There are many environmental, social, physiological & behavioural reasons why people can be overweight & obese. The most basic reason however, is that the energy balance between what an individual eats (the energy in) & how that energy is used (the energy out) is uneven leading to excess energy being stored in the body as fat.
Because of this energy balance principle, people who eat a high-fat, high-energy diet & do not exercise will almost certainly gain weight. There are also a number of other reasons why some people gain excess weight more quickly than others.
- Body weight
- Food preference
- Hereditary factors/genetics
- Socio-economic factors/status
- Psychological factors
Overweight & obesity are more common in lower socio-economic groups, in rural & remote populations, in certain ethnic groups, & in Aboriginal & Torres Strait Islander people.