Being carb smart helps keep diabetes at bay, but so does being fat savvy, new research suggests. The key is to stay away from bad fats and embrace the good (unsaturated, vegetable-based) ones. When combined with low carbs, these friendly fats appear to slightly reduce the odds of developing type 2 diabetes.

“Nuts, avocados, olive oil, canola oil, peanuts: all of these have nice effects on lowering risk of type 2,” says study lead author Thomas Halton, PhD. “But high animal fats—in fatty meats, chicken skin, burgers, steaks, and cold cuts—do not.” Halton and his colleagues examined 20 years of dietary survey data from more than 85,000 women. Those who developed type 2 tended to eat more carbohydrates than the other women did. In fact, over two decades, women had a 250 percent higher risk of developing type 2 if they consistently ate foods high in glycemic load, like sugar- sweetened fruit juice, refined sugary cereal, and white bread.

Halton, a Boston nutrition and fitness counselor who conducted the research at the Harvard School of Public Health, speculates that some people resort to these carb-spike foods for an energy boost when they’re trying to cut down on fat. They should instead be swapping one type of fat for another, he says. His research—published in the Feb. 2008 American Journal of Clinical Nutrition—found a protective effect of unsaturated, vegetable-based fats: Women who reported eating the highest amount of these fats were 25 percent less likely to develop type 2 diabetes than women who ate the least.

Previous research by Halton shows that low carbs and the right fats provide similar protection against heart disease. Does this mean people should cut out meat? Not necessarily, says Halton. “Chicken breast and other lean meats are fine, and good sources of protein,” he says.