Intense Exercise

The more intense the activity, the more important it is to hydrate.

When you begin a hard workout, your body tries to rapidly expand blood plasma volume to handle cooling and nutrient delivery. But because your body holds less fluid in ketosis, this sudden shift can leave you feeling thirsty, sluggish, or flat during the first fifteen minutes of intense exercise.

To fix this early "slump," pre-fill your system by drinking 250–500 ml of water about five minutes before you start.