Actually theres more to a snake getting fat than simple calories.
As I have mentioned so many times, snakes are not indotherms, as such, there is no apples to apples comparison. Temps and range of temps is very important to reptiles.
For instance, many here seem to assume what they are doing is great. While thats fine, you should really understand, that there is a huge range of good or successful. This range can be measured in terms of various results.
Types of growth is a very good measure of conditions. Individuals growing long and thin(think gangly teenager) is normal. Snakes growing slow in length and fast in girth are at the lower end of normal. Generally speaking, snake growing in girth and not lenght are undermetabolized, that is, do not have a high enough temp range. Their bodies are storing more energy then that are processing into growth. If the temps are lower, all growth and feeding stop. There is a balance between usable temps and usable calories. This balance expresses a huge range of results. Fast growth, slow growth, huge clutches, small clutches, multiclutching, no reproduction at all. And yes, growing fat, or growing long and skinny. Normally bulking out occurs as sexual maturity occurs.
Over metabolized snakes are using more energy then they can store. Think motor running at high RPM's at all times, that uses lots of fuel. The reality is, they use both high and low temps and all inbetween. Unfortunately, many keepers seem to like to tell the snakes what they suppose to do and defend that with all they got. I wonder who is telling the wild ones what to do?
One more thing. Wild snakes are taxed, that is, they have parasites(contributing to more life forms) This taxation is even across the board. Rich snakes(lots of energy comsumed) and poor snakes(lower amount of energy consumed) are taxed with every meal. Of course the poorist go bankrupt and perish. The rich, can affort to be taxed and have no problems paying.
About wild snakes not getting fat, boy howdy they sure can. I have seen exceptional years where the young of the year (here) had great supplys of food, they grew very quickly and very thick(fat) they also became pinheaded(giant bodies, little heads). But no worries, soon taxation caught up to them and so did their head size.
Consider unlike captivity, each year in nature is full of surprises and is different then the last, all you have to do is look at the weather reports. ITs hot, it colder, its not normal, to little rain, to much rain, fires, floods. The funny thing is, these animals have been exposed to this and a million times more. Heck, some were here when continents broke apart, then crashed into eachother.
In otherwords, in nature, it tends to work itself out. In captivity it may not. Remember nature has extremes and parasites(taxation) to control temporary abundances of calories. Cheers
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??? I do admit, they're both very well fed obviously. Try finding six foot kings in the wild - Good luck!!! I havn't found one yet (found hundreds of kings, but only 5 foot and below)!
I do know of a captive in St. Pete that may be the biggest king I've seen. It must be over 6' and is definitely a Pinellas animal. Maybe even wc, I have to ask.