Exercise can play a critical role in reducing weight, but the pounds seem to come off more easily for some people than others. A new study that highlights subtle differences in a class of molecule involved in metabolism could help explain why.
The molecule in question is a protein involved in the breakdown of carbohydrates and fats called PGC-1⍺. While it has previously been linked to exercise and weight, the mechanisms and processes at play haven't been clear.
In this new research, a team of experts from across Japan discovered that multiple variants of PGC-1⍺ are actually involved, and that it is in fact these PGC-1αb and PGC-1αc variants that can really make a difference to exercise and weight loss.
Kobe University biomedical scientist Kazuhiro Nomura and team found that if the mouse's bodies increase the expression of PGC-1αb and PGC-1αc variants in response to exercise, they signal the rest of their bodies to increase energy output.
The team ran tests on mice and 10 male human subjects – on treadmills and exercise bikes, respectively – then took small tissue samples to figure out what was happening in terms of muscle metabolism, fat burning, and oxygen consumption.
To test production of PGC-1α specifically, some mice were bred without the PGC-1αb and PGC-1αc proteins. The mice without the proteins in question ended up becoming obese and having too much insulin in their blood.
For the human test, men classed as insulin intolerant – a condition known to reduce PGC-1α levels – were included in the group. The researchers found that levels of PGC-1αb and PGC-1αc were both boosted by exercise, which in turn led to the body's metabolism working more efficiently.
These findings suggest that our ability to produce PGC-1αb and PGC-1αc is somehow linked with how easy we find it to keep the weight off, a discovery that the scientists were expecting based on earlier studies.
"The hypothesis that the genes in skeletal muscle determine susceptibility to obesity was correct," says endocrinologist Ogawa Wataru, from Kobe University in Japan.
As with any brand new discovery the consequences of the findings aren't fully clear, requiring future research study these processes in larger and more diverse groups of people.
However, this does give us another clue as to why the exercise-to-weight-loss ratio isn't the same for everyone. No doubt a multitude of factors are involved, but if the activity of PGC-1αb and PGC-1αc can be artificially managed further down the line, it's possible that a whole new variety of weight loss treatments could appear.
"If a substance that increases the b and c versions can be found, this could lead to the development of drugs that enhance energy expenditure during exercise or even without exercise," says Ogawa.
"Such drugs could potentially treat obesity independently of dietary restrictions."
The research has been published in Molecular Metabolism.