Pros: There's no need for sleep, which leaves ample time for exercise. The metabolic boost will burn extra calories.
Cons: They're illegal. They're addictive. They'll eventually ruin your life. They'll cause your teeth to fall out. They may cause heart attacks. They'll destroy your marriage, get you fired from your job, and turn you subhuman.
Decision: Stick with exercise, such as running, for weight loss.