Actually, I disagree.
Periods of self-imposed deprivation are spiritually and psychologically restorative. They exist in virtually every major religion, with it being a central tenet of Buddhism. And it's for good reason... our ancestors evolved in a time of scarcity and constant danger. All of this excess and security is weirdly psychologically crippling; it makes us invent adversity in very strange and novel ways because as humans, and indeed as mammals, some adversity is required for us to maintain a healthy psychological profile. Why is mental illness so prevalent in first world industrialized nations, yet seems to fall proportionately as we look toward less developed nations? This self imposed struggle of eating much less and grinding against the weights brings out something very primitive in the human animal. It's something that NEEDS to be expressed for us to function normally and for us to have meaning in our lives. These periods of deprivation and struggle help us to gain perspective and mindfulness when it's all over; the first feast after Ramadan is like the first cheat meal after the diet. Going through that can renew one's zeal and zest for life; it can make us take a step back, realize what it's like to go without, and to find pleasure in the simple and mundane things we'd grown too accustomed to and start to take for granted. And this overall makes us happier and more well adjusted people. And for that reason, yes, there is very much a utilitarian purpose.
Funnily, this increased neurosis and psychological dysfunction when too insulated from danger and too much excess of space, resources, and food manifests in animals as primitive as mice. Divorced from the primal animalistic struggle, they too fall into depression, withdrawn isolation, anhedonia, and existential meaninglessness. See the mouse utopia experiments...
That all being said, I suppose you could do all that and not step on the actual stage. But the prospect of flexing in a manthong in front of a few hundred people will most certainly help with compliance during those times when the diet feels uncomfortable; just like having your religious community collectively participate in lent/ramadan/whatever probably helps with compliance in the same way.