Calories in calories out sounds nice but is simplistic.
Combined with proper diet and exercise. It's really that simple. Calories in calories out. There is no magic formulas or potions that allow someone to maintain weight. The problem many people face is discipline. If you have discipline and follow the simple rule you will obtain proper health and weight for your well being.
As we get older the metabolic rate slows down. To compensate you need to have a proper balanced diet e.g. not starving, or just eating a particular kind of food heavy in protein or carbs but good quality balanced nutritional food which is unprocessed combined with a good quality exercise regimen adapted to your current life style.
If you do these two things with discipline over your lifetime you will be in good shape for your age group.
It's as simple as that. All the other stuff like stress, sleep, anxiety are greatly minimized or eliminated by being in good physical health. There is no other solution.
IMO based on scant evidence it sounds like your glycemic levels are fluctuating all over the place. While reading up on the glycemic index will be useful I suggest you seek advise from a trained professional that is knowledable of your specific health and eating patterns. Fact is in weight loss diets do not in the long run work, life style changes are proven to be most effective.
Certified health and nutrition coach
What evidence is that?