Researchers Discover Unexpected Association Between French Fries and Diabetes - Video

A side of fries a few times a week may seem harmless, but new research suggests it could quietly raise the risk of type 2 diabetes over time.

A large study published in The BMJ has found that eating French fries three times a week was associated with a 20 per cent higher risk of developing type 2 diabetes. Surprisingly, the same link was not seen with potatoes prepared in other ways, such as boiling, baking, or mashing, highlighting that how potatoes are cooked may matter as much as the food itself.

Researchers analysed dietary and health data from more than 205,000 adults in the United States over nearly four decades. During the follow-up period, more than 22,000 participants developed type 2 diabetes. After accounting for lifestyle and dietary factors, the team found that every three weekly servings of French fries were linked to a substantially higher diabetes risk, while boiled, baked, or mashed potatoes showed no significant association.

The study also examined what happened when potatoes were replaced with other carbohydrate-rich foods. Swapping three weekly servings of potatoes for whole grains was associated with an 8 per cent lower risk of type 2 diabetes. Replacing French fries specifically with whole grains was linked to an even greater reduction of 19 per cent. In contrast, replacing potatoes with white rice was associated with a higher diabetes risk.

Experts believe French fries may be particularly problematic because they combine rapidly absorbed starch with deep-frying, which increases calorie density and may negatively affect metabolism. Potatoes themselves contain beneficial nutrients such as fibre, vitamin C, and magnesium, suggesting that preparation methods play a crucial role in determining their health impact.

The results reinforce current dietary recommendations that favour whole grains while suggesting that not all potato dishes carry the same health risks. When it comes to diabetes prevention, the choice between fries and whole grains could make a meaningful difference over time.

REFERENCE: Seyed Mohammad Mousavi, Xiao Gu, Fumiaki Imamura, Hala B AlEssa, Orrin Devinsky, Qi Sun, Frank B Hu, JoAnn E Manson, Eric B Rimm, Nita G Forouhi, Walter C Willett. Total and specific potato intake and risk of type 2 diabetes: results from three US cohort studies and a substitution meta-analysis of prospective cohorts. BMJ, 2025;390:e082121 DOI: 10.1136/bmj-2025-082121