Predators influence prey populations both by consuming individual prey, and by inducing changes in prey behaviour that limit reproduction and survival. Because prey trade‐off predation risk for forageing gains, the magnitude of predators non‐consumptive effects should depend on resource availability. Studies of non‐consumptive effects generally adopt either of two strategies: (i) maintaining a static ration of the preys resources; and (ii) using resource populations that vary dynamically in response to prey behaviour. Contrasting these experimental designs using meta‐analysis, we evaluated whether resource dynamics influence the magnitude of non‐consumptive effects on prey growth, survival, fecundity, population density, forageing rate and habitat use. Predators had a more negative effect on prey demography in dynamic‐ vs. static‐resource experiments. Our results highlight the importance of resource dynamics in mediating the magnitude of non‐consumptive effects of predators on prey, and illustrate the often‐unintended impacts of experimental design on estimates of effect size in ecological interactions.