yeah your friend might have lost all that weight by starving herself but as soooooon as she starts eating again, she'll put it alll back on and more. haven't you ever heard of a 'yo-yo dieter'? they appear in, like, Take A Break magazine and they're a size 20 but in the course of their lives they've lost, like, 1000 stone. it's sad.
bah i hate exercise too. i'd die ahead of go to a gym. do stuff like: walk instead of getting the bus, if it's only a few miles and it's daylight and all that. or get off the bus a stop early, they always say. i used to walk home from work in the summer (about 6 miles) and every time a bus would go past i'd be like "shoooould i...flag that down?" but then when i'd walked all the way home i'd be well pleased with meself. and the busfare would be saved for haircare yay.
everyone says you should avoid bread and pasta and stuff. i say you should avoid meat. that's not based on any dietetic information, it's just filthy stuff and everyone knows the stereotype of the skinny, emaciated vegetarian.

quorn and the other meat substitutes are low-fat and much easier to cook than meat. and some of them are soooooooooooo gooooooood. try holland&barrett for the most amazing "bacon" rashers (and grill them!!).
starving yourself's shit cos you end up cracking and then thinking "oh, fuck it, then". these magazine diets say "have one or two squares of chocolate for a treat" but that would actually be worse for me haha. have fruit for treats. mm and pretzels instead of crisps. mmm and artichokes and olives and humous instead of greasy pizza.