A new study shows that exposing mice to cold temperatures increases their body’s production of calorie-burning “brown fat” (Molecular Cell, published online Jan. 8, 2015). You have two types of fat in your body:
• white fat that your body stores when you eat too much or exercise too little, and
• brown fat cells, little furnaces that burn white fat for heat and energy.
Excess white fat increases your risk for heart attacks, cancers and premature death. However, brown fat is good for you. By burning extra calories, it helps you to lose weight, get rid of excess fat in your body, and lower high blood sugar levels to help treat and prevent diabetes. Unfortunately, the percentage of brown fat in your body is very small. If you are overweight, the percentage is even lower.
The Experiment in Mice
Exposing mice to cold temperatures increased blood levels of a protein transcription factor called Zfp516 that:
• causes the body to make more brown fat and
• converts white fat cells into cells that can burn some fat.
One group of mice were placed in warm temperatures, while another group was placed in a cold environment. Both groups were placed on a weight-gaining, very high-fat diet. Those living in the cold produced far more Zfp516 and gained 30 percent less weight.
Cold Weather Research in Humans
Studies on outdoor workers in northern Finland who are exposed to cold temperatures show that they have far greater amounts of brown fat compared to people who work indoors. The outdoor workers’ bodies make more brown fat to help keep them warm in the cold weather. Most North Americans avoid cold temperatures as much as they can and spend most of their time indoors with adjusted temperatures. They have very little brown fat and more than 70 percent of the population has more white fat than is healthful.
What Does This Mean for You?
If you are overweight, you are at increased risk for developing diabetes, heart attacks and certain cancers. You are overweight because you eat too much and exercise too little, so you should eat less and exercise more. However, you have already found out that doing this is not so easy. In the winter time, try to get out of your heated house and exercise outdoors. The odds are that you will lose more weight jogging, walking, cycling, dancing, and moving outdoors than indoors.