You get the calories through good healthy fats. Eat extra virgin coconut oil, EFA oils like flax and cod liver, extra virgin olive oil, and pure butter. This goes against politically correct nutrition, but it is what you need. Dont cook with the
EFA oils, they go rancid easily. Your liver might have trouble digesting the fat at first (mine is) so take some liver supporting herbal products, like LivAmend from body ecology. Eat good animal protein too.