Objectives: This study aimed to identify the predictors of eating more plant-based foods and legumes in terms of previous changes in consumption, habitual frequency of consumption, intention to reduce the amount of meat consumed, and health and environmental identities. Methods: A cross-sectional survey was conducted between June and September 2023 in 881 Polish adults. Based on two self-descriptors, four groups of respondents were identified: no health identity and no environmental identity (nHI-nEI), health identity but no environmental identity (HI-nEI), no health identity but environmental identity (nHI-EI), and both health identity and environmental identity (HI-EI). A logistic regression analysis was used to verify associations between habitual eating of red meat, white meat, and legumes, changes in their intake over the past two years, familiarity with plant-based substitutes for animal products, health, and environmental identity, declared intentions to eat less meat, and the intentions to eat more plant-based food and eat more legumes next year. Results: Individuals were more likely to increase their consumption of plant foods (OR: 1.99, p = 0.001), including legumes (OR: 1.79, p = 0.045), when they represented the HI-EI group, had increased their consumption of legumes in the past two years (OR: 2.91, p = 0.009, and OR: 2.15, p = 0.017, respectively), declared an intention to reduce meat (OR: 8.02, p < 0.001, and OR: 12.08, p < 0.001, respectively), but also occasionally consumed plant-based meat substitutes (OR: 1.76, p = 0.002, and OR: 2.61, p < 0.001, respectively). However, individuals were more likely to increase their consumption of plant foods, but not legumes, if they currently consumed legumes frequently (OR: 1.36, p = 0.009, and OR: 1.22, p = 0.111, respectively) and had previously limited their consumption of red meat (OR: 2.40, p < 0.001, and OR: 1.09, p = 0.717, respectively). Conclusions: The habitual frequency of eating red and white meat did not predict the increased consumption of plant foods in the future. It is equally important to increase people’s awareness of the impact of the food they consume on health and the environment to support their health and pro-environmental motivation for food choices. Public health and sustainability campaigns should develop new methods to reach populations less willing to change.
