re: Almost 40 and I’m officially fat

What is the best diet and exercise regime? Keto? Atkins? IF?
Answer: The one that you will stick to!

What I recommend:

1.If you have not already done so, cut out all alcohol.

2.Eliminate sugar.

Those two alone are a GREAT way to start. If you do no nothing else, those two alone should shed some pounds.

3. Walk. Start out just walking for 20-30 minutes, in your neighborhood, place of choice, with a spouse/friend/pet, etc.

Do that for awhile and see how you respond. THEN I would look into the "next level", creating a daily caloric deficit with your macros, and adding some resistance training to your exercise regime.

If you slash calories hard right now AND add a bunch of resistance work, you will most likely not be able to sustain it and probably quit. Each week or two, you then create another caloric deficit, maybe 200-300 calories, something reasonable, and create it via diet, exercise, or a combo of both.

This approach will also allow you to retain muscle better while losing fat. You DO already have some muscle and you want to keep it for many reasons.