Given that elves are the most avid lovers of sweets, do any of Gaia’s other peoples love sweets almost as much as elves do? What about less?
Elves are stereotyped for loving sweets, and there is a real reason behind this: elves are inefficient spell-casters. This means they can cast more potent spells with less effort, but as a result, their arcane energy drains faster than other species.
Arcane energy is directly tied to calorie intake. And when these excess calories run out, the spells resort to eating the elf's fat and organs. This is why elves struggle to gain weight, but have no trouble losing it.
Excessive spellcasting can seriously damage an elf's organs and cause a condition called "arcane burnout". If severe enough, it can be fatal. This condition isn't exclusive to elves--all magic-using peoples can experience it--elves are just more susceptible to it.
What does this have to do with sweets, you ask? Sugar and carbs are very dense in calories. Elves (and all magic-users) rely on excess calories to cast spells. So, loading up on sweets is the most efficient way to fill up the ol' magic tank.
Fae bodies process sugar more gracefully than commoners and gaians. They don't experience the same tooth-rotting, pancreas-destroying consequences that other peoples do. As a result, they can eat cakes and candy for breakfast, lunch, and dinner every single day of their lives and remain healthy.
Fae are stereotyped for "loving" sweets because they eat a lot of sugar. In reality, their crazy sugar consumption is more about efficiency than love. (Although many fae do indeed have a sweet tooth, just like anyone else!)
Commoners can't use magic, but gaians can if they choose to. However, gaian bodies don't process sugar with the same grace that fae do, so they can't get away with cramming sweets down their throat all the time without suffering health problems.
This makes gaians less efficient spellcasters than fae, because they have to keep a balanced diet while also making sure to have enough excess calories to cast spells.
There are many gaian mages who decide to eat like crap to get ahead in their magic studies, and this may work for a while. But it's only a matter of time before this diet catches up with them, and if it continues for too long they will be in rough shape.
This is one of the main reasons fae have an edge over gaians in spellcasting.
