Your thermostat may be another tool in your weight-loss arsenal. The human body undergoes a few key physiological processes when the thermometer drops: your metabolism goes up and your body starts eating into your fat stores as the rate of calories burned increases.
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Some studies even suggest that simply spending time in cold environments produces a better caloric burn than exercise — though precisely how many isn't known.
Cold Prevention Includes Calorie-Burning Shivers
There are three stages to cold prevention the human body employs to stay warm, says Dr. Francesco Celi, chair of the Division of Endocrinology and Metabolism at the Virginia Commonwealth University School of Medicine.
First, your body undergoes vasoconstriction, moving blood from your extremities to maintain temperature in your core. If the temperature drops further, your body undergoes non-shivering thermogenesis, in which your body starts burning through brown fat to generate heat. As a last resort, you begin to shiver, an inefficient but highly effective method for generating heat that also happens to burn a lot of calories.
Read more: Is Running in Cold Weather Good or Bad?
Burning Calories While Cold
The amount of calories burned in the cold depends on your body type, your diet, the temperature and even the clothes you're wearing. One study conducted by the U.S. National Institutes of Health showed that just 15 minutes spent in the cold can be the metabolic equivalent of a full hour of exercise.
Shivering burns up to five times more energy than a body at rest, and even mild cold that doesn't cause you to shiver starts to burn through those brown fat stores, jumpstarting your caloric burn rate.
The Secret of Brown Fat
Brown fat is a beneficial fat, unlike the white fat cells that make up the extra weight around your waistline. The presence of brown fat cells may be partially genetic, and the role of brown fat cells isn't totally understood, but Celi's clinical experiments showed a link between cold exposure and the production of brown fat from white fat cells.
The mechanism, a hormone called irisin, is also responsible for nonshivering thermogenesis, allowing you to burn through calories in the form of brown fat at lower temperatures. You don't need to shiver to see a benefit from the cold.
Maximizing Your Caloric Burn
Celi does state that the calorie-burning effects of cold temperatures aren't additive, so conducting your workout in your backyard on a cold morning won't double your calorie-burning; however, the dramatic effects of cold exposure might encourage you to turn the thermostat down in your house. Calorie burning is never worth risking hypothermia or exposure, but a little discomfort could go a long way towards achieving your weight-loss goal.