My 12 year old daughter is 5'1 and 140 pounds. is that considered overweight? and if so, what can i do about it?

Yes: Her BMI is elevated. She needs aerobic exercise at least 4 times a week. Low fat milk & diet. No juices, soda Gatoraid or junk food. More fruits and vegetables & less complex carbohydrates. Turn off electronics & get outside. Same thing that we as adults would do.

Yes: Technically yes. 140 lbs is overweight however you have to factor in her body composition. Combining consistent daily exercise with calorie control using healthy food can maintain this weight as she grows or be used to reduce her weight now.

Yes, her BMI is >95%: BMI is a body proportion index and above 85% is overweight. Unless she is already getting her periods, the focus should be on not gaining any more weight. Increase the activity, increase the veggies and fruit in her diet and reduce pop, juice, snack food and cut back on the portion size of breads and fats. If she gained 15 pounds last year, cut back 150 cal/day to stay even or lose.

Overweight: Your 12 year old daughter at 5feet and one inch and weighing 141 lbs is overweight. At this age you and she still have more choices to do something about it than you would have at say 18 years, if this trend would continues. While BMI shouldnt be looked in isolation, it would be a good idea to have a discussion with her pediatrician to develop a plan for her weight reduction w diet and exercises.