by Nashville personal trainer Dan DeFigio
When people low on sleep find their energy dropping, many turn to food for a pickup. The short-term rise in blood sugar gives a more energetic feeling, but often the extra calories are unneeded and stored as body fat.
A lack of sleep changes hormone levels and thus influences weight gain. For instance, higher levels of insulin – a condition known as insulin resistance, or "pre-diabetes" – have been linked to a shortage of sleep. Since excess insulin promotes fat storage, extra insulin could make weight loss more difficult.
Furthermore, the most appealing foods when we feel low on energy are often sweets or refined carbohydrates with low nutrient density, like cookies. Since sleep deprivation promotes insulin resistance, overconsuming these types of carbohydrates worsens the problem.
Tired people may burn fewer calories, too, because they move around less and are often too fatigued to exercise. Or if they do manage to exercise, they work out less intensely than usual.
In a Japanese study of six- and seven-year-olds, children who slept nine to 10 hours a night were compared to those who slept only eight to nine hours – just one hour difference. The latter group was almost twice as likely to be overweight. Children sleeping less than eight hours a night were almost three times as likely to be overweight.
The University of Chicago Medical Center reported in a 1999 issue of The Lancet that cutting back from the standard eight down to four hours of sleep each night produced striking changes in glucose tolerance and endocrine function – changes that resembled the effects of advanced age or the early stages of diabetes – after less than one week.
"We found that the metabolic and endocrine changes resulting from a significant sleep debt mimic many of the hallmarks of aging," said Eve Van Cauter, PhD, professor of medicine at the University of Chicago and director of the study. "We suspect that chronic sleep loss may not only hasten the onset but could also increase the severity of age-related ailments such as diabetes, hypertension, obesity and memory loss."
Recent studies in humans have shown that the levels of hormones that regulate appetite are profoundly influenced by sleep duration. Sleep loss is associated with an excessive increase in appetite. This is because the regulation of leptin, a hormone released by the fat cells that signals satiety to the brain and thus suppresses appetite, is markedly dependent on sleep duration.
In conclusion, the research shows that lack of adequate sleep increases appetite, decreases activity, increases insulin resistance, and increases the release of stress hormones. This combination of factors promotes fat storage and makes it difficult to lose weight.
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