You've named all the things to stay slim and healthy:
Carbs are good, don't be carb phobic, rice, potato, bread all good
Sugar is ok
Whole grains over rated, processed white bread for example easy to digest.
Low fat, they use a little oil to cook.No keto or other fad, not obsessed by eating protein.
They should eat more veg and fiber though hence they have a high incidence of bowel cancer.
When i meet slim older ladies i ask how they stay slim, they are careful what they eat, not too much