What is water weight, anyway?

When we eat glucose (bread, starches, sugars, etc.) about a day’s worth of energy is placed in short-term storage (like your fridge) as glycogen. Glycogen carries a lot of water. It is believed that one gram of glycogen attaches to 4 grams of water. Glycogen provides the glucose to your body for fuel (when not in ketosis). Since there’s only about 2000 calories available, once it gets low (from exercising and not eating) you’ll “bonk” – run out of energy – and you’ll have to eat some glucose to replenish the fuel supply.

When you go into ketosis, now your fuel source is your body fat, of which there are thousands and thousands of available calories. There is no bonking. Athletes in ketosis can perform for much longer in ketosis than burning glucose. Think of your fat stores as a walk-in freezer (as opposed to the fridge – short-term small-capacity storage).