Inflexible metabolism can increase the risk of obesity during sleep
Throughout the day, we gain energy by breaking down carbohydrates, fats, and proteins in our body through the process of metabolism. For example, right after we eat, most of our energy comes from carbohydrates, while after fasting most of it comes from fat.
The body’s ability to change metabolic energy sources in response to changes in nutritional status, such as after meals and during sleep, is called metabolic flexibility.
Research has shown that disrupted flexibility, or inflexible metabolism, is associated with diseases such as obesity and diabetes. People with inflexible metabolisms burn less fat at night than those with flexible metabolism, and the research team measured their respiratory rate throughout the night and found that, despite their age, their BMI (Body Mass Index) and amounts of fat, people with inflexible metabolism burned more carbohydrates and less fat than people with flexible metabolisms.
Moreover, the higher sleep coefficient could be a previously unknown indicator for the risk of future metabolic disease. “We were interested in how metabolism changes during sleep and whether we could detect metabolic differences in people with inflexible metabolisms,” explains Professor Kumpei Tokuyama.
The basic method used by the research team focused on a measurement called respiratory coefficient, abbreviated CR, which measures how much oxygen we use and how much carbon dioxide we breathe. Equal amounts (CR equal to 1) indicate that the source of energy is carbohydrates. A lower ratio, around 0.8, suggests that fats or proteins are used as an energy source. To characterize metabolic changes over time, the researchers measured carbon dioxide / oxygen ratios in 127 people every five minutes over a 24-hour period.
The first discovery was unexpected. Because sleep is like a period of fasting, CRs could be expected to decrease overnight, indicating that fat has been burned more and more as sleep progresses. Instead, they found a different pattern.
“We were surprised to find that while CR values dropped steadily at the beginning of sleep, after reaching a low point they began to return after midnight and continued to rise until people woke up,” says the professor. Tokuyama.
Then, the team separated the participants according to how varied their CRs were. High variability means that the metabolism is flexible, with CR values increasing and decreasing depending on the body’s needs throughout the day. After dividing participants into flexible and inflexible metabolic groups, the team found that although mean CRs over 24 hours were the same between groups (same as age, BMI, and body fat), time CRs at night were higher for those with less flexible metabolisms, indicating that participants burned more carbohydrates than fat.
These findings have the potential for practical use, as Professor Tokuyama explains: “Prevention of diseases such as obesity and diabetes is much preferable to their treatment. Annual controls that focus on measuring CR values in sleep could help detect people at risk of developing metabolic diseases, thus enabling timely interventions. ”
Metabolism can also work optimally through a balanced diet and regular physical activity, and in the Dahna app, created by cardiologists and nutritionists, you can learn more about how to stay fit. You can download it for free from the App Store or Google Play .