Doctors and nutrition experts said the regulation’s success or failure may depend on more than just the modest number of calories it might slash from people’s diets. It will hinge on whether the first-in-the-nation rule starts a conversation that changes attitudes toward overeating.

“Ultimately it does come down to culture, and it comes down to taking some first steps,” said Dr. Jeffrey Mechanick, a professor at the Mount Sinai School of Medicine who has studied the effect of government regulation on the obesity epidemic. …

But if the rule is part of a broader social and scientific assault on the dangers of too much sugar, he said, it could be tremendously effective. He likened it to the drumbeat about the dangers of smoking, which took decades to translate into results.