While health communicators often study strategic health messages, investigations of how visual message elements complement or inhibit persuasive efforts are sparse in the literature. Visual juxtapositions, which refer to one visual presentation featuring two images placed next to each other, are one such visual element. In the context of improving public communication efforts related to promoting healthy dietary choices, we use visual persuasion theory and exemplification theory to test whether different visual juxtapositions influence message recipients' expectations to share message content and reduce their consumption of unhealthy products (i.e., sugary drinks and salty foods). We carried out two studies, each a two-wave, longitudinal randomized experiment, to test for direct effects and assess the potential for indirect or delayed associations of visual persuasion appeals using visual juxtapositions. We consistently observed that a similarity visual juxtaposition evoked higher levels of surprise and expectations to share message content than a comparison juxtaposition or control condition immediately following message exposure; however, visual juxtapositions had no direct effects on unhealthy consumption expectations immediately following exposure or one-week following exposure. Levels of surprise were associated with both intended outcomes in the short-term (increased message sharing expectations) and unintended outcomes in the longer-term (increased consumption expectations). Overall, the study offers insights into the effects and associations of visual juxtapositions on message processing and persuasion outcomes, as well as raises questions about how to apply visual persuasion concepts and improve theorizing related to visual persuasion in health communication contexts.