A big huge YES. This exactly what happens to me hun. I threw up my entire pregnancy and was 10 kgs lighter after DD was born but the same size clothes as I was before . Then started weight watchers as a friend was having great results, she lost 10kgs in 9 weeks without exercise. I stuck to it, walked 2kms everyday and in 9 weeks I lost....wait for it.....2kgs . It is so crappy and makes me furious! Big , it is heartbreaking when you try so hard and get nowhere!