Aging body means diet is constantly changing

As I age and keep changing I can’t ignore the fact that I have to keep adjusting what I eat. I cannot say zero carbs diet or high protein diet or vegetarian diet. I realize that just because I stay away from pasta, potatoes, bread and rice or can’t eat much of anything at once I have seen big issues. Regardless to how much I work out each day, I have noticed that evenings are getting harder for me. Because I do not tend to eat those foods I keep running out of energy. So I have put some forms of carbs back into my diet just to keep away from eating sweets. I would be so low on sugar I would just start eating anything sweet like a freak stuffing my face and then feeling guilty and then crashing. Today I am making a sweet potato for my dinner it is a good carb and easy to eat, digest and should be able to keep me energized. I went back to the gym after a few week break and it was a hard day, I burned over 1000 calories but could not even finish my entire routine just ran out of gas! In order to keep me going I will have to keep trying different good carb foods and I feel that this will be a never ending task.