Flexitarianism is generally described as reducing animal-based food intake without removing it completely. However, in spite of its popularity, the concept doesn’t have a formal definition and no specific dietary pattern that includes low amounts of animal products and still meets nutritional needs has been officially established.

To this end, a team of researchers reviewed a total of 86 studies that referenced the flexitarian diet and summarized it as the consumption of dairy, eggs, meat/poultry, and fish/seafood, with each food type being eaten at least once a month but less than once a week. Once they set this definition, they sought to assess how much it aligned with food-based dietary guidelines (FBDGs) from 42 countries, as provided by the Food and Agriculture Organization of the United Nations.

To be included in the study, FBDGs had to be in English, available for download, contain quantitative recommendations for specific diets, and be based on a daily intake of approximately 2,000 kilocalories. While none of these guidelines explicitly named a flexitarian eating style, 14 of them recommended reducing animal products and/or choosing meat and dairy alternatives, 12 described a vegetarian eating pattern, and Sri Lanka included a “semi-vegetarian” eating pattern.

The authors found that the parameters they created for a flexitarian diet aligned with 28 FBDGs, except for dairy products which were often recommended daily. Notably, a few countries such as Australia, Oman, and New Zealand included plant-based dairy in their guidelines. Others, like Georgia and Lebanon, listed food sources of calcium and vitamin D — such as dark green vegetables, nutrient-dense grains, and fortified cereals — as dairy alternatives.

Several guidelines, like those from Jamaica and South Africa, showed feasibility but would require eating more of some animal-based foods and less of others as they grouped all animal products into a single category or recommended multiple daily servings of one animal-based food type. Some FBDGs, including Albania’s, Bangladesh’s, and Ethiopia’s, were found to be incompatible because they recommended several animal products be eaten daily.

Interestingly, newer guidelines such as Zambia’s referenced the global burden of disease study from the 2019 EAT-Lancet report, which suggests eating less animal products for environmental reasons and proposes that diets are flexible to account for cultural traditions and food availability and accessibility.

Ultimately, while most FBDGs didn’t recommend eating less dairy or fish, the study did point to accommodation of flexitarian diets within various national contexts, providing further evidence that reducing intake of animal products may be more manageable for some consumers than strict vegetarian or vegan diets.

The study warned that a lot remains unknown regarding how consumers choose to define a diet low in animal foods, and that sometimes they may choose vegetarian meals without identifying themselves as following any specific dietary pattern. The authors also clarified that isolated efforts to cut out animal products one day per week (e.g., Meatless Mondays) didn’t meet their definition for a flexitarian diet, though they may still contribute to eating less meat overall.

As for limitations, the authors recognized that some FBDGs may have been updated while the study was being conducted and that some subtleties may have been lost when they were translated into English. Additionally, the Food and Agriculture Organization claims that approximately 100 countries have FBDGs, but only 42 met the researchers’ inclusion criteria, meaning the study accounted for less than half of existing guidelines. The authors also searched for the term “flexitarian” in just two databases, which will have missed articles that addressed reduced intake of animal products but excluded this keyword, as well as journals indexed in other databases.

In spite of these limitations, the proposal of a clear definition of flexitarianism may promote a more standardized evaluation of these diets and their role in global nutrition moving forward.