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We know that human fetuses whose mom's are nutritionally challenged are born with slower metabolic rates than fetuses whose mom's are not. Human fetuses "can assume" that the resource richness of their post-gestational environment will be similar to their gestational one, with that long period of infant dependence and all. Snakes, though, probably can't "make that assumption."
It seems like it would be advantageous for hatchlings to have some physiological mechanism whereby they could adjust their metabolic rates based on information they receive about the resource richness in their environments (which they would get right after hatching). As a snake, it's beneficial to get as big as possible as fast as possible so you can start breeding. Life history models will tell you that, all other things being equal, decreasing your age at first reproduction is the best thing you can do for your lifetime reproductive success. But when things are really tough and starvation is a serious risk (that is, when juvenile mortality is high, because juveniles are most susceptible to death from starvation because they are small), it behooves an organism to slow down its development--slow and steady at least gets to the starting line, in other words. These models have been used to explain the evolution of protracted vs. rapid development in all kinds of organisms, and have met with a reasonable amount of success, in my opinion. Seems like it could also work within species as well. It would be interesting to experiment with.
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