What does ‘flexitarian’ really mean? New research maps the gray zone between omnivore and vegetarian

As global interest in plant-forward eating grows, a new study published in Nutrients has attempted to bring much-needed clarity to one of the most ambiguous dietary labels in modern nutrition: the 'flexitarian' diet. The paper, authored by researchers from the US Department of Agriculture and the University of North Dakota, seeks to define what constitutes a flexitarian eating pattern – and assess whether existing national dietary guidelines (FBDGs) support this approach.

'Flexitarianism' typically refers to a flexible, mostly plant-based diet that includes small amounts of animal products. But as the authors note, the term lacks consistent, quantifiable criteria. Drawing from 86 peer-reviewed studies, they synthesized a working definition: a diet that includes meat, fish, eggs, or dairy at least once a month but less than once per week.

This pragmatic approach, often described as 'vegetarian-ish', appears to be gaining popularity. While just 2% of Americans identify as vegan and 3% as vegetarian, 5% say they follow a flexitarian diet, according to 2024 survey data from the International Food Information Council. Health benefits, enjoyment of plant-based foods, and concerns about animal welfare were the most common motivators.

“Despite the growing interest in plant-based diets, few people adopt fully restrictive vegetarian or vegan patterns,” the authors write. “Flexitarian diets may be more acceptable to a larger portion of the population.”

The authors conducted systematic literature reviews using PubMed and Scopus to identify how flexitarian diets are described across the scientific literature. They found wide variation in terminology, including 'semi-vegetarian', 'reducetarian', 'meat-reducer', and 'casual vegetarian'. Most definitions involved occasional meat consumption, ranging from a few times per month to once or twice a week. Notably, these diets do not eliminate entire categories of animal-derived foods but aim to reduce their frequency and quantity.

To allow comparison with national dietary guidance, the researchers used a simple definition: diets in which dairy, eggs, meat or poultry, and fish or seafood are each consumed at least once per month but less than once per week. This summary definition allowed them to assess whether existing FBDGs could accommodate flexitarian eating patterns.

The team reviewed 42 national or regional FBDGs available in English, downloaded from the Food and Agriculture Organization (FAO) website. These guidelines came from countries including Germany, India, New Zealand, Kenya, Saudi Arabia, and the USA.

While none of the guidelines used the word “flexitarian,” only one – Sri Lanka – explicitly referred to a 'semi-vegetarian' diet. However, a substantial number included guidance for vegetarian diets, and several recommended reducing consumption of meat or animal products, or choosing plant-based alternatives to meat and dairy.

Several countries had guidance that aligned closely with the flexitarian framework. Germany recommends limiting meat to one serving per week and suggests a diet that is three-quarters plant-based. Spain caps meat intake at three servings per week and promotes a Mediterranean-style diet with limited red meat. The US Dietary Guidelines for Americans (2020-2025) allow for meat or poultry roughly four times per week and explicitly include fortified soy milk and soy yogurt as part of the dairy group.

In contrast, several countries including Albania, Bangladesh, and Ethiopia recommend daily intake of animal-source foods such as meat or dairy, making adherence to a flexitarian diet less feasible within those frameworks.

Dairy remains a sticking point. While many countries’ guidelines encourage reducing red meat, relatively few promote reducing dairy, and some group dairy alongside other animal foods without providing alternatives. Countries like Australia, New Zealand, Oman, and the Nordic countries stand out for recognizing fortified plant-based beverages as acceptable substitutes.

The analysis comes amid broader shifts in how national governments and public health agencies incorporate sustainability into food policy. Since 2010, more countries have started acknowledging environmental impacts in dietary guidance, with 37 now doing so according to a 2022 review cited in the study.

The flexitarian model represents a middle ground that balances nutritional adequacy with environmental and ethical considerations. For public health authorities, understanding this dietary pattern could improve how they communicate with consumers who are reducing animal products without eliminating them.

Yet despite increasing consumer uptake, flexitarianism remains under-defined and underrepresented in formal dietary policy. The authors suggest that clearer language and more flexible dietary modeling could help bridge this gap.

“Some version of a flexitarian dietary pattern reduced in meat or poultry foods aligns with dietary guidance in several countries,” the study concludes. “However, few countries have guidance that allows for a flexitarian dietary pattern with limited dairy intake.”

While this study helps outline parameters for what qualifies as a flexitarian diet, the researchers caution that flexibility is inherent to the concept. Attempts to pin down rigid definitions could undercut the appeal of the approach, which is, by nature, adaptable.

Still, the authors argue that having some shared reference points could enhance dietary assessments, improve public health messaging, and support consumers looking to reduce animal product intake.

'Flexitarian' may be a moving target – but this research helps bring it into clearer view.