To wit, regardless of these fables, or, rather, because of them, the most reasonable conclusion regarding Jesus and where he may or may not have been is that he is a mythical character, not a historical personage who trotted the globe.
It has nothing to do with losing any weight except the weight on your soul. But God honors the person who denies her own bodily desires for a time and devotes herself to prayer and fasting.
Other tales depict Jesus "walking the Americas" or bopping about Glastonbury, England, with his "uncle," Joseph of Arimathea.
Not all of these tales can be true, obviously, unless Jesus is polymorphous and phantasmagoric, a perspective that in reality represents that of the mythologist or mythicist.
Because of this, they lack a sound foundation to reconcile the differences.
A spiritual fast is undertaken to lose something of this world and gain something in the next.