help for teen who overeats

My 15-year-old daughter has put on a significant amount of weight in the past four months -- in the order of 15-20 pounds.  She gets very angry if anyone comments on what she's eating or how much.  Any junk food in the house is minimal -- occasionally something like ice cream.  She knows about healthy eating habits, but seems to rationalize all her unhealthy habits.  She also seems to be in denial about her weight gain and feels that she is not overweight.  Am I overreacting?  What is the best approach to getting her to make better choices regarding foods and serving sizes?

[Renee Radenberg]

She is in puberty and this is the time when she will be gaining weight as she develops. Her weight is just below the 95th percentile and her height is on the 90th percentile for her age. If you are concerned about her weight then it is recommended to increase children's physical activities to lose weight. Have your child go do running, walking, sports, and etc. Limit time in front of the TV or non-active-video / computer games. There have been studies showing the longer the length of time a child sit in front of the TV, the greater the weight gain. Suggest you do limit high sugar drinks/snacks and replace with low-fat milk/yogurt or fresh fruit/air-popped popcorn/low-fat cheese. High sugar drink and snacks do not give the child nutrients they need. Eat low fat meats (chicken, fish, loin of pork) or non-meat sources (soy products, nuts), low fat vegetarian combinations (rice & beans, pasta & beans, low fat cheese & pasta), substitute dairy products (low fat soy milk/soy yogurt), use plant oils, non trans-fat margarines, and eat a lot of fruits and vegetables. Eat daily high fiber breads and cereals (oatmeal).