According to the OECD one in six adults in its 33 mostly rich member countries is obese (measured as a body-mass index of 30 or more). And the problem is not confined to human beings. Pets, too, are getting chubbier. True, some scientists now believe that getting fat may be a mechanism that protects the body, and that the health problems associated with fatness may not be caused by it but be another consequence, another symptom, of overeating. But there is also plenty of scientific evidence to suggest that stuffing oneself silly leads not just to a less svelte silhouette, but to more profound problems like cancer.