Retraining your taste buds is the same in principle as training for anything else.
You learn one new habit at a time.
So to retrain yourself to eat less sugar and to get your sugar from better sources, you start by skipping dessert after dinner.
Or if you can’t imagine dinner without sweet following it, have sliced fruit with chopped nuts.
Have bananas on your breakfast cereal instead of sugars, use berries instead of syrup on pancakes.
With these smaller changes, you’ll notice that you’ve begun to lose your taste for refined sweets like cakes or candy over time.
No cravings or suffering required.