Hi if your pal desires that flat belly, besides eating the right food Japanese style, she should also try this old fashioned exercise, which you might say is quite outlandish but it works perfectly.
its the Japanese squat for toilet, now i understand you getting queasy about it but you can do this, even if you are not in the loo, all you do is squat with your toes taking your weight, tummy sucked in, as far as you can go.
maintain the same position for a count of ten, rise and do it again, thats all i'm sure your pal would be thanking you, if not me.
now for more infor, check out the Japanese Culture site.
Japanese Culture Editor