Just over 35 years ago, I noticed I was starting to put some unwanted flab on my stomach and ass. I'd already stretched one full pants size, forcing me to buy new clothes. I wasn't happy about it.
I started reducing, reducing, reducing my total intake over the day, to the point where I was eating about the volume of a softball or a little bit bigger. That worked for me: my weight dropped around 25 pounds, and I could wear my old jeans again. I was happier at my earlier size, which reflects in self-confidence.
I've had to adjust it over the years, mostly when I was more active. For 2 years I rode a bicycle *everywhere*, and I had to more than double my food intake to keep my weight up. Same goes with my last job in Phoenix, as I was running up and down long flights of stairs numerous times per day. I walk about 2 or 3 miles every day at the current job, but that's not enough exercise to require a significant boost in calorie intake above my baseline (couch-potato) average intake.