Brown Fat: Your body’s calorie burning furnace

Most people know that our bodies store fat as supplemental fuel. What most people may not know is there are two types of fat that our body stores: White fat and Brown fat.

White fat is the kind that stores around your midsection, the kind everyone wants to lose come beach season. It serves as an insulating layer that stores energy for future needs.

Brown fat is the kind that burns white fat to produce heat. We have the most brown fat as newborns (hence why newborns do not shiver). As we age, the amount of brown fat in our bodies decreases steadily until adult life when we have just a few storage spots around our neck and upper back, but we don’t utilize it as much.
When we start to get cold, brown fat uses the stored fatty acids in white fat as a source of fuel, giving off tremendous amounts of heat and burning a lot of calories. Hibernating mammals use brown fat as their “winter furnace” and burn their fat stores to stay warm.
Brown fat is like a furnace; it is inactive at comfortable/warm temperatures and turns on once you start to get cold. Brown fat is the main source of body heat production when you are cold. If that is not enough to keep you warm, your muscles start to shiver to produce additional heat (usually below 60 degrees in most people).
Brown fat is most active when your body is cooler, but not to the point of shivering. One study found the most brown fat metabolism occurred during long exposure in healthy males to 66 degree temperatures. The increase in brown fat metabolism carried with it improved insulin sensitivity that could benefit people with type II diabetes or pre-diabetic conditions. It was also associated with an increased metabolism after eating.
How to implement this in your daily life:
Since it is getting colder, it’s easier to get your brown fat active. Simply lowering the temperature of your house/environment a few degrees will increase your brown fat metabolism. Dropping the temp to the 65-67 range would be effective to increase brown fat metabolism significantly, while also lowering your energy bill. If you find yourself shivering, it’s too cold and you could be at risk of hypothermia, so add a layer of clothing. Other options include cooler showers (my least favorite) and exercise/walking in cooler temperatures without added insulating clothing. A few minutes of shivering will not hurt you, but it’s a sign your body is losing heat too rapidly and shouldn’t be ignored.
As your body adapts to the cooler temperatures, you will convert more white fat into brown fat and burn more calories (bigger furnace = more “firewood”). It will take some time, but you’ll find it is easier to stay warm in cooler temperatures without shivering. So if you’ve been storing fat, it’s time to use it to keep warm this winter, not just insulated!