A healthy diet contains a balance of food groups and all the nutrients necessary to promote good health. Human nutrition is enormously complex and a healthy diet may vary widely according to an individual's genetic makeup, environment, and health. Healthy eating is the practice of making choices about what and/or how much one eats with the intention of improving or maintaining good health. Typically, this means following recommendations for a healthy diet. The concept of healthy eating is primarily a problem in rich countries where the lifestyle includes a modicum of outdoor physical activities, high but not always high-quality food consumption, and a trend towards industrially-produced foods instead of locally-sourced, locally-prepared meals.