My flatmate got contacted by some guy from her Instagram account about personal training. She has no experience or qualifications. The guy has been round once and she measured him up (kind of weird because we can see into her bedroom and he was in his underwear being measured). But this whole thing doesn't seem right.

I'm worried either: a) She will accidentally hurt him b) He's actually some kind of creep

The reason for a is because she only ever works out at home on a Saturday morning. Her workout is always the same so no doubt she has plateaued long before. But also her technique isn't particularly impressive and she isn't particularly fit. I assume the vast majority of it could be nutrition in which case she has even less skill. Her diet yo-yo's between protein everything and sugary sports drinks to pizza, frankfurters and coca cola for every meal.

The second is because the vast amount of nude and partially nude photo's on her Instagram. I don't really know why anyone would contact a stranger they know nothing about based on a series of photo's for training. Surely you'd join a gym and get a real personal trainer?

The main reason for having not said anything sooner is I don't want to deal with any repercussions. She's also argumentative, a little crazy and always right. So I'd rather avoid any confrontation if possible.

Yeah, he's not there for the 'personal training'. He's trying to get into her proverbial pants. This whole situation just makes my Creep-o-meter go DING DING DING DING. Sorry, just my opinion of course, but I don't see how it could be anything but.