Obesity is known to cause physical and metabolic diseases. It is often assumed by people (including the healthcare workers) that the person with obesity lacks self-control in matters of diet and physical exercise, and is therefore responsible for his or her weight. Persons with obesity have to face sarcasm, barbs, and discrimination due to their condition. They often have difficulty in getting jobs or have to accept lower than standard pay for their work. Although weight gain requires calorie intake in excess of calorie expenditure, it is sometimes not easy for the person to restrict calories due to the underlying causes of obesity. The body resists losing weight, and attempts to hoard calories by reducing the metabolic rate. In this chapter we have explained and classified the causes of obesity into endogenous and exogenous. The endogenous causes include genetic and epigenetic causes, maternal factors, and hormonal causes, while exogenous causes include obesogenic environment, lifestyle, and weight-gain promoting medicines. It must be realized that losing weight and keeping it off is not easy for a person with obesity.

Increase in body weight due to excess accumulation of fat can lead to obesity, a chronic, progressive, relapsing, multifactorial, neurobehavioral disease caused by adipose tissue dysfunction. Obesity often results in adverse biomechanical, metabolic, psychosocial, and economic consequences. In humans, effects of obesity are diverse and interrelated and can be classified on the basis of organ/organ system affected. Physical problems associated with weight gain are musculoskeletal problems, respiratory problems, lower limb venous diseases, skin-related problems, and stress incontinence in females. Metabolic conditions caused by obesity include gout, insulin resistance and metabolic syndrome, type 2 diabetes mellitus, certain cancers, CVD, fatty liver, gall bladder disease, etc. Obesity is known to affect the reproductive health. Hypogonadism and pseudo-gynecomastia are more common in males with obesity. Decreased fertility is reported in both the sexes. Polycystic ovarian syndrome (PCOS), anovulation, endometrial hyperplasia, and increased risk of complications in pregnancy have been reported in females. Persons with obesity have increased healthcare expense, pay more insurance premium, take more illness-related leaves, thus suffering economic loss due to their condition. Persons with obesity are often considered legitimate targets for teasing and bullying, which may cause social isolation, depression, eating disorders, etc. Obesity affects the morbidity and mortality. This chapter deals with the different consequences of obesity.