Secretive weightloss tips?

My friend (yes I promise this is my friend) Is 5'4" with a weight of 140, which means her BMI is 24.0. Her age is 13 as of October. She asked me to help her, and ask Yahoo Answers, with how to loose some weight. Her stomach bulges out, her thighs enlarge a lot when she sits, and when she waves, her arms jiggle. The main problem is that she can't wear shirts that look good because her bulging stomach sticks out too much to wear fitted clothes. She is very embarrassed about this issue, so she doesn't really want any one to know she is going on a diet or exercising more. She tells me that she is willing to do all this, but with out the help of a gym or special weight loss foods. At home exercises and foods that could be found around the house are ideal. She is 13 so no going out a buying things. She wants to reduce the size of her stomach, at the least. If you have some exercise tips, then please share them. She also says that she knows how to eat and manage eating. Thank you if you have contributions!