Just because they're a We Asked: Keri Glassman, R.D., a nutrition expert and founder of Nutritious Life.
The Answer: Regular old white potatoes are not inherently bad for you. One medium potato, baked with the skin, is under 200 calories and is a great source of fiber, vitamin C, B6 and potassium. When you peel them and fry them, or smother them in butter, cheese, sour cream and bacon bits, well, that's another story.
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There's a reason potatoes are the number one crop in the world; they're cheap, filling and tasty. But they get a bad rap because they're carb-heavy and look a lot like the white foods we're often told to avoid, such as white rice and white bread. Unlike those, a whole potato is actually a whole food, which is exactly what you want to fill your diet with. In order to reap the benefits, you have to eat them whole. That means leaving on the skin, which is a concentrated source of fiber and contains beautifying phytochemicals comparable to what you find in broccoli. It also means choosing a plain steamed or baked potato instead of French fries, au gratin or any other fat-laden preparation.
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At the end of the day, potatoes are still a starchy food that produces an insulin reaction, so if you overindulge, they can drive blood sugar levels down and leave you hungry again in a couple hours. You can game the system by cooking your potato and letting it cool, which increases the amount of resistant starch that stimulates satiety hormones to help keep you fuller longer. Can't stand the idea of potatoes without a pad of hot, melty butter? Stick to antioxidant-rich, low-glycemic-index sweet potatoes instead.