Childhood and adolescent obesity are significant global public health concerns. In recent decades, the Israel Medical Corps, in collaboration with other health organizations, initiated studies regarding the obesity epidemic in Israel, characterized specific groups that are at-risk for obesity and analyzed the short- and the long- term risks for associated medical conditions among those with obesity. According to these data, adolescent obesity and severe obesity prevalence have increased by 4- and 20-fold in the last decades in Israel, respectively. Low socioeconomic status, low level of education and low cognitive function were associated with a higher risk for obesity. Adolescents with obesity are at greater risk than those with normal weight for hyperhidrosis, asthma, different orthopedic abnormalities, hypertension and type 2 diabetes. A longitudinal study that followed the adolescents for 11 years has demonstrated a significant risk for adolescents with obesity for type 2 diabetes with hazard ratios (HRs) of 13 to 45, depending on sex and obesity degree. Longitudinal studies reported hazard ratios of 7 for end-stage chronic kidney disease, 1.3 for cancer, 3 for ischemic stroke and 7 for coronary heart disease in adulthood for adolescents with obesity compared to those with normal weight. Adolescents with overweight and obesity had greater risk for all-cause mortality in adulthood. Given the alarming increase in the prevalence of obesity and the significant short- and long- term consequences of adolescent obesity, the burden of the economic and clinical services on the healthcare system is expected to rise.