As long as the protein is high you won't be losing muscle.itl just be the water etc that you have put on.if you want to keep the cals a bit higher add a tablespoon of flaxseed oil or olive oil to each meal.I was up at 16st 5 and looked great in a t shirt.but its amazing how much crap you can actually hold.now just over 14st and tho I feel skinny with a t shirt on I'm looking way better without.