2. Exercise controls calories.
"It's pretty simple: You need to burn more calories than you consume in order to lose weight," says Nancy Snyderman, MD, a FITNESS advisory board member, editor-in-chief of BeWell.com, and chief medical editor for NBC news. Regular exercise blasts excess calories that would otherwise be stored as fat. "Plus, you continue to burn calories even in the hours following your workout," says Dr. Snyderman.