Both my black ratsnake and my cali king have periods where they won't eat even for as long as a month at a time. So far, in the two years I've had these snakes , they have shown two periods of time when they go off feed for a long time. Last year the ratsnake really scared me, at the end of August last year she went off feed for over two months and this year she's doing it again. The cali king went off feed for over a month a bit earlier, throughout most of July. All the snakes I have had long enough to observe them through all the seasons, go off feed for up to a month or several weeks in the wintertime, even though they are kept indoors and all but the garters have supplementary heat under one side of their cages, none were brumated. None showed any noticeable loss of condition during these times either. Incidentally I've also found out that snakes of many different species, kept in different homes under different conditions, all still tend to follow a cycle of being hungry and shedding, they all get hungry at about the same time and all go through shed at about the same time. It would be interesting to find out if other people in different parts of the country also notice this phenomenon, the more information there is and the more sources the info comes from, the more it becomes possible to assess the consistency of this sync among snakes.
The above only applies to snakes other than very young babies however. Baby garters for a reason I have yet to figure out, tend to be difficult to get started feeding. A few will start feeding easily when they get hungry, others will lose condition before showing interest in food, and some will die without ever having eaten anything. Perhaps those who die have some sort of internal birth defects, they often are the babies who from birth on, are the weaker less vigorous babies in a group.