1.Food and Activity.
People gain weight when they eat more calories than they burn through activity.Moreover, lazy behaviour.
2.Environment.
The world around us influences our ability to maintain a healthy weight. Apart from that some weather and environmental conditions lead to such problems by becoming lazy towards exercise and works.
3.Genetics
Health Conditions and Medications. To elaborate, some medication and health condition play important role in such case. For example some medication effect body and leads to overweight.
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