Given a Banach space (X,parallel to . parallel to), we study the connection between uniformly convex funcitons f : X -> R bounded above by parallel to . parallel to(p) and the exictence of norms on X with moduli of convexity of power type. In particular, we show that there exists a uniformly convex function f : X -> R bounded above by parallel to . parallel to(p) if and only if X admits an equivalent norm with modulus of convexity of power type 2