Losing weight

Ever since I went on vacation I've gained 3-5 lbs and I REALLY want to get rid of it. I also have a thick rib cage so I look even more chubby. Is there any good ways to lose weight? I take diet pills after meals but they work very little. I've tried eating less but not really helping. I tried starving myself one day but I realized that doesn't do well either. I'm gonna try going to the gym pretty soon but I want to do something else that will make me lose weight also. Help?