(Photo by Towfiqu Barbhuiya on Unsplash)
ANN ARBOR, Mich. — Is it really possible to make your fat healthier? In a groundbreaking study, researchers at the University of Michigan have uncovered some surprising benefits of long-term exercise for people with obesity. It turns out that being a dedicated gym-goer might be doing more for your body than just burning calories – it could be changing the very nature of your fat tissue.
We often think of fat as the enemy, but it’s actually an essential part of our bodies. Fat tissue, also known as adipose tissue, helps us store energy, keeps us warm, and even produces hormones. However, not all fat is created equal.
The fat just under our skin, called subcutaneous fat, is generally considered healthier than the fat that accumulates around our organs (visceral fat) or within the organs themselves. This study, published in the journal Nature Metabolism, focused on subcutaneous fat in the belly area.
The research team, led by Jeffrey Horowitz, a professor of movement science at the University of Michigan’s School of Kinesiology, compared two groups of adults with obesity, including 16 people who exercised regularly (at least four times a week) for an average of 11 years and 16 people who had never exercised regularly.
The researchers took samples of subcutaneous fat tissue from both groups and examined them closely.
What they found was fascinating. The fat tissue from the long-term exercisers showed several distinct characteristics:
- More blood vessels
- More mitochondria (the powerhouses of cells)
- More beneficial proteins
- Less of a type of collagen that can interfere with metabolism
- Fewer cells that cause inflammation
In essence, the exercisers’ fat tissue was structurally and biologically different from that of the non-exercisers. So, what does this mean for our health?
Why These Differences Matter
“Our findings indicate that in addition to being a means to expend calories, exercising regularly for several months to years seems to modify your fat tissue in ways that allows you to store your body fat more healthfully if or when you do experience some weight gain––as nearly everyone does as we get older,” Prof. Horowitz explains in a media release.
In other words, long-term exercise appears to increase the capacity of subcutaneous fat tissue to store fat effectively. This is important because it means that if you do gain weight, your body is more likely to store that extra fat in the healthier subcutaneous tissue rather than in more dangerous areas like around your organs or inside your liver.
To further investigate these differences, the research team did something quite innovative – they grew fat tissue in the lab using cells collected from both the exercisers and non-exercisers. Remarkably, the cells from the exercisers developed into tissue that was better at storing fat.
You might be wondering why having fat tissue that’s better at storing fat is a good thing. Isn’t the goal to have less fat? Well, it’s not that simple.
As we age, most of us tend to gain some weight. If that weight gain is inevitable, it’s far better for our health if the extra fat is stored in subcutaneous tissue rather than accumulating around our organs or within organs like the liver.
In fact, one growing health concern in the U.S. and elsewhere is nonalcoholic fatty liver disease, which occurs when excess fat builds up in the liver. This condition is most common in people with overweight or obesity and can lead to serious health problems like cirrhosis or liver cancer.
It’s important to note that having fat tissue that’s better at storing fat doesn’t mean you’ll automatically gain weight.
“What it means is that if or when people experience weight gain, this excess fat will be stored more ‘healthfully’ in this area under the skin, rather than in the fat tissue around their organs (visceral fat) or an accumulation of fat in organs themselves, like the liver or heart,” Prof. Horowitz points out.
This study opens up exciting new avenues for research. The team plans to conduct long-term studies tracking people as they start and maintain exercise programs over several years. They’re also interested in exploring whether certain types or intensities of exercise might be more effective at modifying fat tissue.
Additionally, they want to investigate whether the lab-grown fat tissue from exercisers and non-exercisers functions differently, and if there are other health-related differences that could impact both the tissue and the person it came from.
Paper Summary
Methodology
This study compared two groups of adults with overweight or obesity: one group of regular exercisers who had been participating in endurance-type exercise for over two years and another group of sedentary non-exercisers. The researchers examined abdominal subcutaneous adipose tissue (aSAT), the fat stored just under the skin, to see if long-term endurance exercise made a difference in its structure and function.
Participants were carefully matched by age, sex, and body fat percentage to ensure fair comparisons. The team used advanced laboratory techniques to analyze fat samples, looking for differences in things like blood vessel density, protein levels, and fat-storing capacity. Additionally, exploratory experiments were done with tissue samples grown outside the body to observe how they behaved in a controlled environment.
Key Results
The researchers found that the exercisers had healthier fat tissue than the sedentary group. The fat tissue from the exercisers had more blood vessels, which helps supply oxygen and nutrients to the cells. They also had fewer harmful inflammatory cells, and their fat was better at storing and managing lipids (fat molecules). The tissue from exercisers had more proteins that help burn fat and produce energy. Overall, regular exercise seems to make fat tissue healthier by improving how it stores fat and fights inflammation, even if people have the same body fat percentage.
Study Limitations
One limitation of the study is that it was cross-sectional, meaning it looked at the differences between two groups at one point in time. This design does not allow researchers to see how changes in exercise habits over time might affect fat tissue. Another limitation is that the study participants self-reported their physical activity levels, which could lead to inaccuracies. The exploratory experiments done on tissue outside the body may not perfectly reflect what happens inside the body. Finally, the study only included people with overweight or obesity, so the findings may not apply to people with a healthy weight.
Discussion & Takeaways
This study highlights the positive effects of long-term endurance exercise on fat tissue. The exercisers had healthier fat that could better store lipids and support overall metabolic health. These changes in the fat tissue may help protect against obesity-related diseases like diabetes and heart disease. The findings suggest that regular exercise, even without weight loss, can improve the health of fat tissue and possibly contribute to better overall health. The study emphasizes the importance of staying physically active, regardless of body size, to improve how fat tissue functions and reduce the risk of metabolic diseases.
Funding & Disclosures
This study was conducted by researchers from the University of Michigan. The research was funded by several institutions, including the School of Kinesiology and the Department of Biostatistics at the University of Michigan. The authors disclosed no conflicts of interest related to this study, ensuring the results are unbiased and objective.
