Flexitarian Diet

The word and its early use

The word flexitarian combines flexible and vegetarian. A 2026 review in the journal Appetite, by Wendler, Sundet and Volden, examined the history of the term. A secondary summary of that review, published by Faunalytics, reports that the exact origin of the term remains unclear and that the earliest documented use the authors found was a 1981 newspaper advertisement for a cooking course, which did not explain what the course involved.

The Appetite paper itself was not opened for this record, so the 1981 date is unconfirmed. The same summary states that the review does not name who coined the term. Some online accounts attribute the word to named individuals, but none of the sources opened for this page names a coiner, and this page does not name one.

From a loose label to a research term

Derbyshire's 2017 review in Frontiers in Nutrition treated flexitarian and semi-vegetarian as terms that are often used interchangeably, and it found that studies defined the diet in different ways. The review called for a formal classification of these diets before the terms could be used reliably in research and recommendations, and it did not present a single historical account of the label.

Forestell's 2018 narrative review in Frontiers in Nutrition notes that meat reduction is discussed in the literature for health and environmental reasons, and that flexitarian eating is often grouped with vegetarianism in public discussion. The sources opened for this record do not trace how the term entered national dietary guidance or food guides, and this page does not describe that history.

Flexitarian and semi-vegetarian

Derbyshire describes a flexitarian or semi-vegetarian diet as one that is mainly vegetarian with occasional meat or fish. Across the studies reviewed, the diet was defined in different ways: some restricted red meat, some restricted fish, and others set frequency limits, such as eating meat at least monthly but less than weekly.

Forestell argues that flexitarians and semi-vegetarians differ from vegans, lacto-ovo vegetarians and omnivores in motivation and behavior, so the label should not be treated as describing one uniform group. Because each study sets its own cutoffs, results from one study cannot be assumed to apply to the same label used in another.

Relation to vegetarian and vegan diets

The Academy of Nutrition and Dietetics uses vegetarian diets to include vegan diets. Its 2016 position paper states that appropriately planned vegetarian and vegan diets are healthful and nutritionally adequate and are appropriate for all stages of the life cycle. The flexitarian diet is usually described as a mostly vegetarian pattern, so it sits near that category rather than being a separate branch of the Vegetarian Diet, though the sources do not define the boundary exactly.

The studies show how much the cutoffs can differ. In a German pilot study, flexitarians ate 50 grams or less of meat and meat products per day. In a New Zealand trial, the flexitarian arm had about three servings of red meat a week on top of an ovo-lacto vegetarian base, and the comparison arm had about three servings of plant-based meat alternatives in place of red meat.

Plant-based and Mediterranean patterns

The sources reviewed for this record do not provide a single agreed definition of a plant-based diet. A 2017 systematic review and meta-analysis by Dinu and colleagues pooled studies of vegetarian and vegan diets, not flexitarian diets, so its findings cannot be read directly as findings about the flexitarian pattern.

The Mediterranean Diet is a separate pattern and is not defined here. Derbyshire states that its literature search excluded related terms such as meat reduction and Mediterranean diets, so the 2017 review does not cover Mediterranean diet research. No Mediterranean diet source was verified for this record, and the page therefore does not compare the outcomes of the two patterns.

What the pattern contains

In the sources reviewed, the flexitarian diet is described by its overall structure rather than by a fixed food list. The core description is a mostly vegetarian pattern with occasional meat or fish, and the amount and type of animal food is set separately by each study rather than by a common standard.

The 2023 New Zealand trial shows one way the structure was set up for research. Both arms followed an ovo-lacto vegetarian base that allowed eggs and dairy but not chicken, pork or fish. The flexitarian arm added about three servings of red meat each week, and the comparison arm had about three servings of plant-based meat alternatives. This was a research protocol and is not presented here as guidance for general use.

Everyday use and measurement

The sources reviewed describe the pattern mainly as a framework for food choice. They do not describe a standard meal plan or clinical protocol for everyday use, and the studies opened for this page do not document how people shop, cook or track their meat intake outside a research setting.

Intake in the flexitarian studies was measured by self-report, diet diaries and short dietary records. Bruns and colleagues note that three-day dietary records are subject to misreporting and may not reflect usual intake, and Gillies and colleagues state that adherence and intake relied on self-reporting. Reported patterns in these studies may therefore differ from usual eating.

Reasons people give for choosing it

In the 2023 New Zealand trial, 35 percent of participants said that trying plant-based eating was a main reason for joining the study. The authors also reported that about 90 percent of the flexitarian group enjoyed and were satisfied with their red meat, compared with 58 percent of the vegetarian group who ate plant-based alternatives. These are reports of participant views within one study, not evidence of health effects.

Forestell reports that health and environmental motives are both discussed in the literature on meat reduction. Her review also notes that flexitarian eating may be linked to restrained eating and weight concerns in some samples, a point taken up under Safety and Suitability.

Health outcomes that reviews associate with the pattern

Derbyshire reports that some studies linked semi-vegetarian patterns with lower body mass index, lower diabetes prevalence or risk, and better glucose and insulin markers. The review describes the metabolic findings as the strongest in its set, while noting that much of the evidence came from one Adventist cohort in the United States and Canada and that the author calls for more research in other populations.

