I've been consistently underweight for the last 20 years of my life (BMI 17.9) and this describes my experience. I tend to be on the warm side, am not particula

I've been consistently underweight for the last 20 years of my life (BMI 17.9) and this describes my experience. I tend to be on the warm side, am not particularly active, generally have two or three meals a day and experience no urge to snack. Now that I'm getting towards 40 my "setpoint" weight seems to be creeping up and I may soon cross the line to be consistently on the low-end of "normal." I am still deciding how much energy (if any) I want to devote to keeping where I am now.