Could the Scale Lie?
Don't be discouraged if your weight fluctuates day by day. Shifts in water weight, constipation, and even the food you just ate can cause the daily changes reflected on the scale. To avoid confusion and disappointment, weigh yourself only once a week. Let how much healthier you feel and how your clothes are fitting be your "scale."
These daily weight changes are particularly common during Phase 1, when your body is adjusting to the new way of eating. You may also notice that you weigh more immediately after a meal. This is due to the actual weight of the food and not to any fat weight you've gained. Remember that it takes time for your body to digest food, and it can take a couple of days for weight loss or weight gain to register on the scale.