Obesity can be defined as an excessive or abnormal fat accumulation which may impair health. It is recognized as a top public health issue and it is ranked as the 5th foremost cause of death worldwide. The current review set out to summarize the studies which provide basic information about the obesity prevalence in Iraq (adults, children and adolescents); moreover, it set out to address the impact of obesity on multiple health conditions. It is now demonstrated that obesity (dependent upon the duration, distribution, and degree of the excess adipocytes/weight) may progressively exacerbate and/or cause a wide range of comorbidities. This review discusses the contributions of obesity toward the pathogenesis of type II diabetes, insulin resistance, metabolic syndrome, and COVID-19 in addition to other diseases.