For more than half-century, our understanding of quantum degenerate gases has very much based on the theories of dilute gases which are applicable in the limit of weak scattering. Near resonance ultra-cold gases are currently a platform that experimentalists use to explore exciting physics beyond the dilute limit. This unique opportunity also poses a great challenge to theorists in the community: how to further regularize the formally divergent energy density appearing in the dilute gas theory. In this talk, I am going to report recent progress made on resumation of most divergent contributions to the energy density of Bose gases near resonance. I will also discuss the relation to the Lee-Yang-Huang theory on Bose gases, estimation of the three-body correlations and an onset instability near resonance.