i have a 16 month old gsd girl, that i think looks very skinny , she's only a small girl and weighs in at 26kg, i have tried to put weight on her by feeding her 3 times a day , but she's just one of those dogs that goes loose in her motions if she's given more food, she is on csj food at the moment , she is a very active hyper girl that never sits still , i just wish she didn't look like a rspca case , also she is wormed every 3 months with drontal, thanks

just feed her twice a day shes runny because shes getting to much food and try giving her raw meat or tripe

tripe is good for putting on weight but try a little and see how she goes if she is prone to tummy upsets...as previous poster says loose toileting  maybe because she is having too much food .If she seems fine with it then give it with her normal meal and feed twice a day...