We’ve all heard that not getting enough sleep could hamper your efforts to lose weight or even make you gain weight.
Now researchers have put a figure on it – getting less than five-and-a-half hours of sleep each night could see you put on nearly 14lbs. in one year. That extra weight is likely to creep on even if your diet and activity levels remain exactly the same.
The changes in your body’s metabolism as a result of lack of sleep are responsible for the change, and could go some way to explaining why people get larger as they get older and struggle to sleep. Night shift workers who have problems sleeping during the day are also likely to be overweight.
During the study, volunteers’ sleeping habits were watched and influenced for six weeks. Participants were first allowed 10 hours of sleep each night, before this was reduced to five-and-a-half hours during the day.
The researchers from Boston in the U.S. discovered that the metabolism rate dropped by 12% when lacking sleep; this rate is the standard needed to continue the body’s normal functions.
When the rate falls, the body uses fewer calories to maintain bodily functions, meaning less fat is burned. The volunteers sleeping for just five-and-a-half hours on average burned off 120 calories fewer each day. Over a year, this would lead them to put on just under a stone (12.5 pounds).
Night shift workers are also more prone to diabetes and obesity as a result of the shift in body clock which means they struggle to sleep during the day.
Study author Dr Orfeu Buxton said: “Since night workers often have a hard time sleeping during the day, they can face both circadian disruption working at night and insufficient sleep during the day.
“Getting enough sleep is important for health, and sleep should be at night for best effect.”
Getting more sleep can help you burn fat
Lack of sleep creates a hormone imbalance which serves to increase the appetite and encourage you to put on weight. Even partial sleep deprivation can play a part in weight gain, say researchers.
The good news is that the opposite is also true: a good night’s sleep could have a significant impact on the fight against obesity, and could actually help you burn fat.
Researchers at Pennsylvania State University in the U.S. discovered that a quarter of Americans get less than six hours sleep each night – which may go some way to explaining why so many Americans are now considered to be obese.
While current weight loss recommendations focus on promoting exercise and changing diet, improving an individual’s sleep patterns could actually help significantly, says Sharon Nickols-Richardson, professor of nutrition.
She says: “Various investigations, although diverse, indicate an effect of partial sleep deprivation on body weight management. The intriguing relationship between partial sleep deprivation and excess adiposity (body fat) makes partial sleep deprivation a factor of interest in body weight regulation, particularly in weight loss.”
The researchers reviewed research papers from the past 15 years and created comparative tables on a series of factors such as energy intake, energy expenditure, hormone measurements and more in order to identify any patterns.
They discovered an increase in the hormone ghrelin and a decrease in the hormone leptin among partially sleep deprived people; these two hormones help to influence energy intake.
Prof Nickols-Richardson added: “Changes in these hormones coinciding with an energy-reduced diet paired with changes in response to partial sleep deprivation may be expected to increase ghrelin and decrease leptin concentrations even further to promote hunger.”
Lack of sleep could also make you eat more
If you’re sleep deprived, you’re likely to eat more food and the extra calories you take in as a result can lead to weight gain and obesity.
Researchers from the Mayo Clinic in Rochester, Minnesota, discovered that a sleep-deprived group of volunteers, who on average slept for an hour and 20 minutes less than a control group, ate an extra 549 calories on average each day.
At the same time, the amount of energy used for daily activities didn’t change significantly between the two groups, suggesting those who slept for less time each night didn’t even burn any additional calories.
The study suggests the importance of a good night’s sleep when trying to stick to a healthy eating regime.
“Sleep deprivation is a growing problem, with 28 per cent of adults now reporting that they get six or fewer hours of sleep per night,” said co-investigator of the study, Andrew D. Calvin, cardiology fellow and assistant professor of medicine at the Mayo Clinic.
“We tested whether lack of sleep altered the levels of the hormones leptin and ghrelin, increased the amount of food people ate, and affected energy burned through activity,” added Virend Somers, study author and professor of medicine and cardiovascular disease at the Mayo Clinic.
They found that the participant’s lack of sleep was associated with increased leptin and decreased ghrelin, both of which are connected to appetite.