Well, your body is made up of 60% water, so many things can factor in to make your weight fluctuate. If you eat too much sodium one day, you can be up the next. Working out gives you sore muscles which retain water to help them heal and you can show a temporary gain. Hormones, medications, stress, etc. can all effect our weight. If you are on plan, the you know it's most likely water weight. Make sure you are drinking water every day to flush out sodium. As long as your chart has a downward spiral, that is what is important.