You should study the topic so you know what your nutritionist is talking about and so you can make decisions about what to eat when the need arises.
The only nutritionist I have studied is Adele Davis. She says your concern about sugar is not as important as what you plan to do with good health in case you happen to acquire it.
She also offers the term "part-smart". The human body needs about forty nutrients, some in balanced amounts, to maintain health. It is good to be concerned about nutrition, but if you are only concerned about one nutrient you are approximately one fortieth part-smart.
These books are old, 1960s era, but they are still the most popular introduction to the field. https://www.amazon.com/s?k=adelle+davis&i=stripbooks&ref=nb_sb_noss_1