Nutritional overview

Generally, a healthy diet is said to include:
1. Sufficient calories to maintain a person's metabolic and activity needs, but not so excessive as to result in fat storage greater than roughly 30% of body mass (see Body fat percentage);
2. Sufficient quantities of fat, including monounsaturated fat, polyunsaturated fat and saturated fat, with a balance of omega-6 and long-chain omega-3 lipids;
3. Maintenance of a good ratio between carbohydrates and lipids : four gramms of the first for one gramm of the second.
4. Avoidance of saturated fat (although the "evidence" for this claim is forever in debate after the testimony of results provided by the Framingham Heart Study of 1948-1998)
5. Avoidance of trans fat.
6. Sufficient essential amino acids ("complete protein") to provide cellular replenishment and transport proteins;
7. Essential micronutrients such as vitamins and certain minerals.
8. Avoiding directly poisonous (e.g. heavy metals) and carcinogenic (e.g. benzene) substances;
9. Avoiding foods contaminated by human pathogens (e.g. e. coli, tapeworm eggs);
10. Avoiding chronic high doses of certain foods that are benign or beneficial in small or occasional doses, such as
- foods or substances with directly toxic properties at high chronic doses (e.g. ethyl alcohol);
- foods that may interfere at high doses with other body processes (e.g. refined table salt);
- foods that may burden or exhaust normal functions (e.g. refined carbohydrates without adequate dietary fibre).
This Article from http://en.wikipedia.org/wiki/Healthy_diet