I know this is quite old but still. I am a Bulgarian girl, I am slim and I eat a lot (actually I can't concentrate if I haven't eaten for 5-6 hours and I need to spend a lot of money on food which can be quite frustrating but I don't really complain). 
The truth is in the USA you eat toxins. And you have been told lies about what is healthy and what is not. You've been told that saturated fat is bad (research shows it's not but the media will never tell you). You've been told that low-fat dairy is healthy. You've been told that vegetable oils are healthy. You've been told that soy in ridiculous amounts is healthy. You've been told that meat is bad and should be avoided (there are many traditional cultures that are completely healthy and their diet consists of animal food ONLY, they are free from modern disease like obesity and that's a fact!!!). You also have easy access to all kinds of refined foods - refined white flour, refined sugar, etc. that are very addictive and they cause many, many problems. And don't even get me started on high fructose corn syrup.
In Bulgaria we've been told the same but many Bulgarians just don't care and continue to eat the traditional food because it tastes good. Also, many Bulgarians grow their own food, they buy milk and meat from their friends or people they know. So they have a diet based on whole, real foods without even trying. They just continue the tradition and traditionally prepared food is just more healthy. Also, refined and highly processed foods are expensive (some even consider McDonald's a fancy restaurant) while in the USA they are so easily available. Well, unfortunately, Bulgarian diet is getting worse and worse but still not as bad as Standard American Diet (SAD).
You can google SAD and also make your own research on why eating fat in the form of butter, lard, coconut oil, etc, is not bad, why low fat dairy is not good for you, why red meat is not harmful at all but very nutritious, why vegetable oils make you fat, why fermented foods are very good for you and your gut (and Bulgarians love preparing them and eating them), why bone broth and liver are some of the best foods you can eat ever and so on and so on. In short - eating traditionally prepared food is good for you. Eating a diet consisting of whole foods in their natural state is good for you. But of course, soy oil and high corn fructose syrup manufacturers wouldn't be happy if you knew that. You can see it with your eyes - people eating meat and cheese are not fat. I am 52 kg and I eat meat twice a day (I don't like chicken, I eat mainly pork). The heaviest me was 56 kg and that was because of eating too much gluten. Since I went gluten and toxic foods free I just don't put on weight no matter how much (real) food I eat. Well, of course, this also has to do with genetics and the fact that I am small framed, I also never skip breakfast but it is not only that.
I'm telling you again - make your research on what modern science has to say. You'll be surprised.