Do French fries really increase type 2 diabetes risk? The truth behind the headlines.

Summary

• The study examined the association—not causation—between consuming different amounts and types of potatoes and type 2 diabetes.
• There was no association between French fry consumption and type 2 diabetes risk after 2010.
• There was no association between the consumption of baked, boiled, or mashed potatoes and type 2 diabetes risk.
• Prior to 2010, the greatest association between French fry consumption and type 2 diabetes was only found with serving sizes ten times larger than what the average American eats in a week.

A recent study in The British Medical Journal (BMJ) made headlines with the claim that eating fried potatoes may raise the risk of type 2 diabetes. But before you swear off French fries altogether, it’s worth taking a closer look at what the research actually shows.

Association Does Not Equal Causation

As an observational study, the BMJ study’s results can only show an association, not cause and effect. This means the researchers cannot definitively say that eating a certain amount of fries is the reason, or even a reason, for a person’s risk of type 2 diabetes increasing.

No Significant Risk Associated with Fries After 2010

Another critical point: While the data used in the study goes back to 1986, when analyzing data from 2010 forward, there was no significant risk of diabetes for people eating three servings of fries per week. The study authors did not explain this finding, but the timeframe aligns with the removal of trans fats from the food supply.

Trans fats are associated with a higher risk of type 2 diabetes. State and local governments in the United States began efforts to limit trans fats in the early 2000s and called for their removal from the food supply by 2015. The food industry took the initiative to reformulate products to phase out trans fats – many well before the 2015 deadline – and fried potatoes had already ceased to be a source of trans fats. In fact, a 2015 study published in the journal Advances in Nutrition found that “French fried potatoes are no longer a source of trans fatty acids in the food supply.”

Serving Size Matters

The serving sizes used in the study also don’t reflect real-life eating habits. For example, the average person eats a little less than half a cup of fries per week (about 60 g) [1]; the serving size used in the paper is about twice that.

The greatest increase in type 2 diabetes risk cited by the study (27%) was associated with very high consumption of fries – five or more servings per week (566-859 g). That’s about 10 times more fries than the average person eats.

No Significant Risk of Diabetes Associated with Non-Fried Potatoes

Notably, the study found no association between eating any amount of baked, boiled, or mashed potatoes and risk of type 2 diabetes. Put another way, this is evidence that potatoes themselves show no association with type 2 diabetes risk.

Study Limitations

The study researchers themselves highlighted a few limitations with the study:

• Other lifestyle or diet-related factors could be influencing the results, making it hard to know if there is an actual correlation between high intakes of fried potatoes and type 2 diabetes risk.
• The results might not apply well to the general public, since most participants were health professionals, and about 90% were of European descent.

Nutrient-Dense Potatoes Provide Nutrients to Fuel the Body and Brain

Nutrient-dense potatoes are America’s favorite vegetable, and for good reason. A medium, skin-on potato delivers more potassium than a medium-sized banana, about one-third of the daily recommendation of vitamin C, and 3 grams of plant protein. With 90% of Americans falling short on vegetable intake, there’s a clear need to help people enjoy more vegetables each day, including nutrient-rich potatoes.

Bottom Line

Research that examines single foods in isolation has limited value since that’s not how people eat in the real world. Nutrition experts are increasingly shifting their focus toward dietary patterns (rather than individual foods) because these patterns more accurately reflect actual eating behaviors and their relationships to health outcomes.

Before passing on the potatoes, it’s important to understand the facts of this particular study:

• Baked, boiled, and mashed potatoes are not associated with the development of type 2 diabetes.
• The methodology is unable to show that fried potatoes are a cause of individual risk of developing type 2 diabetes.
• The data show that there was no association between fry consumption and type 2 diabetes after 2010.
• The amount of fried potatoes associated with increased diabetes risk prior to 2010 is significantly more than Americans typically consume.

Potatoes in all forms have nutrients to fuel the body and mind and can easily fit into meals across various personal, cultural, and dietary preferences.

The average person consumes the equivalent of about 0.48 cups of fries per week, which is approximately 60 g. In the paper, a serving of fries was 4-6 oz or 113.2-169.7 g. The high consumers of fries in the paper consumed 566-859 g per week.

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[1] 2025 Dietary Guidelines Advisory Committee. 2024. Scientific Report of the 2025 Dietary Guidelines Advisory Committee: Advisory Report to the Secretary of Health and Human Services and Secretary of Agriculture. U.S. Department of Health and Human Services. https://doi.org/10.52570/DGAC2025

Total vegetable intake for Americans aged 1+ years is 1.5 cup-eq/d*, of which 4.61%^ is from French fries (i.e., 0.06915 c-eq/d). This equates to 0.48 c-eq/wk.

*from Part D, Chapter 1 of the report

^from the Basis Analysis data file from the Food Pattern Modeling Analyses

The average person consumes the equivalent of about 0.48 cups of fries per week, which is approximately 60 g. In the paper, a serving of fries was 4-6 oz or 113.2-169.7 g. The high consumers of fries in the paper consumed 566-859 g per week.