From the D&C 89
4 Behold, verily, thus saith the Lord unto you: In consequence of evils and designs which do and will exist in the hearts of conspiring men in the last days, I have warned you, and forewarn you, by giving unto you this word of wisdom by revelation—
5 That inasmuch as any man drinketh wine or strong drink among you, behold it is not good, neither meet in the sight of your Father, only in assembling yourselves together to offer up your sacraments before him.
...
8 And again, tobacco is not for the body, neither for the belly, and is not good for man, but is an herb for bruises and all sick cattle, to be used with judgment and skill.
** 9 And again, hot drinks are not for the body or belly. **
12 Yea, flesh also of beasts and of the fowls of the air, I, the Lord, have ordained for the use of man with thanksgiving; nevertheless they are to be used sparingly;
13 And it is pleasing unto me that they should not be used, only in times of winter, or of cold, or famine.
Is there some other official doctrine refining this? Where is it published?
Is hot chocolate not a hot drink? There is indeed no prohibition here about caffeine, only hot drinks like green tea, herbal tea, hot coffee (not iced).