How to solve getting fat for no reason - eviltoast

I don’t binge eat, I exercise 3 times a week, or as much as my schedule permits having a 2yold, work, partner and social commitments. I don’t drink. Still I get belly fat now that I am 35+. Wtf? Haas anyone solved this? Did you change diet? Sleep more? Exercise differently? Lower carbs? By how much? Please help me lemmee