In nutrition, diet is the sum of food consumed by a person or other organism. Dietary habits are the habitual decisions an individual or culture makes when choosing what foods to eat. With the word diet, it is often implied the use of specific intake of nutrition for health or weight-management reasons (with the two often being related). Although humans are omnivores, each culture and each person holds some food preferences or some food taboos, due to personal tastes or ethical reasons. Individual dietary choices may be more or less healthy. Proper nutrition requires the proper ingestion and, equally important, the absorption of vitamins, minerals, and food energy in the form of carbohydrates, proteins, and fats. Dietary habits and choices play a significant role in health and mortality, and can also define cultures.
Diet and life outcomes
A three-decade long study published in the British medical journal, The Lancet, found that Guatemalan men who had been well-fed soon after they were born earned almost 50% more in average salary than those who had not. The blind trial was performed by giving a high-nutrition supplement to some infants and a lower-nutrition supplement to others, with only the researchers knowing which infants received which supplements. The infants that received the high-nutrition supplement had higher average salaries as adults.
Diets for weight management
A particular diet may be chosen to seek weight loss or weight gain. Changing a subject’s dietary intake, or “going on a diet”, can change the energy balance and increase or decrease the amount of fat stored by the body. Some foods are specifically recommended, or even altered, for conformity to the requirements of a particular diet. These diets are often recommended in conjunction with exercise. Specific weight loss programs can be harmful to health, while others may be beneficial (and can thus be coined as healthy diets). The terms healthy diet and diet for weight management are often related, as the two promote healthy weight management. Having a healthy diet is a way to prevent health problems, and will provide your body with the right balance of vitamins, minerals, and other nutrients.
A healthy diet is one that is arrived at with the intent of improving or maintaining optimal health. This usually involves consuming nutrients by eating the appropriate amounts from all of the food groups, including an adequate amount of water. Since human nutrition is complex, a healthy diet may vary widely, and is subject to an individual’s genetic makeup, environment, and health.
Source and References http://en.wikipedia.org/wiki/Diet_(nutrition)