Obesity and overweight are major health concerns and the leading preventable cause of death in developed and developing countries. Obesity affects men and women differently due to biological, socioeconomic, cultural and country-specific gender-related disparities. This book chapter outlines obesity as a risk factor for physical diseases and mental health disorders in women. Obesity has been shown to contribute to the risk of certain types of cancer, including breast, endometrial, gallbladder, oesophageal and renal cancer. In terms of reproductive health, obesity negatively affects both fertility and contraception. In addition, obesity is associated with early miscarriage, higher rates of caesarean section and high-risk obstetrical conditions, in addition to higher maternal and neonatal mortality rates, and congenital malformations. In terms of mental health, obesity is closely linked to depression, anxiety disorders, neurodegenerative diseases and sleep disorders. Socioeconomic, psychosocial and behavioural factors, factors associated with ageing, mechanisms related to the microbiome, gastrointestinal and vascular system, intracellular pathophysiology and metabolism in the body, hormones, adipocytokines and problems associated with medical treatment are important factors linking obesity with its negative consequences on physical and mental health.