low, carb or keto might be your answer.
I'm also 60 years old, active and 178 lbs. I lost 5 through covid and it's stayed off. I'm OMAD (one meal a day) just because I'm too lazy to cook 3 meals a day. My resting HR is 50 or less, BP 110 over 60. Minimal carbs, minimal sugar. Strict diets or regimes are a recipe for failure, but a strategy of avoidance works for me. I get bloodwork done a couple times a year and especially pay attention to cholesterol and PSA