I was certainly thin in the 80s. Probably because I was in my 20s, single, exercised a lot, and was a nicotine addict. I used to be a runner. I think I got down to about 167 at one time at my fittest in maybe 1984. Stayed pretty fit by running, bicycling, some weightlifting through about age 35, so early 90s. Switched to a sedentary job and gave up nicotine. It has been a battle ever since.
I am now back down to about the same weight I was in the mid-90s, so only one more decade of time-reversal to go.