- A new study from Harvard T.H. Chan School of Public Health found that eating french fries three times a week or more is associated with a 20% increased risk of developing type 2 diabetes.
- Other preparations of potato did not yield the same degree of risk, indicating that it’s the cooking method that’s the primary culprit.
- Nutritional guidelines and a dietitian emphasize that potatoes can still provide valuable nutrition, including fiber, potassium, and vitamin C.
Whether you love them baked, mashed, roasted, grilled, or stuffed, potatoes are popular all across America — and the world. But if you love your spuds in fry form, you might want to pause before firing up the deep fryer or placing that next fast-food fry order, because researchers at Harvard T.H. Chan School of Public Health just uncovered some potential health implications from this popular dish.
The new study, published this week in The British Medical Journal, found that eating french fries three times a week was associated with a 20% increased risk of developing type 2 diabetes when compared to eating them less than once a week. This is a valuable insight considering that about 1.2 million Americans are diagnosed with diabetes every year, according to the American Diabetes Association.
The Harvard team analyzed data from four decades of 205,107 adults in the United States who didn’t have diabetes, cardiovascular disease, or cancer when the study began. The takeaway? The risk for developing type 2 diabetes wasn’t the potato’s fault on its own. Instead, it came down to how this humble ingredient was prepared, with deep-fried potatoes yielding the worst results.
Is it still okay to include potatoes in your diet?
Potatoes are considered a vegetable and can be included in a healthy eating plan, according to the United States Department of Agriculture’s (USDA) and Department of Health and Human Services’ (HHS) 2020–2025 Dietary Guidelines for Americans.
“Potatoes are a staple in many cultural diets across the globe and can absolutely be considered a ‘healthy’ addition to the diet,” says registered dietitian and certified personal trainer Elizabeth Shaw, MS, RDN, CPT, an author and nutrition communications strategist.
Potatoes are naturally fat-free and sodium-free, in addition to containing fiber, protein, and other key vitamins and minerals. For reference, one medium cooked potato with the skin on contains 118 calories, 0.1 grams of fat, 27 grams of carbohydrates, 2.5 grams of dietary fiber, and 2.5 grams of protein. It also provides 515 milligrams of potassium and is a source of vitamin C.
Can the way you cook potatoes really change how they affect your body?
According to researchers, yes. This study found no significant diabetes risk associated with potato preparations such as baked, boiled, and mashed tubers or even potato chips. The only culprit? French fries.
French fries are typically deep-fried in oil, heavily salted, and in some cases made with added flours, sugars, or preservatives. Take McDonald’s famous fries, for example. In addition to potatoes and vegetable oil, they include beef flavoring, dextrose (a simple sugar), sodium acid pyrophosphate (an additive), and salt. One large order packs in 480 calories, 23 grams of fat, and 400 milligrams of sodium.
What is the most nutritious way to cook a potato?
To start, keeping the skin on potatoes for serving is an excellent choice because this is where you’ll find the most fiber. “Increasing dietary fiber has been linked to improved health outcomes, including better blood sugar control, weight management, and more,” explains Shaw.
She adds that the cooking method matters too, saying, “It’s best to consider the cooking method if they’re a daily part of your diet, opting for boiled, baked, air-fried, or roasted over deep-fried options.”
So what should a fry lover do? Shaw recommends making homemade fries and cooking them in an air fryer. “Slicing them into steak-size fries with a spritz of olive oil and salt yields that same restaurant-quality texture and taste without the fat and calories of a traditional french fry,” she notes.
Mashed potato or baked potato fans can also make a few smart swaps if desired. Instead of opting for a pat of butter or using full-fat sour cream and cheese, try mixing in Greek yogurt or light sour cream for that same creamy taste with less saturated fat.
How much is too much potato?
“A medium potato, or about 5 ounces, is the standard serving size… Think about the size of a small fist,” advises Shaw. How often you enjoy potatoes will depend on your individual nutritional needs and health goals.
“Personally, I recommend variety in my clients’ diets, encouraging them to alternate between russets, sweet, and red potatoes to get their potato fix in while providing their body with a variety of nutrients,” she suggests.
If you enjoy potatoes daily, that’s okay too. “It really depends on how you’re enjoying them (like baked over fried) and alongside what other nutrient-dense foods.” Shaw recommends pairing potatoes with healthy fats and protein to help support balanced blood sugar levels.
What it boils down to is that there’s no need to shun potatoes from your kitchen. Just pay attention to preparation methods, limiting deep-fried french fries and opting for air-fried, boiled, baked, roasted, or mashed potatoes when possible.
And as always, if you’re concerned about whether or not potatoes are a good addition to your diet — and especially if you’re concerned about diabetes — it’s best to talk with a health professional who can ensure your nutrition meets your personal needs.
