Health is a condition of psychological, physical and social well being where infirmity and disease are absent. Different definitions have been used for many purposes over the years. In recent years the National Institute of Health (NIH), in collaboration with the National Center for Complementary and Alternative Medicine (NCCAM), has produced a series of guidelines on the definition and maintenance of the standard definition of health. The definition of health is a summary of the science that integrates understanding of human biology, nutrition, medical knowledge, and psychosocial concerns. According to this definition, health is the sum of the whole body’s health and its function that is maintained by appropriate food intake, active lifestyle, and a reasonable amount of physical activity for an individual’s capacity to attain health and the ability to preserve health.

According to the current NCCAM guideline, five major determinants are important in determining a person’s health status: age, body size, genetic and physiological features, lifestyle choices, and environmental risks. The five determinants help to explain how and why diseases develop or progress. For example, as people get older their weight increases and decreases because of the impact of age and general health declines. Similarly, genetically determined differences between people lead to differences in BMI that can lead to different health risks or goals. Lifestyle choices or habits also have a direct impact on health and these include the amount of alcohol and caffeine that a person consumes, whether or not a person engages in regular exercise, and the frequency and duration of use of recreational drugs such as marijuana and heroin.

The above factors are considered to be determinants of health status. In addition, they are associated with the five defining features of health – age, body size, genetic and physiological features, lifestyle choices or habits, and environmental risks or threats. These features may be thought of as the underlying structure underlying health disorders and health conditions. There is much ongoing research in the field of health and disease, ranging from basic studies to more complex and advanced studies.