> Unfortunately, I'm getting old enough (Late 30s) where IF isn't enough to keep the weight off alone anymore. I guess I need to work out too now.

Not really. exercise is almost irrelevant in terms of energy burnt. I still advise to work out as in strength training combined with functional training (eg balance). building muscle will only get harder with age and it will help a lot with common problems at age especially better balance. More muscle also means more calories burnt when sleeping or watching TV.

What you really need to address is not how much you eat and exercise but what you eat. And here the common advice is usually just poor or even outright harmful, namley low fat. low fat it terrible because it means high carb which means high insulin response. And insulin makes your body store fat and prevent fat from burning.

Second issue is that high fat is too general. You need to go high saturated fat (eg animal fats mostly). mono-unsaturated (olive oil) to an extend is also ok but for sure avoid any highly processed plant oils. polyunsaturated fats (eg. plant oils aka PUFA) are THE cause for arteriosclerosis (full biochemical pathway is pretty much known). The problem is that we feed your animals "crap" especially pigs and chickens but also farmed fish like salmon. So these meats usually also contain too much PUFAs and need to best be avoided. what remains is meat from ruminants that ate gras (beef, sheep/lamb, venison).

What you must avoid under all circumstances is any deep fried food most notably french fries. the repeatedly cooked plant oils used fir frying in most places are unstable and result in toxic products which the deep fried food is drenched in.