The ‘Vegetarian Protein = Less Nourishing’ Intuition: When the Choice of Vegetarian Protein Increases Calorie Consumption: An Abstract

Abstract

This research tests an unexplored bias that consumers instinctively infer vegetarian proteins to be less nourishing than equivalent meat proteins. Four studies show that consumers purchase more proteins, calories, carbohydrates, and fat when exposed to vegetarian proteins. This research is important for marketers and policymakers, as this bias can contribute to the worldwide obesity epidemic. Previous research explored barriers to a complete vegetarian diet (Lea & Worsley, 2003; Pohjolainen et al., 2015); however, it did not investigate potential biases consumers might have of vegetarian proteins nor the behavioral consequences of selecting vegetarian proteins in place of meat. With 4 studies, this research empirically demonstrates that consumers erroneously judge vegetarian proteins as less nourishing, which leads to the assumption that vegetarian proteins have fewer calories and thus increased consumption. Study 1 aimed to establish the existence of the “vegetarian proteins = less nourishing” intuition. 256 MTurkers participated in a single-factor (vegetarian vs. meat) between-subjects experiment. Participants read a scenario describing a lunch choice between two options (vegetarian/meat). Participants then saw either the vegetarian or meat dish and evaluated it. The vegetarian dish was considered less nourishing (Mmeat = 5.84; Mvegetarian = 5.28, p < 0.001) and less caloric (Mmeat = 5.24; Mvegetarian = 4.10, p < 0.001) than its meat equivalent. Calorie inferences were mediated by nourishing perceptions (β = 0.1893, SE = 0.0706, CI 95%: 0.0733; 0.3441). Study 2 tested if providing explicit protein content could reduce this bias. 208 MTurkers answered this 2(vegetarian/meat) × 2(protein information: present/absent) between-subjects experiment. Participants saw a (vegetarian/meat) meal and evaluated it. We manipulate protein information by adding (or not) the description ‘this portion contains 20g of protein’. Results revealed no main effect of protein information (p = 0.21), nor a interaction (p = 0.985), but a significant main effect of protein type on nourishing perceptions (Mmeat = 5.72; Mvegetarian = 4.92, p < 0.001). Study 3 demonstrated the bias impact on consumption. 157 students read a scenario describing a daily lunch choice (either vegetarian or meatballs, randomly assigned) and then indicated the portion size they would have. Participants selected a marginally larger portion size in the vegetarian condition (Mmeat = 6.61; Mvegetarian = 7.3, p = 0.056). Study 4 measured the total calories served when consumers have vegetarian (meat) protein. 121 students read a scenario in which they received either meat or vegetarian protein. Next, they could order a side dish, a dessert, and/or a drink. Each category contained two healthy and two unhealthy options. We estimated the amounts of calories, fat, and carbohydrates of the complimentary items chosen. Participants selected food items that resulted in higher calorie content (Mmeat = 349.6; Mvegetarian = 428.8, p = 0.045), carbohydrates (Mmeat = 48.2; Mvegetarian = 57.8, p = 0.046) and fat (Mmeat = 14.78; Mvegetarian = 19.54, p = 0.076) in the vegetarian condition. This research provides relevant insights for policymakers facing the challenge of promoting the reduction of meat consumption.