This sounds like the point I was getting at a few months ago!
A little over a year ago, I had divorced, and was able to eat more of what my body needed, than what was given to me. The ex-wife had given me only so much for monthly allowance, and none of it covered my appetite. And, when I would come home in the evening after work, she barely gave me enough to eat for dinner! (Sometimes I was starving in the middle of the night!!) But, because of that, I had kept an average weight of 160 lbs (for a height of about 5'10"), which was borderline underweight in my opinion!
After the divorce, I could finally eat what I wanted, and as much as I wanted, but ended up gaining about 5 kg (ab. 10 lbs?) in a three month time! The jeans got a little snug, but my slacks for work, got too snug for comfort, and I had to stop wearing them. With the meters in Japan that can also check the body fat ratio, it didn't indicate any "fat" increase, but my weight gain was obvious. Even now, I once saw a body fat ratio of 26%, but just last week, it went to 24% when I measured (yet my weight was unchanged), but no change in body weight! I'm able to extend my stomach, and when I do, I look about 8 months due, or something like that (My wife cracks up when I do that!), though I sometimes feel like that just after having too much to eat, or something.
I've always had trouble with push-ups, but less trouble doing sit-ups! Part of my reason for Aikido, is that it doesn't need "as much" strength in the upper body than say, Judo, so I found it much easier to become proficient in. (at least until my injury!)
I'd be happy just to get my strength, natural weight (maybe 165lbs.?) and longevity back.