Food is any material eaten to supply nutrition to an organism. In humans, food is generally of animal, plant or fungi origin, and usually contains nutrients, including proteins, vitamins, carbohydrates, and minerals. The nutritional value of food is measured by calories per serving, which is the amount of energy needed to do one serving of food. The calorie content of food is listed on the label either in whole or in part, and may be expressed as (grams) per serving.

The absorption of nutrients from food depends upon the physical nature of the food and the physiological response it triggers in the body. Nutrients loss or gain is a normal part of the metabolic process and is a cause of weight gain or loss. Thus, in terms of food safety, there is a relationship between absorption and food security. The nutrient content of food and the methods of food preparation have direct effects on absorption and nutrient retention; the foods that are easily digested are considered better for human consumption, while those that are more difficult to digest are bad for nutrition.

According to the United Nations Food Security Network, nutrients loss due to gastric bypass surgery are associated with the lack of hunger. This means that patients who have undergone gastric bypass surgery are not able to feel the necessity for food. Although this feeling of hunger disappears when food is eaten, the prolonged period of time during which a person does not feel hungry may lead to vitamin deficiency or even malnutrition. As a result of this deficiency, people may suffer from serious health problems.

Food intake requires the body to have certain foods, like carbohydrates and proteins, to be processed for energy. Carbohydrates are available in many forms, in the form of cereal, bread, rice, pasta, fruit juice, and vegetable juice. The average carbohydrate is glucose, which can be converted into energy by the liver through the use of insulin. However, the presence of insufficient carbohydrates in the diet, especially in people with diabetes, may reduce the production of insulin or may make the process of insulin resistance or type II diabetes probable.

Another group of food components essential for nutrition is dietary fiber, found in fruits, vegetables, legumes, whole grain foods, nuts, seeds, and soybeans. Deficiency in dietary fiber results in poor food digestion, constipation, diarrhea, and bloating. These conditions may eventually lead to colon cancer, gallbladder disease, high blood pressure, and irritable bowel syndrome (IBS) – a severe intestinal disorder. The lack of adequate nutrition can also contribute to osteoporosis, especially in women.

The recommended daily allowance of food, according to the American Heart Association, is a combination of carbohydrates, protein, unsaturated fats, and fiber. A balanced diet consisting of these food groups ensures good health, although the food may not be as satisfying as it could be if all the food groups are not consumed. For example, an egg yolk contains only about one gram of protein, but eating the egg white without any egg yolk may provide enough protein for a satisfying breakfast food. Therefore, vegetables, fish, legumes, nuts, and eggs are excellent choices for food that satisfy hunger.