I am on girls holiday with friends from school. One dear friends weight is down to about 6.5 stone - we are all in our mid forties. She is complaining of always being cold and terrible headaches. She has been exercising every day and eating around 500 calories of food each day. She is absolutely skeletal and doesn't seem to notice, picking out oversize jumpers when shopping and worrying they won't fit. Should I gently say look are you OK? I'm worried she is dangerously underweight and putting strain on her organs. I genuinely want to help. Is there any advice on what I can do?