June 22, 2023 – Genetics or lifestyle -- which matters more?
It’s one of those eternal questions in health care, but new science has an answer: Lifestyle matters more, at least when it comes to preventing type 2 diabetes.
Among 60,000 healthy, middle-aged adults, those who exercised the most – at least 68 minutes a day – were 74% less likely to have type 2 diabetes after 7 years than the least active people (those logging less than 5 minutes of exercise a day).
This was true even for those with a high “genetic risk score” – those who were 2.4 times more likely to get the disease due to their genes.
But here’s the really striking finding: People with a high genetic risk who were the most active had a lower risk of getting type 2 diabetes than sedentary folks with no genetic risk.
This highlights how powerful exercise can be for preventing chronic disease, said Melody Ding, PhD, senior author of the study, which was published this month in the British Journal of Sports Medicine.
"The take-home message is that doing something is better than doing nothing, and doing more is even better,” said Ding, an associate professor of public health at the University of Sydney, in Australia. “If it's within your capacity, increase your activity to at least a moderate degree."
Exercise Is Good, More Exercise Is Better
Exercise is already a front-line strategy for preventing and managing type 2 diabetes. But little is known about how well exercise can offset genetic risk, the researchers say.
And while most studies rely on self-reporting, this one used fitness trackers to monitor the amount and intensity of physical activity, the researchers say. In theory, that means they could more reliably pinpoint what “dose” of exercise is best for stopping diabetes.
But according to the study, any amount of physical activity – even 5 to 25 minutes a day – can help lower diabetes risk if the activity is done at a moderate to vigorous intensity.
The basic mechanism is well established, Ding said. When your muscles work, they burn glucose (sugar) for fuel, clearing it from your bloodstream and lowering blood sugar as a result. Exercise also makes your body more sensitive to insulin, she said.
But recent research also shows that endurance exercise like cycling and running can improve the way genes function, particularly genes related to metabolic health.
"As genes adapt to the stimuli they're given through exercise, they function in slightly different ways," said Mark Chapman, PhD, an assistant professor of integrated engineering at the University of San Diego, and the lead author of a study on this topic.
For example, genes might deliver more oxygen to your muscles or learn to regulate your blood sugar more efficiently, he said. Over decades, these gene adaptations could help prevent diabetes and other metabolic diseases. Still, "even a month of training can make a difference," Chapman said.
How Do You Know if You’re Working Out Hard Enough?
For diabetes prevention, moderate to vigorous activity was key, the study showed.
Moderate activity means you’re breathing a little harder and probably breaking a light sweat. A brisk walk, a bike ride on level ground, or even gardening and house chores will do, as long as you’re working a bit harder or moving a bit faster.
Vigorous activity is harder still. You’re breathing hard and fast, working up a good sweat, and struggling to say more than a few words without pausing for breath. Think jogging, cycling up hills, or moving a couch up a flight of stairs.
And don’t forget strength training. A research review in Sports Medicine found that people with a high genetic risk for diabetes saw big improvements in body fat, blood lipids, and glycemic control after 12 weeks of strength training at a moderate intensity.
If you have a family history of diabetes, you can use that as motivation. That’s what Ding does. Several family members on her father's side have type 2 diabetes, and knowing that keeps her going. She does cycling, swimming, high-intensity interval training, strength training, dance, and yoga.
"Moving more, with at least moderate intensity so you're a little out of breath and sweating a bit, is a big part of counteracting genetic susceptibility," she said.
