Disrupted sleep could be telling your body to hold onto fat. Yes, that’s right Mzansi, a team of Japanese researchers from the University of Tsukuba have shown that people with inflexible metabolisms are burning less fat at night than those with flexible metabolisms. And it has to do with your sleeping habits.
The body has an ability to switch between different energy sources in the body (from carbohydrates to fat, for instance). When it makes a switch in response to changes in nutritional state, such as after meals and during sleep, it is called “metabolic flexibility”.
New research published in the Scientific Reports suggests that too little or irregular sleep can decrease this flexibility, and that this disrupted flexibility is associated with diseases such as obesity and diabetes.
People who sleep less burn more carbs, less fat
The team, led by Professor Kumpei Tokuyama, measured the respiratory quotient throughout the night and found that despite equal ages, BMIs and amounts of fat, people with inflexible metabolisms burned more carbohydrates and less fat than people with flexible metabolisms.
The respiratory quotient, abbreviated as RQ, measures how much oxygen we use and how much carbon dioxide we breathe out.
The findings were unexpected
Tokuyama and his team of researchers at the University of Tsukuba have been studying metabolism during sleep.
“We were interested in how metabolism changes during sleep and whether we could detect any metabolic differences in people with inflexible metabolisms.”
Throughout the day, we gain energy by breaking down carbohydrates, fats and proteins in our bodies through the process of metabolism. For example, immediately after eating, most of our energy comes from carbohydrates, while after fasting, most comes from fats.
The higher sleep-time quotient could be a previously unknown indicator for the risk of future metabolic disease.
To characterise metabolic changes over time, the researchers measured the carbon dioxide-to-oxygen ratios from 127 people, every 5 minutes over a 24-hour period.
Because sleep is like a period of fasting, it could be expected that RQs would decrease all night long, indicating that fat was being burned off more and more as sleep progressed. Instead, researchers found a different pattern, Tokuyama notes.
“We were surprised to find that while RQ values decreased steadily at the beginning of sleep, after reaching a low point, they began to rebound after midnight and continued to increase until people woke up,” says Tokuyama.
After dividing participants into metabolically flexible and inflexible groups, the team found that even though average RQs over 24 hours were the same between the groups (as were their ages, BMIs and amounts of body fat), RQs at night were higher for those with less flexible metabolisms, indicating that the participants were burning more carbohydrates than fat.
These findings have the potential for practical use, Tokuyama explains.
“Preventing diseases such as obesity and diabetes is much preferable to treating them. Yearly check-ups that focus on measuring sleeping RQ values could help screen for people at risk for developing metabolic diseases, thus allowing timely interventions.”
It’s important to get plenty of sleep
Sleep deprivation is a global phenomenon, says the World Sleep Society, a non-profit organisation of sleep professionals dedicated to advancing sleep health worldwide.
“Sleep problems constitute a global epidemic that threatens health and quality of life for up to 45% of the world’s population,” the society says.
A 2010 study also suggests that sleep deprivation can alter the way you break down sugar and your hormone levels. Hormones are involved in regulating your metabolism as well as your appetite and your body’s fat storage.
This video provides ten tips on getting better sleep.