If you are low in energy, your body is less likely to spare that protein for lean mass accrual because it's sensing an energy deficit. So, it's more likely to oxidize that protein or convert it to energy substrate, because, at the end of the day, if we're weighing two things, the first being survival and starvation versus building lean mass, I mean, there's just not the impetus to build a whole lot of lean mass if you're restricted.