Just by increasing their physical activity, people with type 2 diabetes can lose fat that accumulates in the liver and abdomen and lower their risk of heart problems.
Doctors recommend that people diagnosed with diabetes get regular exercise, since physical activity can keep them at a healthy weight and help organs like the lungs, liver and heart to work at their best. But the details of how breaking a sweat influences the different fat deposits around the body are not so clear.
There is increasing evidence, for example, that buildup of fat in the abdomen and deep in organs such as the liver and heart, can be more harmful than fat deposited just under the skin, since the more deeply embedded fat, known as visceral fat, releases hormones and other compounds that can affect how efficiently the body breaks down calories. But because most studies involving exercise also allow volunteers to change their diet, pinpointing how physical activity changes fat depots in the body has been hard to document.
To gather more information on this relationship, researchers from Leiden University Medical Center in the Netherlands turned to detailed MRI images to study 12 middle-aged diabetic patients both before and after they participated in a six month program of moderate-intensity exercise. The volunteers exercised for 3.5 hours to 6 hours a week, and participated in two endurance and two resistance training sessions, finishing up with a 12-day hiking expedition. Throughout the study, however, they were told not to change their diet and eating habits. After the training, the researchers found that the participants’ heart functions remained relatively unchanged, but the second round of MRI scans revealed significant decreases in the volume of fat that surrounded the heart and lungs as well as in their abdominal area.
In a statement, the study’s senior author, Dr. Hildo J. Lamb from the Department of Radiology at Leiden University Medical Center said, “The liver plays a central role in regulating total body fat distribution. Therefore, reduction of liver fat content and visceral fat volume by physical exercise are very important to reverse the adverse effects of lipid accumulation elsewhere, such as the heart and arterial vessel wall.”
Because the study did not follow the patients for an extended period of time, the changes in fat distribution did not translate into measurable changes in heart function, but the researchers hope that with additional follow up, that would occur. And while the study was small, the results were encouraging since the participants were able to lower their levels of harmful fat simply by becoming more physically active — without changing their diet.
The findings also give researchers new insight into how different types of fat in the body contribute to diseases such as diabetes and heart disease. Imaging techniques like MRI, for example, might one day identify people at greater risk of developing the insulin resistance that heralds diabetes, or future heart problems by revealing fat depots wrapped around organs. That in turn could help more people to address their risk factors and prevent health problems by exercising more, or changing their diet, or both.
The study is published in the journal Radiology.
June 25, 2013
By Alexandra Sifferlin, photo by Joel Carillet / Gett Images