If French fries come from potatoes, and potatoes are a vegetable, and vegetables are good for you, then what’s the harm in eating French fries?

Plenty, say experts and nutritionists, including Eric Rimm, a professor in the departments of epidemiology and nutrition at the Harvard T. H. Chan School of Public Health, who called potatoes “starch bombs.”

Potatoes rank near the bottom of healthful vegetables and lack the compounds and nutrients found in green leafy vegetables, he said. If you take a potato, remove its skin (where at least some nutrients are found), cut it, deep fry the pieces in oil and top it all off with salt, cheese, chili or gravy, that starch bomb can be turned into a weapon of dietary destruction.

A study last year in The American Journal of Clinical Nutrition noted that potatoes have a high glycemic index, which has been linked to an increased risk of obesity, diabetes and cardiovascular disease.