Agreed. My entire life up until around age 32 or so I hovered between 95 and 110. Suddenly I skyrocketed within around a year to 170, with no sign of slowdown. I was having to go buy new clothes constantly. I had quit smoking and attributed it to that initially, expecting to have weight gain, until I just kept growing and growing. I was, most definitely not eating more. I was eating the very same as I always had, which is to say pretty lightly. In response to it, I was going to the gym three times a week, sometimes more, doing an entire aerobic and weight training routine each time, but still kept growing and growing.
During a yearly exam, I brought it up to the doctor. She decided to run some more tests, including blood tests and an ultrasound. She diagnosed me with both PCOS and hypothyroidism (which often go hand in hand), which surprised me because I was always a person who fidgeted constantly and was hyper if anything. I asked her why this had rather rapidly occurred as after reading about it, I had learned that this was largely a lifetime condition, but usually diagnosed in 20's/30's. We got to talking about menstruation cycles and such and I had always presented differently, sometimes going for a very long time without one, and of course was infertile, which also had been diagnosed as another reason. I had spoken to a doctors about it during annual female exams as far back as my teens. But way back in those days they didn't even know what it was and simply said that I had a hormone imbalance and was prescribed the birth control pill as a means to control it. They just simply thought it was extra male hormones (also part of PCOS). I also had presented hirsutism, rosacea, and severe acne, also symptoms. I had written off the acne as simply part of my youth. I had never even heard of this thing called PCOS. She told me it was something that they were still learning about. The ultrasound did indeed present numerous ovarian cysts, as well. She proscribed a number of things to me, one of which was a hypothyroid drug. These brought it under control somewhat. I eventually lost all of it, but that was due to a different medical condition.
TL;DR
I was NOT eating any more food, in fact I was eating less because of the weight gain. So no, it does NOT always coincide with overeating.