Throughout history, obesity has been perceived in different ways, sometimes asa symbol of health and prosperity, and sometimes as a disease. Nowadays, thereis consensus in considering it as a chronic disease characterized by excessive fataccumulation and linked to cardiovascular diseases, diabetes and pregnancycomplications. It is most commonly diagnosed by means of the Body Mass Index(BMI). BMI often does not accurately reflect the problem. For this reason, othermethods such as Bioelectrical Impedance Analysis (BIA) and Dual Energy X-rayAbsorptiometry (DXA) have been proposed. Anthropometric parameters such asskinfold thickness and mid-arm circumference are also used. Obesity is a global publichealth problem whose prevalence has been increasing in recent decades. In Peru, itis estimated that two-thirds of women of reproductive age have a BMI ≥ 25. Thereare genetic and environmental factors involved in the development of obesity. Themetabolic changes associated with obesity are reviewed, including hyperinsulinemiaand hyperandrogenism, increased leptin and other pro-inflammatory adipokines,and decreased adiponectin. Obese women have a higher risk of developing insulinresistance, type 2 diabetes mellitus, dyslipidemia, coronary heart disease and highblood pressure. The prevalence of menstrual irregularities due to anovulationand infertility increases, with a lower rate of live births in in vitro fertilization (IVF)treatments, and an increase in the abortion rate. Postmenopausal women tend togain weight, due to hormonal changes and less physical activity, with a preferentialincrease in visceral fat. In obese women, the risk of breast, endometrial andovarian cancer increases. Obese pregnant women have a higher risk of developinggestational diabetes and preeclampsia, fetal macrosomia and congenital anomalies.It is important to prevent obesity with early education programs regarding theshort- and long-term medical consequences of obesity, and the promotion ofhealthy lifestyles. Treatment includes diet and exercise, and medical and surgicalmanagement options.