Compounds having the general structure I are provided: X and Y are independently selected from the group consisting of CH2, N, NR9, C═O, C═S, S═O, SO2, S, O, (CR6R7)n, C(═O)—(CR6R7)n, and C(═S)—(CR6R7)n, where n is 1, 2, or 3. W is selected from the group consisting of and L is selected from the group consisting of N, O, S, S═O, SO2, C(O), NC(O), NC(S), OC(O), OC(S), C(NR10), C(NOR10), and a covalent bond. Z1, Z2, and Z3 are independently selected from the group consisting of substituted carbon and nitrogen. Compounds of formula I are agonists of the melanocortin-4 receptor (“MC-4r”) and therefore may have useful properties for controlling diseases related to MC-4r action in humans, such as obesity and type II diabetes.