EAT-Lancet 2019 Planetary Health Diet + Springmann Nature 2018

Flexitarian Diet: How Often Sometimes Actually Is

Flexitarian eating is the largest plant-forward category in survey data, and arguably the one that delivers the most environmental benefit per practitioner because of how many people are willing to adopt it. The label is loose; this page works through the quantitative versions of flexitarian eating (EAT-Lancet, Mediterranean, semi-vegetarian) and the practical structures that make the shift sustainable.

The short answer. Flexitarian = mostly plants, occasional meat, fish, or dairy as desired. EAT-Lancet Planetary Health Diet allows 14 g red meat per day (about 100 g per week). Halving meat consumption reduces dietary greenhouse footprint by 35 to 45%. The structural trick that works for most people: pick a fixed pattern (Meatless Mondays, weekday vegetarian, vegan-before-6pm) rather than deciding meal by meal.

The terms and their (loose) definitions

The word flexitarian was coined by US dietitian Dawn Jackson Blatner in her 2009 book of the same name. Her original framing was loose: a diet that is mostly vegetarian with some meat included, primarily for health or environmental reasons rather than ethical absolutism. Reducetarian, coined by Brian Kateman around 2014, broadly means "consciously reducing meat consumption without committing to a fixed level." Semi-vegetarian appears in academic cohort studies and is typically operationalised as eating meat less than once per week.

None of these terms has a fixed legal or certifiable definition. There is no Flexitarian Society analogous to the Vegan Society. The Lancet Planetary Health Diet provides the most published quantitative target: 14 g of red meat and 29 g of poultry per day, totalling about 300 g per week of red and white meat combined, plus about 200 g of fish. UK average meat consumption is around 980 g per week per person; US average is closer to 1,400 g. The EAT-Lancet target represents roughly a 70 to 80% reduction from current Western consumption.

For this page, flexitarian will mean the EAT-Lancet target range as a reasonable working number, and the practical advice will scale from there. Eat less meat than you do now is the directionally correct intervention regardless of where you start.

The environmental case in numbers

The Poore and Nemecek 2018 Science meta-analysis (database of 38,700 farms across 119 countries) is the standard reference for food-system greenhouse gas footprints. The published figures per kg of protein delivered: beef 50 kg CO2e, lamb 20 kg, dairy beef 17 kg, cheese 11 kg, pork 8 kg, poultry 6 kg, eggs 4.5 kg, farmed fish 6 kg, wild-caught small fish 2 to 4 kg, tofu 2 kg, legumes 0.8 kg. The dominance of beef in the footprint of a typical Western diet is overwhelming; halving beef intake while keeping everything else constant reduces total food-system emissions by 25 to 35%.

The Springmann et al. 2018 Nature paper modelled global food-system futures and concluded that universal adoption of EAT-Lancet planetary health diet would reduce food-system greenhouse emissions by approximately 50% and would keep land use, freshwater use, and nitrogen and phosphorus flows within planetary boundaries by 2050. No other proposed dietary pattern in the modelling achieves this. The implication is that flexitarian eating at scale is the realistic policy lever for food-system sustainability; full vegan adoption is not a realistic global expectation.

At the individual level, the practical implication is that reducing meat consumption matters more than achieving zero. Cutting beef from 600 g per week to 100 g per week delivers most of the carbon benefit of going fully vegan. This is partly why environmental NGOs and lifestyle medicine groups increasingly frame flexitarian as the realistic ask rather than the moral compromise.

The health evidence

The Adventist Health Study-2 cohort, which separates semi-vegetarians from vegetarians and vegans, has the most useful published data on flexitarian-equivalent diets. Semi-vegetarians (meat less than once weekly in this study) had mortality rates between non-vegetarians and lacto-ovo vegetarians, with hazard ratios consistent with a dose-response relationship between meat consumption and all-cause and cardiovascular mortality.

