quality suppresses immune function, impairs glycaemic control, decreases energy and alertness, worsens mood and cognitive performance, and increases the risk of chronic disease. Bad sleep habits are well worth avoiding.
To maximize melatonin release, avoid dinners with a high protein:carbohydrate ratio. Protein raises levels of excitatory neurotransmitters, whereas high-carb meals boost blood levels of tryptophan, which in turn boots serotonin, which then raises melatonin levels. Forget the whole “don’t eat carbs after 6pm” dogma – not only is it utter nonsense with absolutely no foundation in scientific reality, but it’s a surefire path to restless sleep.
Make your sleeping environment as dark as possible, and remove all sources of white, green and blue lighting from your room, as these are especially effective at suppressing melatonin (devices with red illumination are OK, as red light has minimal impact on melatonin).
Anthony Colpo is an independent researcher, physical conditioning specialist, and author of the groundbreaking books The Fat Loss Bible and The Great Cholesterol Con. For more information, visit TheFatLossBible.net or TheGreatCholesterolCon.com
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