Intresting, that's what I thought.

What makes it more interesting is that even when you consume fat+protein and get enough calories to sustain your body, and because you don't consume as much carbs your body goes into ketosis and burns fat.

It would seem that you could get a really low body fat because your body still burns the body fat yet has enough energy from protein and fat that it doesn't try to turn your muscle, etc into fuel to keep it alive.

So from that I would start to lean towards thinking that you could get a very low body fat and still be healty. But I'm sure that, as you said, genetics would place a set point as to how low your body would go.

Perhaps I'm missing something here and the outcome I think might happen doesn't match up with what would really happen. Perhaps the part I am missing is what the body does once it gets to the state of "healthy body fat composition". Perhaps at that point ketosis no longer occurs.

The more you think you know...