In the current study, we sought to replicate the finding that adopting an open/expansive body posture increases subjective feelings of power, while also investigating how these body postures influence the processing of persuasive messages. Two hundred participants were randomly assigned to adopt either an open or a closed body posture while reading either a strong or a weak persuasive message regarding junk food taxation. Afterwards, we measured participants’ attitudes toward junk food, subjective feelings of power, thought confidence, and openness. Results failed to replicate the previously found effect of body posture on subjective feelings of power. Compared to weak messages, strong messages led to more persuasion, higher subjective power, more thought confidence, and more openness. However, body posture did not affect these outcomes. Overall, these findings challenge the idea of a direct, causal relationship between open body postures and power, by showing that power posing effects are not maintained under certain conditions.