More than 10% of Americans have diabetes and roughly half of us are at risk for the disease, but most don't know how to eat to prevent the worst outcomes.
To some degree, the advice is the same nutritionists give everybody: eat lots of fruits and vegetables, whole grains, nuts and seeds and avoid heavily processed, packaged foods.
Most people know some features of a healthy diet: eating fruits and vegetables and avoiding soda and fast foods.
But it's more complicated than that. Understanding how diabetes develops can help add to those recommendations and bust some myths.
The first is about weight.
While excess weight increases the risk for diabetes, proper nutrition is likely just as important, said Dr. Dariush Mozaffarian, a cardiologist and professor of nutrition at the Tufts University Friedman School of Nutrition Science and Policy.
"Regardless of your weight, diet has a major impact," he said.
Here is advice from Mozaffarian to help avoid diabetes or keep it under control:
It's not just the glucose
Foods that lead to a spike in blood glucose drive up the amount of insulin released into the bloodstream, which over the long term, increases the risk for diabetes and makes the disease harder to control.
So what is glucose?
►Refined starches, also known as complex carbohydrates, are chains of glucose molecules and have long been known to trigger this rapid spike in blood glucose. These include white rice, white bread and potatoes.
►Added sugar, a simple carbohydrate, is also well known to trigger diabetes because it's 50% glucose.
Fructose, which makes up the other 50%, has almost no effect on blood glucose or insulin – but recent research has shown that it, too, plays a role in diabetes, Mozaffarian said.
Fructose is fine when eaten in low doses in foods that are digested slowly, like fruit. But at high doses, such as in heavily sweetened food or drinks, it triggers the liver to make more fat.
Weight gained from eating fatty foods accumulates under the skin, puffing out cheeks, arms and thighs. But, weight gained from fat produced by the liver is more dangerous, accumulating around the liver and other organs in the abdomen and dramatically increases the risk for diabetes as well as heart disease, Mozaffarian said.
Protein and diabetes
Most Americans get plenty of protein without trying, and there's no need to worry about eating sufficient protein unless you're actively building muscle through activities like weight-lifting, Mozaffarian said.
Too much protein circulates in the bloodstream, raises insulin levels and turns into fat, just like too much starch or sugar does, he said.
Eating extra protein doesn't build muscle alone. So, unless someone is in a meaningful strength training program, they don't need a protein shake or smoothie and should generally avoid excess protein.
Protein in the form of red meat is harmful in another way, Mozaffarian said. The iron that gives red meat its color can damage the pancreas if not eaten in moderation and increase the risk for diabetes.
Diets like paleo and the ketogenic diet are helpful for cutting out refined starches and sugars, Mozaffarian said, but may be harmful long term if they encourage people to eat too much red meat or too much protein.
"There's sort of a sweet spot of getting the right amount," he said.
About 10% of calories should come from protein, he said. The Recommended Dietary Allowance for protein is 0.8 grams of protein per kilogram of body weight. For a 150-pound adult, that’s 55 grams of protein, or 220 calories of a 2,200-calorie diet.
Healthy sources of protein include:
- Nuts and seeds
- Soy
- Beans and lentils
- Poultry
- Fish or seafood
- Eggs
- Yogurt, cheese, or milk
Foods that support a healthy balance of microbes in your gut
Food that promotes a diversity of healthy gut bugs improves metabolism and therefore prevents or helps control diabetes. These foods include:
- Vegetables
- Fruits
- High-fibre foods like beans and whole grains
- Fermented foods, including cheese and yogurt
Too much iron from red meat can throw off the balance of bugs in the gut, leading to diabetes.
And some artificial sweeteners, including aspartame (sold as NutraSweet and Equal), acesulfame potassium (sold as Ace K) and sucralose (Splenda), may increase the risk for diabetes, likely because they throw off the balance of gut microbes.
Veganism and diabetes: What to know
While too much animal protein can promote diabetes, avoiding animal products altogether isn't necessarily the way to go, Mozaffarian said.
"You could have a horrible vegan diet," eating mainly foods like rice cakes and highly processed cereals and breads, which would spike blood glucose and cause the liver to make new fat, he said.
On average, the top two dietary risk factors for developing diabetes are eating too much refined grain and too little whole grain, he said.
While too much red meat is a bad idea, the occasional steak or hamburger won't lead to diabetes.
Don't focus on avoiding fat
People used to think that because they didn't want fat on their bodies, they shouldn't be eating it in their diet. But nutritionists have moved on.
Healthy fats – like those in olive oil, nuts, fish avocadoes and other plant oils – are now considered essential to a balanced diet.
Low-fat diets often replace fat with starch and sugar, which is the worst thing for someone trying to avoid diabetes, Mozaffarian said.
Avoiding fat is "totally the wrong approach," he said.
Exercise can help, but isn't enough on its own
Exercise helps build muscle, and muscle takes up excess glucose and protein in the bloodstream, preventing it from being turned into fat, Mozaffarian said. Someone who is muscular can consume more protein and glucose to maintain a steady state.
Also, although exercise alone doesn't lead to weight loss, it does improve insulin resistance, he said, though it's unclear exactly why.
Eat meals not nutrients
Also, while scientists tend to study single nutrients or foods, most people eat them in combination.
A slice of white bread eaten alone spikes blood sugar and insulin. Dipping that bread in olive oil or spreading it with peanut butter, while adding calories, will also slow down the body’s absorption of the bread's starch, while adding other beneficial nutrients.
That may be why ice cream, which has dairy as well as sugar, has not been linked to a higher risk of diabetes, Mozaffarian said.
Bottom line
Diabetes may be a disease of insulin resistance and abnormal glucose metabolism – but it's also about protein and fat metabolism, Mozaffarian said.
"All the nutrients are thrown out of whack when you have diabetes," he said.
There's no question it's better to avoid diabetes. Diabetes increases the risk of infection, cancer, blindness, kidney disease and heart disease, among other health problems.
"It's really a systemic disease," Mozaffarian said.
Contact Karen Weintraub at kweintraub@usatoday.com.
Health and patient safety coverage at USA TODAY is made possible in part by a grant from the Masimo Foundation for Ethics, Innovation and Competition in Healthcare. The Masimo Foundation does not provide editorial input.
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