The Mediterranean diet RCT evidence (PREDIMED trial, n=7,447) showed approximately 30% reduction in cardiovascular events on a Mediterranean diet supplemented with olive oil or nuts. The diet in question is functionally flexitarian: rich in vegetables, legumes, whole grains, olive oil, fish, occasional dairy and poultry, minimal red meat. This is the highest-quality randomised evidence for any plant-forward dietary pattern.

The pragmatic synthesis: flexitarian eating delivers most of the cardiovascular and metabolic benefit of vegetarian eating with less behavioural constraint. The marginal additional benefit of vegan over flexitarian is real but smaller than the flexitarian-over-omnivore step. For people who want to do something but cannot commit to a stricter diet, this is a defensible scientific position.

The structures that work

Structure	How it works	Approximate meat reduction
Meatless Monday	One full meat-free day per week	~14%
Meat for one meal per day	Vegetarian breakfast and lunch, meat at dinner	~50%
Weekday vegetarian	Plant-based Mon to Fri, flexible weekends	~65 to 70%
Vegan before 6pm	Mark Bittman's framework: vegan during day, flexible evening	~50 to 60%
One meat day per week	Six plant-based days, one meat day	~85%
EAT-Lancet target	~100 g red meat and ~200 g poultry per week	~70 to 80% from Western average
Mediterranean	Fish twice weekly, red meat once monthly, regular legumes	~75%
Reducetarian (informal)	Less than current, no fixed target	Variable

The published behaviour-change literature consistently shows that structured patterns work better than open-ended reduction. The cognitive load of deciding meat or no meat at every meal is exhausting; the fixed pattern eliminates the decision. Whichever structure fits your life, pick one and run it for two months before evaluating.

What to put on the flexitarian plate

For plant-based meals, the building blocks are: legumes (lentils, chickpeas, beans), tofu or tempeh, whole grains (brown rice, quinoa, whole-grain pasta, sourdough bread), vegetables, fruit, nuts and seeds, fortified plant milks. The same building blocks as a vegan or vegetarian diet, organised similarly.

For the meat or fish you do eat, prioritise: lower-impact protein per gram (small wild fish, mussels, oysters, chicken over beef where you want meat); higher-welfare sources (RSPCA Assured, Soil Association organic, Marine Stewardship Council); and intentionality (a roast chicken at Sunday lunch with leftovers stretched across the week, rather than fast-food beef burgers).

For dairy and eggs, treat them similarly: moderate intake, prioritise quality and welfare, use plant alternatives (fortified soy milk, vegan cheese) where they work well to free up the dairy budget for things that genuinely matter on your plate. A flexitarian who keeps Italian-style aged Parmesan but switches breakfast milk to fortified soy is making a coherent choice.

Honest framing. Flexitarian is a useful framework precisely because it does not demand absolutism. People who would never sustain veganism often sustain flexitarianism for years. The environmental and health benefits, while individually smaller, are real and aggregate across the much larger population willing to adopt them. This is not a counsel of compromise; it is a recognition that incremental change at scale outperforms heroic change at small scale.

Related diet-type pages

Keep reading

Frequently asked questions about flexitarianism

What counts as flexitarian?

There is no formal numeric definition. The term, coined by dietitian Dawn Jackson Blatner in her 2009 book The Flexitarian Diet, broadly means a primarily plant-based diet with occasional meat, poultry, or fish. Common operational thresholds in surveys and the research literature: under 100 g of meat per day, under 3 meat meals per week, or under 200 g per week. The EAT-Lancet Commission Planetary Health Diet allows about 14 g of red meat per day (around 100 g per week) and 29 g of poultry; this is the most published quantitative target. Reducetarian (Brian Kateman's coinage) overlaps and broadly means reducing meat consumption without specifying a level.

Does flexitarian eating actually help the environment?

