I'm 5'7", was 120 when I started college. Got up to 147 at my peak around age 55. I kicked up my workouts a notch, started watching what I ate, and now I try to stay at 121-122 to keep my BMI at 19 or above. (Yes, I DID see the previous post on BMI.) This morning I was 120. Problem is that I'm trying to keep my a1c down without meds (jumped from 5.5 to 5.8 over 6 months, just measured last week) and my triglycerides are high. So, anything I want to add to my diet to gain a bit should not be heavy in sugar or animal fats. That excludes most of the yummy stuff!
And yes, I'm happy to have this "problem". I feel very good at this weight but I have a little osteopenia and want to make sure it doesn't get worse.