A significant increase in the prevalence of obesity has occurred worldwide and the importance of considering the role of diet in the prevention and treatment of obesity is widely acknowledged. A growing body of evidence encourages the consumption of ready-to-eat cereals (RTEC) as part of a healthful diet. Research has shown an inverse association between the consumption of RTEC and the rate of obesity. However, other findings claim that this association was only attributed to the consumption of whole-grain cereals and not the refined-grain ones. Although meta-analyses of clinical trials support the use of a low-glycaemic index diet on weight loss, findings from other studies on the effect of the dietary glycaemic index on body weight have not been consistent. Thus, further research into the role of glycaemic index in the prevention and management of obesity and chronic disease is needed. Moreover, significant differences have been observed in composition among the marketed RTEC. In light of the revealing protective role of whole-grain, fibre-rich, low-energy-dense and low-glycaemic index/glycaemic load foods against obesity, public health professionals could drive their efforts towards the promotion of even more healthier RTEC when issuing advice on weight management. It seems, however, that despite any differences in their composition, the frequent consumption of RTEC due to their nutritional contribution is recommended in moderation and under the current recommendations in the context of a healthy balanced diet.