Cold atoms are one of example systems interacting through a large scattering length that can be studied by using so called Pionless EFT. They display therefore similar features to nuclear systems but are more easily accessible and controllable in experiments. However, theoretical understanding of this system is challenged by nonperturbative nature of the interaction. Having analytic relations valid for various states of the system are therefore very valuable. In this talk I would like to discuss those relations and show that the Operator Product Expansion technique is a powerful tool to derive those relations. I also discuss recently measured unitary Bose gas that shows an excellent agreement with prediction by the relation.