Diet (nutrition)

In nutrition, a diet refers to everything a person or other organism eats. While the term often suggests a specific eating plan for health or weight control, it simply describes total food intake. Humans are omnivores, but personal taste, ethics, and culture shape food choices and taboos. Some diets are healthier than others. To be complete, nutrition must include vitamins, minerals, essential amino acids from protein, essential fatty acids from fats, and energy from carbohydrates, protein, and fat. What and how we eat strongly affects quality of life, health, and how long we live.

A healthy diet supports both mental and physical health. Certain diets, like the DASH diet, help manage chronic conditions. Many countries offer dietary recommendations that promote balanced, culturally appropriate eating. These differ from dietary reference values, which focus on preventing nutrient deficiencies. As of 2025, only 30.8% of children aged 6 to 23 months and 62.7% of women aged 15 to 49 consume a minimally diverse diet.

Some people choose exclusionary diets, avoiding certain foods for health, moral, or environmental reasons. Examples include flexitarianism, pescetarianism, vegetarianism, and veganism. A balanced vegetarian or vegan diet can provide adequate nutrition, but may require extra attention to protein, iron, calcium, zinc, and vitamin B12. Raw foodism and intuitive eating are other approaches. Education, income, local food availability, and mental health all influence dietary choices.

Diets are also used for weight loss or gain. Changing food intake alters energy balance and body fat storage. "Healthy diet" and "diet for weight management" often overlap, as both promote healthy weight. Overweight or obese individuals who adopt a diet that burns more calories than consumed may improve health and reduce risks for heart disease and diabetes. Obesity rates have risen nearly 10% in the past decade. Conversely, underweight individuals due to illness or malnutrition may eat more to gain weight. Intentional weight changes can be harmful if too rapid. Unintentional rapid weight change may result from medications or signal serious conditions like thyroid issues or cancer.

Red meat—pork, beef, lamb—and white meat from chicken and turkey are common in Western diets, providing energy, protein, vitamins, minerals, and fatty acids. Meat can be processed with preservatives, smoking, curing, salting, fermenting, or canning. The International Agency for Research on Cancer states processed meat causes cancer, especially colorectal cancer, and red meat is a probable cause. Strong evidence links processed meat to higher risks of cardiovascular disease and type 2 diabetes. The World Cancer Research Fund advises limiting red meat to three servings per week and minimizing processed meats.

Agriculture drives environmental problems like biodiversity loss, climate change, desertification, soil degradation, and pollution. The entire food system—including refrigeration, processing, packaging, and transport—accounts for about a quarter of greenhouse gas emissions. More sustainable choices, such as eating less meat and dairy and more plant-based foods, and choosing foods from sustainable farming, can reduce this impact.

Religious and cultural rules also shape diets. Judaism permits only Kosher foods; Islam allows only Halal foods. Buddhists are often vegetarian, but practices vary. Hinduism idealizes vegetarianism. Jains are strictly vegetarian and also avoid roots like potatoes and carrots. Christianity has no general animal restrictions, though some groups follow specific rules. Common Christian diets include the Mediterranean diet and vegetarianism, both linked to balanced nutrition and better health.