Eating a lot of grilled, baked, or fried foods may raise your risk for diabetes, according to a new study. These dry-cooking methods produce compounds that cause harmful inflammation and cell damage in the body, say researchers, which can lead to increased insulin resistance—a condition that can then lead to full-blown diabetes.
This advice may sound surprising, considering that grilling and baking are often considered healthy (not to mention, quick and easy) cooking techniques. And it’s true that they do tend to be lower-calorie and lower-fat options than, say, frying or cooking in oil.
But these methods may not be best for people at increased risk of type 2 diabetes, says study co-author Jaime Uribarri, MD, a professor at the Icahn School of Medicine at Mount Sinai in New York City. Research has shown that when the sugars in foods—especially animal-based foods, such as meat and dairy products—are cooked with high, dry heat, they produce harmful inflammatory compounds known as advanced glycation endproducts (AGEs).
To see how AGEs might affect insulin resistance, Dr. Uribarri and his colleagues studied two groups of obese volunteers, all of whom had metabolic syndrome—a cluster of conditions like high blood pressure and insulin resistance that raise a person's risk of diabetes and heart disease. One group ate a typical Western diet, which tends to be high in AGEs, while the other was instructed to follow a low-AGE diet. (The latter was instructed to avoid grilling, frying, or baking their food, and to poach, stew, or steam it instead.)
The researchers took blood and urine samples at the beginning and the end of the one-year trial, and found that markers of insulin resistance, inflammation, and oxidative stress worsened over time in the regular diet group but improved in the low-AGE group. People in the low-AGE group also lost slightly more weight, on average, than the regular-diet group.
The findings suggest that elevated levels of AGEs can be used to diagnose and treat obese patients who are at risk for diabetes, says Dr. Uribarri. "A reduced-AGE diet can help prevent diabetes in these patients, even without changing caloric, fat, or carbohydrate content of the food," he says. Since weight loss can be difficult for obese people, the study authors point out, reducing AGEs may offer an alternative approach to lowering diabetes risk in this group.
There are a few simple rules for following a low-AGE diet, says Dr. Uribarri: “Try to apply less heat that usual, use plenty of water, and increase the cooking time,” he says. Using acid-based marinades, like vinegar or lemon juice, also tends to decrease the formation of AGEs.
AGEs are not the same as acrylamide—a chemical compound formed when meat is charred or blackened, which has been shown to contribute to cancer growth. But they are related, says Dr. Uribarri. “It follows the same principle that both are created when you overdo the cooking,” he says. “You can avoid both in the same ways.”
The study, published in the journal Diabetologia, is a follow-up to a 2014 Mount Sinai study that found that high levels of AGEs in the body can also cause brain changes similar to Alzheimer’s disease.
Of course, switching from grilled steak to beef stew won’t make a huge difference in your inflammation levels or overall diabetes risk if the rest of your diet and lifestyle is unhealthy. “There is clearly a benefit to modifying the way you cook,” says Dr. Uribarri. “But it doesn’t mean you can forget about everything else and continue to eat a lot of carbohydrates or high-fructose corn syrup.”
The best advice, he says, hasn’t changed much: “Stick with a healthy diet, try to avoid sodium and processed foods, and then pay attention to the way you cook.”