You are eating not enough for your body and when that happens the body 'preserves' what it has. Metabolism does slow down, however, without enough food the body will start to break down protein and water will increase in the body. Suggest a measuring tape and not a scale. As you exercise you build lean muscle which weights more than fat. You may not see weight go down, however, your clothes size will go down. Suggest you start eating 5-6 small meals a day at 100-1200 calories per day so your body has all the nutrients it needs to be healthy.