In my experience, food groups like meats and carbs aren't totally bad. It depends on preparation and the amount of processing it goes through. I also side with the idea of that everyone's metabolisms are different - some people can get lean eating a lot of meat, others maybe can't deal with animal fat, for example.    I'm on the low end of the acceptable weight range for my height (where I want to be), and there's nothing in my fridge that couldn't have existed in 1900. Most people eat a lot of highly processed foods and fast food then wonder why they gain weight.    Some traditional foods have rather high calories, even if they're made from scratch, so portion size comes into play. The portion sizes in restaurants are crazy, and some of us grew up with finish everything for your plate parents, so most people are accustomed to eating way more than they actually need.