Two book recommendations.

The Omnivore's Dilemma by Michael Pollen

In Defense of Food by Michael Pollen

Eat food. Not a lot. Mostly plants.

Look at the ingredients. If it has any of the following, it isn't food but a food-like product. Avoid:
1. Anything with an ingredient you can't identify.
2. Anything with an ingredient you can't pronounce.
3. Anything with more than five ingredients.
4. Anything with high fructose corn syrup.

Now that's a diet everyone can follow.