Carbs
Way back in the early 1990s, Nabisco made hundreds of millions of dollars selling the low-fat, sugar-packed Snackwells line of cookies and crackers to Americans who had been taught to believe fat was evil. The nutritional pendulum has since swung the other way—popular low-carb diets have followers choosing meat (paleo and Atkins diets) and fat (keto diet) over sugar.
Extremes are typically a bad idea: Although cutting added sugar (such as that in processed food) from your diet makes sense, most researchers agree that healthy carbohydrates (like those in produce and whole grains) can play an important role in any healthy diet.