Are Potatoes Healthy? Not in the Form of French Fries, Diabetes Study Shows

Should you eat white potatoes if you’re worried about diabetes? The starchy tuber’s high carbohydrate content and elevated glycemic index (a measurement of how quickly a food raises blood sugar) has given it a bad reputation among people conscious of their glucose levels.

But a new study finds that the issue might not lie with the potato itself, but with how you cook it and what you eat instead.

Are Potatoes Healthy? It Depends on How You Prepare Them

For this research, investigators followed more than 200,000 men and women enrolled in the Nurses’ Health Study, Nurses’ Health Study II, and Health Professionals Follow-up Study. For more than 30 years, the participants regularly responded to dietary questionnaires, detailing how often they ate certain foods, including whole grains and all manner of potatoes.

They also reported on various other health and lifestyle factors that researchers controlled for, such as how often they exercised and how much alcohol they drank.

Key findings from the study included:

• Over the course of the study period, more than 20,000 participants developed type 2 diabetes.
• 3 servings of french fries a week increased the risk of developing diabetes by 20 percent.
• Baked, boiled, or mashed potatoes didn’t significantly impact the risk of type 2 diabetes.

Why Frying Potatoes Increases Type 2 Diabetes Risk

French fries are usually deep-fried at very high temperatures, often in oils, says Dr. Mousavi. During many of the years when the data was collected, that oil may have contained trans fats and other harmful compounds, he says.

“This combination can lead to inflammation, damage blood vessels, and raise blood sugar levels. On top of that, potatoes themselves have a high glycemic load, meaning they can spike blood sugar quickly, especially when fried and salted,” says Mousavi.

This research has limitations. As an observational study, it showed a link, but couldn’t prove that fries caused the increased risk. “While french fries could be what’s making it more likely that people develop type 2 diabetes, it could also be something else eaten with the french fries or other behavior linked to the french fries,” says Susan Spratt, MD, a professor of medicine and a diabetes and metabolism expert at Duke Health in Durham, North Carolina. Dr. Spratt was not involved in the study.

Replacement of Fries With Whole Grains Could Slash Diabetes Risk

Using information gathered from the studies, the researchers determined that those who ate whole grains instead of french fries lowered their diabetes risk by 19 percent. The choice of whole grains over baked, boiled, or mashed potatoes reduced the risk 4 percent.

The study also found that forgoing baked, boiled, or mashed potatoes in favor of refined grains like white rice actually increased the risk of type 2 diabetes, highlighting the importance of choosing whole grains over refined carbohydrates.

“It’s not just about cutting back on fries — it’s about making smarter, healthier swaps,” says Mousavi.

What’s Healthier Than a Side of Fries?

If you say no to fries with your fast food meal, what can you order instead? Unfortunately, tater tots or chips are still fried potatoes, so those aren’t great options, says Margaret O’Brien, RD, a registered dietitian at Banner Health in Phoenix, Arizona.

“Look at substituting a side salad or other vegetables, coleslaw, or fruit,” says O’Brien, who wasn’t involved in the study.

If there’s no healthy alternative, Spratt suggests skipping the fries and just eating the burger or chicken sandwich. “And don’t forget that walking just a few minutes after a meal can help your body metabolize your food,” she says.

You Don’t Have to Give Up French Fries Entirely

You don’t have to give up fries completely to keep your risk of type 2 diabetes in check, says Mousavi.

“Cutting back makes a difference — going from three servings to one per week could help lower your risk,” he says.

Fries made at home in the oven or air fryer with a bit of healthy oil are likely a much better option than fast-food fries. “The goal isn’t perfection — it’s making small, smarter swaps,” Mousavi says.