In 2010, three meat and cheese loving Americans decided to go vegan for 6 weeks. The film Vegucated follows their journey as they discover the horrors of the food industry and the many benefits a vegan diet can bring you. When the three people were followed up in 2013, one person was vegetarian and the other two were still vegan.
The consistency principle states that when a stand is taken, there is a natural tendency to behave in ways that are consistent with that stand, especially when the commitment is public. In a study by Deutsch and Gerard (1955) students were asked to estimate lengths of lines. Some students were asked to commit themselves publicly to their decisions, while others were asked to commit privately and the final group were not asked to commit at all. The students who had publicly recorded their initial estimate were much less likely to shift from their position later on. Public commitments tend to be lasting commitments.
As these people claimed on film that they were turning vegan for 6 weeks, this level of commitment may have influenced them to stay away from meat in the long-term.
Deutsch, M., & H. B. Gerard. (1955). A study of normative and informational social
influences upon individual judgment. Journal of Abnormal and Social Psychology,