Now, you can eat as much as you like without putting on extra pounds. And you can even receive all the benefits of exercise without leaving the sofa. An all-in-one tablet is being developed to treat obesity, diabetes, heart disease and cancer. The drug, which is being made by the biotech firm Sirtris, could be available within three years. The excitement surrounds a family of drugs based on resveratrol, the “miracle ingredient” in red wine credited with inhibiting the development of cancer and heart disease.