When we're cold, we shiver. The involuntary vibrations help us generate body heat so that we don't freeze. And all that motion also has a secondary benefit for modern humans — it burns calories, and potentially fat. Can we really shiver our way to better health? It almost sounds like a pitch from an informercial, but it's true: one study from found that just 15 minutes of shivering might provide similar fat-burning benefits as a full hour of moderate exercise.
Our instinctive response to the cold helps stimulate a key hormone called irisin that helps the body produce a specific type of fat conducive to weight loss. Simply being cold doesn't translate to sustained weight loss.
Dubbed the "exercise hormone" because our bodies seem to release it in response to physical activity, irisin helps turn white fat into brown fat in our bodies.
That matters because brown fat is easily turned into energy by the body's mitochondria stores, meaning it's easier to burn off. And sure enough, irisin is present in our bodies when we shiver, just like when we exercise, meaning that unpleasant shaking sensation can indeed help us burn fat.
In a Cell Metabolism study from , 10 volunteers dressed in hospital scrubs and laid under water-cooled blankets used to adjust their body temperature. They started at 27 degrees Celsius More intense shivering correlated with higher levels of irisin production.
When compared to another group of test subjects cycling on stationary bikes, the researchers found shivering for just 15 minutes resulted in irisin levels comparable to those seen after 60 minutes of moderate exercise. Of course, the simple act of shivering itself burns some calories, too, though it's unclear if it's enough to make much of a difference. During a 1-hour ride at an easier level, irisin levels rose about 3-fold, confirming the ability of exercise to increase irisin secretion in humans.
The team next looked at the impact of cold exposure on irisin levels. While their core temperature was maintained, their skin temperature dropped. Irisin secretion increased proportionally to shivering intensity. The increase was similar in magnitude to the exercise-stimulated secretion.
The team also found that the secretion of fibroblast growth factor 21 FGF21 , a hormone associated with brown fat activation, was affected by exposure to cold. The researchers next tested human fat cells taken from biopsies of the neck area. These changes were not noted in fat cells taken from other regions of the body that tend to be rich in white fat. Although this was a small clinical study, the findings suggest that exercise-induced irisin secretion could have evolved from shivering-related muscle contraction.
The results also suggest that since activation of these pathways results in greater energy expenditure, the pathways may serve as potential therapeutic targets for obesity and related conditions. We use cookies and other tracking technologies to improve your browsing experience on our site, show personalized content and targeted ads, analyze site traffic, and understand where our audiences come from.
To learn more or opt-out, read our Cookie Policy. As the temperature drops this time of year, the rich, comfort foods of winter seem just right. But as we lay about, full from our heavy winter meals, we may also dream about how to quickly burn off those extra calories. One idea that gets bandied about is that all you have to do is exercise outside in the cold.
It is true that a cold body uses more energy to keep itself warm than a warm body. First, a word about a process called thermogenesis. One way is by shivering — where the muscles involuntary contract to generate warmth, and defend your body temperature Unlike white fat, which stores heat to keep you warm, brown fat burns calories to generate heat. Both shivering and brown fat activity increase your energy expenditure, causing you to burn more calories in cold temperatures. Now, it is possible to get those energy-burning heating processes going while exercising.
There are three major components to how many calories you burn off in a day: 1 your basal metabolic rate, or the energy used for basic functioning when the body is at rest; 2 the energy used to break down food; and 3 the energy used in physical activity.
0コメント