When chia seeds are soaked in water, the soluble fiber forms a thick, gel like mass. When Chia seeds are eaten, the gel-forming reaction occurs in the stomach, forming a barrier between carbohydrates and digestive enzymes, thus slowing the conversion of carbohydrates to sugar during runs. The net result is that Chia seeds are a super slow release energy source, avoiding the usual blood glucose highs and lows.
Chia seeds are exceptionally hydrophilic, able to absorb up to 12 times their weight in water. When in the gut, this means that water loss is minimized and electrolyte balance is maintained for longer.