It's loss of water weight. Low carb dieters shed initial water weight very quickly.
If I understand correctly, it's because some carbs are stored in the liver compounded with water as glycogen. When you start low carbing, the glycogen starts being used and the extra water is released (via your kidneys).
I started carb reduction without reading much about it and experienced the classic effects: quick weight loss, dehydration, muscle cramping, sudden loss of appetite. Maintaining hydration and electrolyte balance is important when adjusting your body towards using less carbs.
If I understand correctly, it's because some carbs are stored in the liver compounded with water as glycogen. When you start low carbing, the glycogen starts being used and the extra water is released (via your kidneys).
I started carb reduction without reading much about it and experienced the classic effects: quick weight loss, dehydration, muscle cramping, sudden loss of appetite. Maintaining hydration and electrolyte balance is important when adjusting your body towards using less carbs.