A: Your body is made up of a lot of water and your total body water will fluctuate a lot throughout the day. If you exercise a lot, haven’t hydrated after a night asleep or have had alcohol then your total body water might be lower than normal. Hydrating before the test won’t show an instant increase in the TBW but over time will help to increase it. Also, as your total body fat increases, you might find a drop in your total body water. You will find that as your body fat drops, your total body water should start to increase.
Try to stay hydrated every day, and not just some days. Try to not allow yourself get thirsty and monitor your urine colour. It shouldn’t be too dark, the best is a pale straw colour. The healthy TBW % for women is at least 45% and for men is at least 50%.