What is the best prescription weight loss medicine and why? Using it only as a starting point coupled with diet and exercise. Sometimes the first step is the hardest.

Complicated question. Unfortunately, there are no great options. Many meds have been taken off the market for safety concerns. The few that are left have their own side effect profile (cardiovascular risk, potential for addiction) and most studies show that the weight is regained after the medicine is stopped. The fda approved a new med recently - lorcaserin - but they are requiring more safety data.
Weight . As we age we loose muscle mass , we gain fatty mass (specially on the belly). We become less active & gain weight. We do healthy lifestyle to preserve what we have, but eventually you'll gain weight, get old and pass away. Positve mental attitude (pma) is the key. Diets are overrated. Are you ready to have pma? Whatever discipline you choose for preservation has to be fun and to your liking.
See doc. Lorcaserin was recently fda approved. Choosing the right med for you needs to be tailored to your situation. You will need to see your doc anyway since meds require rx.