The idea was that people ate for winter, because during the winter food was more scarce. That is the purpose of body fat in the first place, to provide energy when food is scarce. Bears eat nuts and berries to fatten up so they can hibernate during the winter, when those aren’t available.
But that’s not an issue anymore. Now all kinds of foods are available 24/7 365 days a year. And so there is no longer the need to fatten up by eating carbs.
good logic.