Can You Turn Your Bad Fat Into Good Fat?
A healthy diet should consist of all three macronutrients – carbohydrate, protein, and fat. Yes, fat. Fat helps provide energy and material for building body tissue including cell membranes and muscle. Fat is also needed to for the body to absorb certain vitamins, such as vitamins A, D, E and K (known as fat-soluble vitamins). Omega-3 fatty acids are good for both the heart and brain.
Just as some fat is good in your foods, the body needs some fat on it as well. While you may strive for a low body fat percentage, your aim is never zero. “Essential” body fat is necessary to maintain life and reproductive functions. The percentage of essential fat for men is lower (2-5%) as women need a slightly higher range due to childbearing and other hormonal functions (goal: 10 to 13%).
You also have fat in the body known as “storage” fat. This fat accumulation protects the internal organs in the chest and abdomen, but as we all know, some is good but too much is bad for our health. Excess body fat can lead to conditions such as heart disease and diabetes.
Our body fat can be broken down even further. Brown fat, known as “good fat” burns calories to generate body heat. Babies, for example, are born with a lot of brown fat so they stay warm. White fat is not considered good fat. This type of fat develops as a result of storing excess calories.
Now, you may think of exercise as a tool toward simply burning away unwanted fat. But researchers have found it can do more than that. It may actually help the body turn our bad white fat into good brown fat. It may also help us boost glucose intolerance and offer us “grace” over a bad diet.
Laurie Goodyear PhD of the Joslin Diabetes Center and colleagues found that active mice show a significant shift in gene expression in subcutaneous fat over sedentary mice. After just 11 days of exercise training, the researchers noted histologic changes known as “browning.” The adipose cells shrank, shedding some of the lipids inside and increased the mitochondria within the cell (which contain pigment that gives a brown appearance.)
Mice with the exercise-trained fat cells also showed improved glucose tolerance even when there was no change to overall body weight or food consumption – even when the mice ate a high fat diet.
Will this same effect occur in human subjects? Dr. Goodyear thinks so. A small study of 10 health men found significant gene expression changes after just 3 months of vigorous exercise (an hour a day, 5 days a week). Although the study did not evaluate the amount of exercise would be needed to achieve the same benefits in diabetic or obese individuals, Dr. Steven Smith MD, of the Sanford-Burnham Medical Research Institute suggests that even just a 10% increase in activity would help.
Kristin Stanford, PhD, a postdoctoral fellow at Joslin Diabetes Center in Boston, said, "Our results showed that exercise doesn't just have beneficial effects on muscle, it also affects fat. It's clear that when fat gets trained, it becomes browner and more metabolically active. We think there are factors being released into the bloodstream from the healthier fat that are working on other tissues."
The study was funded by the National Institute of Diabetes and Digestive and Kidney Diseases and the ADA and presented at the American Diabetes Associations 73rd Scientific Sessions.