Hourly fluctuations due to water weight is very normal in people because our bodies are made up of 60% water. So many factors will affect our water weight from sore muscles when we exercise to too much sodium in our foods.Are you keeping track of your calories? Many people find they need to even on Atkins because you can gain or not lose on Atkins if you take in more than your burning off. Are you drinking enough water? It can help flush out sodium, keep everything moving and running more smoothly. Are you using the bars and shakes? I've heard people say they have a hard time losing when they use them.