Asthma and obesity in adults and children are increasing worldwide public health problems, especially in developed countries. Obese and overweight children have increased rates of both atopic and non-atopic wheezing due to a variety of known and proposed mechanisms. These include reduced lung volume and airway caliber due to increased chest wall mass and possible airway inflammation from systemic inflammation as a result of increased adiposity that includes macrophage accumulation and the effects of the proinflammatory energy-regulating hormone, leptin. Comorbidities that aggravate wheezing include gastro-esophageal reflux disease, type 2 diabetes, metabolic syndrome, and, possibly, dyslipidemia. Children with asthma and obesity appear to be more resistant to both outpatient and inpatient medical treatment and weight loss is the definitive therapy.