Meal components

I've always had the idea that food charts were a bit off. Every meal I've seen so far only contains 3 real types of ingredients.

Fruits, vegetables and legumes. The "green" stuff. Plants that give you vitamins, minerals and fibre, while being low in calories, so you can essentially eat a lot of them without ill effect.

Meat, fish, eggs and other sources of protein and fat. (I'm still unsure about tofu) These satiate hunger very well (Fat and protein do that) and contain those proteins you need to keep your body going. It kind of makes sense, that the best food to sustain your body is another body, as it is made of the same stuff.

And lastly, there's what I call filler: Pasta, potatoes, bread, rice, etc..
These generally give you the bulk of your energy, having a high caloric content based on carbohydrates ('carbs'). Not that there is anything wrong with calories, you need energy to live, to work and to thrive. Bread is an excellent example, a staple of humans for ages, it is essentially a slab of carbohydrates that you can take to your work so you can refill the energy you spent labouring all day.

But if you want to lose weight or want to try things like primal (paleo) eating, low-carb, or tim ferris' diet, it makes sense to cut out the bulk of energy from the diet by eliminating the filler category.

(Plus, you'll have to up your intake of greens and protein-sources a bit, so you actually do get enough energy. Which are the most tasty part of any meal. Yum!)