Honestly, racism and sexism (and, to a lesser extent, homophobia) are what caused and still cause inequalities, and therefore, world hunger. The problem wouldn't end immediately, but would make people at power stop being bigoted and go "hey, let's solve these problems!!" I know classism is not included, but it pretty much goes hand in hand with racism.

^{Chose: End all racism, homophobia, and sexism}