Really basic one..Suger is bad for Adult Adhd?And food?

I have ever heard suger is no-good,but I thought it is like a Myth.

I suddenry realized I am always drinking Coke this 1 or two years,

I don't know if this is the reason,my whole food-life is now mess.and health and life going bad.like burn-out.

I don't have enough power to cook.or go to outside and buy food everyday,so almost depends on

froen foods.

I don't know what is first reason.

When I try to change slowly,what can be first?

(I have to note my kitchen is so small,smaller than bathroom)

And when change slowly,Diet coke or like that is also bad?

I am Japanese and maybe originally people eating very less oily food,but not so diffrent from west in my generation and in my family(lived with till 18 and Now 42).

I realized I know nothing.