Potatoes (and quinoa) are fine in moderation. Humans started eating a variety of tubers over half a million years ago. Once we could cook them, we immediately adopted them.

They come from traditional Andean diets.

Sweet potatoes come from traditional African diets. Tubers are fine.

Highly processed chips are the problem. Hyper-palatable junk is the problem.

Grasses, like corn, wheat, and shorgum, don’t forget rice, go to 10k and the rise of agriculture. It is the modern highly processed junk, like wonder bread, that is truly a serious problem.

The obesity epidemic started to take shape over the last fifty years. This coincides with chips, soda, and other things available 24/7. It also includes plastics and Insecticides which act like hormones.

It is going to get worse, as big food becomes a global problem and people eat this fast junk.

Humans evolved eating a lot of plant matter, with some animal protein. But traditional hunter gatherer societies still eat that way.

One secret to lose weight is to shift your day to day diet to a lot more plant matter. That includes whole grains, tubers etcetera. Just avoid refined junk. And also a lot of meat and fat.

Societies that are lean almost eat it as a side dish, not the main event.