That is not islamic. I studied Islam. This is a practice done by the shia which makes up about 10% of those who proclaim islam. Somebody invented this practice and somehow it caught on.
In Islam the body is given to you as a trust. You are entrusted to take care of it and nourish it.
Most do not understand what Islam is including some who proclaim to be muslim. I hear people saying Islam means "peace"... nope. Islam doesnt mean peace.
Islam means the sincere submission to the one who created the universe to achieve the state of peace within oneself.
we are all submitting to something at any give time (our own lust, society, our ego, our neighbors, parents expectations, etc... The only way to achieve peace within oneself is to transcend all of that and submit to the creator instead of the creation.
That's Islam. and you also have a complete system of best practices for achieving this state (declaration, 5 daily prayers, fasting, charity and the pilgrimage which make up the pillars).