These are associations, and the sources reviewed do not establish that a flexitarian diet causes the differences reported. The sources opened for this page do not support a claim that the flexitarian diet improves any particular condition. The outcomes that were actually studied, and their limits, are described in the Research and Evidence section.

Randomized trials

Derbyshire's 2017 review identified four randomized or clinical trials among its 25 studies. Several were small, with some enrolling about 13 to 22 participants. One six-month trial it describes found that a vegan group lost more weight than a semi-vegetarian group. The review does not describe a trial of flexitarian eating with long-term clinical outcomes.

The most detailed trial opened for this record is Gillies and colleagues' 10-week parallel-group trial in 80 healthy adults aged 18 to 35 in New Zealand, registered as NCT04869163. Participants were randomized in cohabiting pairs and were not blinded to their allocated food. Adherence averaged 96.1 out of 100 in the flexitarian group and 86.7 in the vegetarian group. Positive eating scores rose in both groups. The main outcomes were adherence and eating experience, not disease outcomes. The authors report partial funding from meat industry bodies.

Cohort and cross-sectional studies

In the Adventist Health Study-2 cohort, 73,308 participants were analyzed and followed for a mean of 5.79 years. The adjusted hazard ratio for all-cause mortality was 0.88 for all vegetarians combined compared with nonvegetarians. The semi-vegetarian group had a hazard ratio of 0.92 with a 95 percent confidence interval of 0.75 to 1.13, which does not indicate a statistically significant difference.

A breast cancer analysis from the same cohort, based on 50,404 women and 892 incident cases, found no lower breast cancer risk among all vegetarians combined (hazard ratio 0.97). Vegans showed lower but non-significant point estimates (0.78). The abstract gives no separate estimate for semi-vegetarians.

Pooled evidence on vegetarian patterns

Dinu and colleagues' 2017 systematic review and meta-analysis included 86 cross-sectional and 10 prospective cohort studies of vegetarian and vegan diets. Among the cohort studies, vegetarians had a lower risk of incidence or mortality from ischemic heart disease (relative risk 0.75) and of total cancer incidence (relative risk 0.92). The pooled cohort studies did not show a significant association with all-cause mortality or with total cardiovascular and cerebrovascular disease.

The pooled studies are observational and do not separate flexitarian eating from vegetarian and vegan patterns, so the results are not direct evidence for the flexitarian diet. The vegan subgroup result for total cancer rests on a limited number of studies.

Nutrient adequacy in the flexitarian studies

The 2023 German pilot study compared 32 flexitarians, 33 vegans and 29 omnivores, all healthy adults aged 25 to 45. Flexitarians had lower serum cobalamin than vegans, with a median of 204 picomoles per liter against 300. Their average dietary cobalamin intake was 2.12 micrograms a day, below the 4 microgram reference used in the study. Vitamin D status was lowest among flexitarians. The authors state that deficiencies in cobalamin, vitamin D and iron were common across all diets.

Derbyshire reports that iron deficiency or anemia was more common in semi-vegetarians (38.6 percent) than in non-vegetarians (25.5 percent) in an Australian cohort of young women. An Austrian study reported lower EPA and DHA status in vegans and vegetarians than in omnivores and semi-omnivores. The Bruns pilot study did not report omega-3 status, so omega-3 adequacy in flexitarian eating is not described on this page.

Vitamin B12 and the need for planning

The NIH Office of Dietary Supplements states that vegans, and vegetarians who eat some animal products such as eggs or dairy but not meat, have a higher risk of vitamin B12 deficiency because natural food sources of the vitamin are limited to animal foods. It does not address flexitarian diets directly, so the risk for people who eat meat or fish occasionally is not stated there.

Melina and colleagues' 2016 position paper states that vegans need reliable sources of vitamin B12, such as fortified foods or supplements. The NIH fact sheet notes that deficiency symptoms can take several years to appear and can include fatigue, neurological changes, megaloblastic anemia and palpitations. Because the Bruns pilot found lower cobalamin status in flexitarians than in vegans, the sources do not support assuming that occasional meat or fish removes the need for B12 planning.

Clinical input and care boundaries

The Academy position paper states that appropriately planned vegetarian diets are suitable for all stages of the life cycle, including pregnancy, lactation, infancy, childhood, adolescence and older adulthood. The sources reviewed do not replace individual assessment and do not describe a flexitarian plan for any particular person.

This page does not give personal dietary advice. A registered dietitian or clinician can assess intake and blood markers such as B12, iron and vitamin D, particularly in pregnancy, childhood, older age, or where a condition is already present. Anyone with symptoms of deficiency should seek medical assessment rather than changing the diet alone.

Eating patterns and psychological considerations

Forestell's review argues that flexitarian eating may be more closely tied to restrained eating and weight concerns than other forms of meat avoidance, which could in some people mask maladaptive eating. In a 2012 sample of 240 undergraduate women, semi-vegetarians and flexitarians reported higher dietary restraint than omnivores.