Why lose weight? The benefits of weight loss and how to do it safely. By Adam Brook, M.D., Ph.D.

There are many health reasons why one should lose weight. Being overweight or obese causes or contributes to a large number of diseases, including heart disease33,34, certain types of cancer35, and diabetes36. (Body Mass Index is a way to assess whether someone is normal weight, overweight, or obese and will be discussed in the next chapter. A Body Mass Index between 19 and 24.9 is normal, and a Body Mass Index of 25 or over is overweight.)