Most Americans eat a "balanced diet" in terms of carbs and fats--and that's not working out well. We can point to processed foods, but the truth is eating both fat and carbs isn't a good idea (see Randle Cycle). The reason we crave carbs is mostly because the ones we eat (i.e. pizza) are addicting, include sugar, and burn fast. Metabolically flexible people are extremely rare in the US - but prediabetes and diabetes are epidemics! Research shows we can stop and reverse both metabolic diseases with a low carb/keto diet in which the fuel source is fat. We don't need carbs; we lived through the Ice Age without them