Sometimes when I am out and about, I cannot manage as much fat as I would normally eat at home.

I find that when I don't have enough, my circulation suffers and I get cold hands and feet, even when the weather is warm.

Does anyone else have this problem. My circulation has always been excellent but lack of fat = chilliness.

Actually, I doubt it's related to consumption of energy, and more based on your metabolism. Body temperature is a sign of your metabolic state.