New Clue to How Exercise Shrinks Your Belly
- Regular exercise training reduces abdominal fat mass (belly fat)
- A signaling molecule called interleukin-6 plays a critical role in this process
Abdominal fat is associated with an increased risk of not only cardio-metabolic disease, but also cancer, dementia, and all-cause mortality.
Physical activity reduces visceral fat tissue, which surrounds internal organs in the abdominal cavity, but the underlying mechanisms have not been clear.
Wedell-Neergaard and co-senior study author Helga Ellingsgaard of the University of Copenhagen suspected that interleukin-6 could play an important role because:
- It regulates energy metabolism
- Stimulates the breakdown of fats in healthy people
- Is released from skeletal muscle during exercise
As expected, a 12-week intervention consisting of bicycle exercise decreased visceral abdominal fat in obese adults.
But remarkably, this effect was abolished in participants who were also treated with tocilizumab, a drug that blocks interleukin-6 signaling and is currently approved for the treatment of rheumatoid arthritis.
"The take home for the general audience is 'do exercise,'" says first author Anne-Sophie Wedell-Neergaard.
"We all know that exercise promotes better health, and now we also know that regular exercise training reduces abdominal fat mass and thereby potentially also the risk of developing cardio-metabolic diseases."
To test this idea, the researchers carried out a 12-week trial in which they randomly assigned abdominally obese adults to four groups:
- Tocilizumab with exercise routine
- Saline (the placebo) with exercise routine
- Tocilizumab without exercise
- Saline without exercise
Tocilizumab and saline were administered by intravenous infusions every four weeks. The exercise routine was cycling for several 45-minute sessions each week.
In the placebo groups, exercise reduced visceral fat tissue mass by an average of 8 percent, compared with no exercise. But tocilizumab treatment eliminated this effect.
In the exercise groups, tocilizumab also increased visceral fat tissue mass by approximately 278 grams compared with placebo.
In addition, tocilizumab increased total cholesterol and "bad" low-density-lipoprotein (LDL) cholesterol compared with placebo, in both the exercise and no-exercise groups.
"To our knowledge, this is the first study to show that interleukin-6 has a physiological role in regulating visceral fat mass in humans," Wedell-Neergaard says.
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Exercise-Induced Changes in Visceral Adipose Tissue Mass Are Regulated by IL-6 Signaling: A Randomized Controlled Trial. Cell Metabolism.