Engaging in regular exercise certainly has an impact on muscle size and fat deposition. Plus, a routine-exercise program gets you feeling and looking fitter more quickly. But only recently have scientists sought to evaluate how training-induced changes in body fat can affect your health.
Some recent findings suggest that exercise doesn’t just shrink the size of fat (known as adipose tissue), but it also stimulates their synthesis of mitochondria-your cell’s energy-producing machinery-which contributes to more efficient fat burning.
This process is what scientists call the “beiging” of white adipose tissue. The body fat actually changes color becoming more beige (or even brown) as more red pigmented-rich mitochondria accumulate within those cells.
In a recent publication in the journal Diabetes, scientists who study the process of beiging of body fat in rodents and humans said that the “profound changes” to white adipose tissue “may be part of the mechanism by which exercise improves whole-body metabolic health” (1).
Exercise Makes Fat Cells More Metabolically Flexible
The scientists noted that the newly-formed beige adipose tissue release special signaling proteins called adipokines which function as hormonal messengers to improve metabolism in skeletal muscle and the liver.
These adipokines can also promote more “metabolic flexibility” within adipose tissue. What this means is that the cells respond more sensitively to insulin and glucose signaling. A more sedentary lifestyle and obesity, on the other hand, is associated with insulin resistance, high blood glucose, thereby fostering a greater potential for developing type 2 diabetes.
A better understanding of the how exercise affects body fat through training-induced adipokines may also help researchers find new targeted therapies for those with insulin resistance or high blood glucose.
Counteracting the Consequences of Overeating
Regular exercise can also counteract some of the metabolic consequences of overeating. For example, eating too much, combined with a sedentary lifestyle, can exacerbate spikes in blood glucose and insulin.
For example, one recent study evaluated the effects of exercise by randomly assigning 26 active young men to either consume 50 percent more energy than normal while severely limiting their physical activity, or to consume the same amount but with added 45 minutes of daily treadmill running (2).
In the group of subjects who overate and didn’t exercise insulin responses increased twofold, which signaled insulin resistance. But in the group that did exercise, the treadmill running appeared to protect against insulin resistance.
In relation to changes in fat tissue, seven of 17 genes related to fat storage were upregulated (increased) in the group that did not exercise. But there weren’t any significant changes to expression of these genes observed in the exercise group. In summary, vigorous-intensity exercise counteracted most of the harmful effects of short-term overeating at the whole-body level, especially in regards to body fat.
Overall, the research highlights why exercise can be good for the body regardless of whether it leads to loss of body weight. Exercise can also bring about metabolic changes that improve not just muscle status but even how body fat color and how it behaves depending on how many mitochondria are concentrated in the adipose tissue. For those regularly training at the gym, it might serve to remember that not only are muscles trained and becoming fitter but body fat is healthier too.
References
- Stanford KI, Middelbeek RJ & Goodyear LJ. Exercise Effects on White Adipose Tissue: Beiging and Metabolic Adaptations. Diabetes. 2015 Jul; 64(7):2361-8
- Walhin JP, Richardson JD, Betts JA & Thompson D. Exercise counteracts the effects of short-term overfeeding and reduced physical activity independent of energy imbalance in healthy young men. J Physiol. 2013 Dec 15; 591(24):6231-43.
