Diabetes and Diet: How Do Weight and Exercise Affect Your Risk of Diabetes?

The good news about diabetes: it’s not inevitable.

“Up to 90 percent of type 2 diabetes is preventable by lifestyle modification,” says JoAnn Manson, director of preventive medicine at Brigham and Women’s Hospital in Boston.


“If you can stay within a healthy weight, you’re about halfway there. Once you add exercise, you’re down to about a 70 percent lower risk compared to people who are overweight and not engaging in regular exercise.”

Those figures come from a study that tracked tens of thousands of healthy people for 16 years.

Even stronger evidence comes from the Diabetes Prevention Program study, which randomly assigned roughly 3,800 people with prediabetes to metformin (a drug that lowers blood sugar), typical diabetes education, or an “intensive lifestyle intervention” to exercise and cut calories (especially from fat).

“The Diabetes Prevention Program found close to a 50 percent reduction in the progression to diabetes with very modest weight loss,” says Manson, who is also a professor of medicine at Harvard Medical School. The average participant lost about 12 pounds. (The metformin takers had a 30 percent lower risk.)

“They ate a lower-calorie, generally healthier diet and exercised about 30 minutes a day,” notes Manson. “The reduction in risk you get just from weight control and regular physical activity is enormous, and it’s true for all ethnicities, races, and age groups.”

That also applies to people who have diabetes. “In the Look AHEAD study, we found that some people in the weight loss intervention could reverse their diabetes,” says the CDC’s Edward Gregg.

“Among the group whose weight loss was on average 8 percent that first year, 11 percent had at least a partial remission. They were going off their medications and their levels of blood sugar were below the diabetic threshold.”

Does what—not just how much—you eat also make a difference in your risk of diabetes? Yes, says Manson, “but consuming more calories than you’re burning is by far the stronger risk factor.”

Sources: N. Engl. J. Med. 345: 790, 2001; N. Engl. J. Med. 346: 393, 2002; JAMA 308: 2489, 2012.

2 Replies to “Diabetes and Diet: How Do Weight and Exercise Affect Your Risk of Diabetes?”

  1. Most of these type of studies compare people eating the standard American diet who then switch to a more healthy diet. What if you are already exercising, eating a very healthy diet, and tracking calories, but still have higher blood sugar than you would like? That is my situation and it is rarely if ever addressed in studies or articles such as this.

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