There is a worldwide epidemic of obesity; moreover, obesity is increasingly recognized as a common condition that accompanies asthma. While both are common in westernized countries, there is evidence that obesity contributes to an increase in asthma prevalence. When obesity occurs with asthma, it is associated with an increased asthma severity, with poorer asthma control, increased asthma exacerbation risk and decreased steroid responsiveness. These effects are consistently seen and indicate that obesity contributes to an increased illness burden in asthma. The exact mechanisms connecting both conditions are not well understood up till now hence, the aim of this work is to put some light on this obscure relationship for better understanding and to motivate researchers for more effort to solve this challenge for the sake of those patients as new drugs may emerge to control this condition.