This paper offers a brief review of economic cycle theories, pointing out the key parameters that describe their dynamic behavior, and proposes a model of asymmetric economic cycles. The model is based on the assumption that economic cycles are non-equilibrium processes characteristic of complex open-ended systems and uses two different see-saw-like sine functions in its construction: an additive version and a multiplicative version. An empirical verification of the model is presented for the GDP cyclic dynamics for several countries and the asymmetries observed on a global scale. For some countries we have also examined the asymmetric behavior for other economic variables, like energy production and unemployment. Conclusions are drawn about the suitability of the model to forecast economic cyclic dynamics.