Yes, meaningfully. The Poore and Nemecek 2018 Science meta-analysis shows beef at around 50 kg CO2 equivalent per kg of protein. Plant proteins sit at 0.5 to 5 kg CO2e per kg. Halving meat consumption typically reduces dietary greenhouse footprint by 35 to 45% because the meat component dominates the total. A flexitarian eating 100 g of beef per week (instead of the UK average of 600 g) has a dietary footprint comparable to a vegetarian who eats a lot of dairy. The Springmann 2018 Nature paper on planetary boundaries quantified that global adoption of EAT-Lancet planetary health diet would reduce food-system greenhouse emissions by approximately 50%.

Is flexitarian healthier than vegetarian or omnivore?

Health outcomes scale roughly with degree of plant-forward eating. The Adventist Health Study-2 found semi-vegetarian (closely overlapping with flexitarian) had mortality between full vegetarian and omnivore, as expected. Flexitarians retain easy access to B12, iron, omega-3 EPA and DHA, and other nutrients that strict vegans must supplement. The compromise is in the magnitude of cardiovascular and diabetes benefit, which is modest for flexitarian compared to lacto-ovo vegetarian or vegan in cohort data. Flexitarianism is sometimes the practical recommendation for people who would not sustain a stricter diet; an adequate flexitarian diet is better than a poorly adhered vegan one.

What is the EAT-Lancet Planetary Health Diet?

The EAT-Lancet Commission published its Planetary Health Diet in 2019 (Willett W et al., Lancet). The diet was designed to feed an estimated 10 billion people in 2050 within planetary boundaries while meeting human nutritional needs. The daily reference targets: 232 g whole grains, 50 g potatoes and starches, 300 g vegetables, 200 g fruit, 250 g dairy, 14 g red meat, 29 g poultry, 28 g fish, 13 g eggs, 75 g legumes, 50 g nuts, 31 g oils. It is functionally a flexitarian diet with substantial dairy retention. Implementing it would require approximately 50% reduction in global red meat and sugar consumption, doubling of legume and nut intake, and modest dairy reduction in high-consuming countries.

Is flexitarian the same as Mediterranean diet?

Overlapping but not identical. The Mediterranean diet (codified in the PREDIMED trial protocols and the long-standing Mediterranean pyramid) is plant-forward with regular fish, moderate dairy, occasional poultry, limited red meat, and substantial olive oil. It is functionally a flexitarian diet but with specific cuisine and ingredient pattern (olive oil as primary fat, fish as primary animal protein, low to moderate wine). The flexitarian label is broader and does not specify cuisine or fat type. Mediterranean is one valid implementation of flexitarian; East Asian, Nordic, and Latin American flexitarian patterns all exist with different food compositions.

How do I actually start eating flexitarian?

The pragmatic entry point is structural rather than ingredient-focused. Pick a meat-free pattern: Meatless Monday, weekday vegetarian, vegan before 6pm, or weekday vegetarian plus weekend flexibility. The structure makes the change automatic rather than a decision at each meal, which is the failure mode that derails most gradual changes. Stock the kitchen for the plant-based meals (lentils, chickpeas, beans, tofu, tempeh, whole grains, frozen vegetables, fortified plant milk). Use existing favourite recipes with meat removed or swapped (chili with double the beans and no mince; spaghetti with mushroom and lentil sauce instead of beef bolognese). Eat the meat you do eat with attention rather than habit.

Sources cited. Willett W et al. Food in the Anthropocene: the EAT-Lancet Commission on healthy diets from sustainable food systems, Lancet 2019; 393: 447-492; Springmann M et al. Options for keeping the food system within environmental limits, Nature 2018; 562: 519-525; Poore J, Nemecek T. Reducing food's environmental impacts through producers and consumers, Science 2018; 360: 987-992; Estruch R et al. Primary prevention of cardiovascular disease with a Mediterranean diet (PREDIMED), NEJM 2013; 368: 1279-1290; Orlich MJ et al. Vegetarian dietary patterns and mortality in Adventist Health Study 2, JAMA Intern Med 2013; 173: 1230-1238; Blatner DJ. The Flexitarian Diet, McGraw-Hill 2009. All values as of May 2026.