Eating French fries often raises diabetes risk, Harvard study warns

A study tracking 200,000 US adults reveals eating French fries three times a week can increase type 2 diabetes risk by 20% while boiled or baked potatoes show no such link when eaten in moderation

French fries are a go-to comfort food for many. However, the medical researchers say this beloved snack raises the risk of type 2 diabetes.

 

A study titled 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, published in the peer-reviewed medical journal The BMJ, tracked over 205,000 US adults for 30 years. It found that French fries were strongly linked to a higher risk of type 2 diabetes, while baked, boiled, or mashed potatoes were not.

 

The research team from Harvard TH Chan School of Public Health also found that swapping fries for whole grains like brown rice or quinoa cut the risk, but replacing them with refined carbs such as white rice did the opposite.

 

What did the study find?

Participants regularly reported how often they ate potatoes in different forms, such as French fries, baked, boiled, or mashed.

 

Over time, 22,299 participants developed type 2 diabetes. The researchers adjusted for lifestyle factors like physical activity, body weight, and overall diet to isolate how potatoes themselves influenced risk.

 

According to the study,

• eating three extra servings of potatoes per week was linked to a 5 per cent higher risk of type 2 diabetes.
• eating French fries three times a week was linked to a 20 per cent increase in diabetes risk. Those eating them five or more times a week had a 27 per cent higher risk.
• baked, boiled, or mashed potatoes showed no significant increase in risk, making them a safer choice than fries.

The study also ran 'substitution models' to see what happens when potatoes are replaced with other carbs. The researchers found:

• Swapping potatoes for whole grains lowered diabetes risk by 8 per cent.
• Replacing French fries with whole grains dropped the risk by a striking 19 per cent.
• Replacing potatoes with white rice actually increased risk because of rice’s high glycemic index.

So, should you stop eating potatoes?

Not at all. The researchers said it is not about cutting potatoes out completely, but how you eat them. Boiled, baked, or mashed potatoes, especially when eaten with the skin, still offer valuable nutrients like Vitamin C, potassium, fibre, and antioxidants.

 

But French fries? Best kept as an occasional treat, not a staple. Eating them too often nudges your blood sugar levels up and raises long-term diabetes risk.

 

Healthier swaps for potatoes

If you’re looking to balance your plate, try:

• Whole grains: quinoa, farro, brown rice, or barley.
• Non-starchy vegetables: broccoli, beans, spinach, or carrots.
• Legumes: chickpeas, lentils, or kidney beans.

This current study reinforced that not all carbs are equal. French fries may be delicious, but swapping them out a few times a week for whole grains or veggies could make a real difference for your long-term health. 

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This content is for informational purposes only and is not a substitute for professional medical advice.