Watch your urine. If urine is bright or dark yellow, drink more water. If your urine turns dark, stop fasting. Showers at every opportunity. Never pass up a shower when fasting.
Showers help remove toxins released through the skin.
In between showers, dry brush your skin with a rough towel to help exfoliate and remove toxins. Your tongue also excretes, so brush it and your teeth often to remove this layer of toxins. Try to keep yourself warm at all times. If possible, wear layers of extra sets of clothes, towels or sheets. Fasting is a time of slowing down your internal systems, and you should harmonize this in your external movements.