Regulating body temperature in cold weather is a natural process of producing heat known as thermogenesis. There are methods of raising body temperature through shivering and non-shivering thermogenesis activities. Shivering produces heat with contracting muscles causing some of the energy to show up as heat. Non-shivering thermogenesis occurs in brown adipose tissue found in mammals. This type of heat production is a result of neurotransmitters activating brown fat cells to release hormones and proteins causing cellular metabolic rate elevations.
As mammals, we have the ability to store fat as insulation and as an energy reserve. Our bodies have several types of fat known as adipose tissue. White adipose tissue (WAT) or white fat is what we consider as body fat. It is primarily used as a store of energy and can actually burn a few calories per pound a day. Brown adipose tissue (BAT) or brown fat has the job of burning calories and white fat. BAT is composed of more capillaries than white fat and acts more like muscle tissue, which also burns energy.
This brown fat is the key to losing weight in winter as it is activated by cold weather. The ability to create heat comes from it's reddish-brown color due to it's power producers inside the cell called mitochondria, which give cells energy by turning calories into heat.
A Harvard Medical School study (http://www.health.harvard.edu/staying-healthy/major-fat-burning-discovery) has shown there is a powerful effect from brown fat cells as they release the “exercise hormone” called irisin that boosts their calorie-burning ability. Body movement or exercise whether light, moderate or vigorous, prompts the irisin to activate genes and protein that transform calorie-storing white fat cells into brown fat cells. The brown fat cells even continue to burn energy after exercise is finished. Irisin also appears to restrain the formation of other fatty adipose tissue.
Now we know about thermogenesis with relation to brown fat and it’s ability to burn calories. But, how can we increase this fat killing powerhouse to burn more calories?
No more, no less, just the right amount. Hunger-regulating neurons in the brain can help encourage white fat to turn brown. This is achieved when eating just the right amount of food to satisfy hunger. Eating too few calories prevent white fat from turning brown. Overeating creates more white fat and interferes with brown fat’s ability to burn calories.
An apple (peel) a day. Apples have high concentrations of ursolic acid in their peels, which increases brown fat and muscle mass. Other foods containing ursolic acid include blueberries, cranberries, plums and herbs like rosemary, oregano, mint leaves and thyme.
Get moving. Exercise obviously burns calories, but also increases metabolism, releases the “exercise hormone” irisin, and converts white fat into brown fat. Staying active inhibits the formation of fatty tissue and regulates glucose and insulin levels all while increasing healthy brown fat overall.
Turn down the heat. There is a fat-burning benefit to colder weather as it causes our body to shiver and activates reactions intrinsically within brown fat cells. As we are mammals and use fat cells to store energy, our bodies are designed to eventually utilize that fuel to regulate our core body temperature in cold temps. Therefore, we produce heat on our own through thermogenesis, which burns calories, turns white fat into brown, and results in decreasing body weight.
Our bodies are efficient energy-producing machines equipped with ancient biological survival mechanisms. This gives us the advantage to produce heat and subsequently help our bodies not only survive winter weather, but also lose fat and maintain a healthy weight.