Social media influencers have become increasingly prominent in advertising, and many play a role in shaping body image perceptions. This research proposes that disclosing influencers' body size through hashtags can help mitigate issues related to body image that have historically arisen from viewer exposure to idealized body images in advertising while promoting informed consumer decisions. Across two experiments, we investigate how body size hashtags and the type of motivation appealed to (intrinsic vs. extrinsic) influence social comparison, perceptions of influencer attractiveness, and purchase intention. Results reveal that individuals engage in more social comparisons when viewing an ad in which a larger-sized influencer and an appeal to intrinsic motivations are used. We also identify social comparisons and perceived attractiveness as key mechanisms linking the effects of body size hashtags and motivation appeals to purchase intention. Managerial and societal implications are discussed.