Firstly, Santa's body shape is a choice he makes. Because he is the ultimate philanthropist, distributing pressies around the globe, he wants to present himself in the universally accepted role of kindly old fella, so he looks like a universal grandad.
Secondly, the question of the cookies to energy ratio. Now this is where it gets complicated and you might want to sit down and swig that Christmas cheer. HLS (High Level Science) gets easier in proportion to the level of Holiday Happiness imbibed.
Santa converts all of those cookies, mince pies, butter tarts, sherry, milk and eggnog into energy to be able to power his multi-dimensional journey around the planet on a single night. This is because of the little known (amongst the scientific community - very well-known amongst the not-so-scientific one) unit of energy called the IFU. (Imaginary Friend Unit). The IFU enables high calorie snacks in the so-called 'real world', to be converted into easily readily available energy in the IFW (Imaginary Friend World).
IFUs are extremely efficient and allow IFs to slay dragons on our behalf, save distant planets from interstellar wars, and of course, visit 26% of 7 billion people (see what I did there?) in a single night.
So, let's hear it for the IFU! Yay! The not-in-any-way-made-up unit of energy that powers an infinite number of universes from as little as a single cookie.
Now that you know about the IFU, on Christmas Eve, you can leave anything that YOU LIKE for Santa, safe in the knowledge that it will be imbibed and guzzled by someone who will put it to very good use indeed.
Have a safe and happy holiday from all of us at the Burns Bog Conservation Society!