It's important to note that it's very natural for weight to fluctuate several pounds over the course of a day. In the morning, your stomach is typically emptier due to food being broken down and digested and liquids being eliminated. Once you've eaten, the food in your stomach will add weight to the scale. Additionally, carbohydrate intake increases the water you hold in your tissues, adding weight. When you haven't eating carbs in a while, this effect will be reduced.