A semi-vegetarian is someone who eats a primarily plant-based diet but still includes meat, poultry, or fish occasionally. There’s no single official definition, but most research defines it as eating meat at least once a month but no more than once a week. The term is often used interchangeably with “flexitarian,” a blend of “flexible” and “vegetarian,” and it describes a growing group of people sometimes called “meat reducers.”
How Much Meat Counts as Semi-Vegetarian
Because there’s no governing body that certifies someone as semi-vegetarian, researchers have drawn the line in slightly different places. The most commonly used definition in large health studies comes from the Adventist Health Study-2, which classified semi-vegetarians as people who ate red meat and poultry at least once per month but less than once per week. Eggs and dairy were consumed freely. Other researchers have defined it as eating red meat, poultry, or fish no more than once a week total.
In practical terms, this typically translates to a few servings of meat per week at most. One clinical trial defined its flexitarian group as eating roughly 390 grams (about 14 ounces) of cooked red meat per week on top of an otherwise vegetarian diet. That amount falls within the World Cancer Research Fund’s recommendation of no more than 500 grams of cooked red meat weekly. Some semi-vegetarians eat even less, reserving meat for one or two meals a week and building the rest of their plates around vegetables, grains, legumes, and dairy.
How It Differs From Other Diets
The semi-vegetarian label sits in a middle space between full vegetarianism and standard omnivore eating. Here’s how it compares to the most common dietary patterns:
- Omnivore: Eats meat more than once per week, with no restrictions on type or frequency.
- Semi-vegetarian (flexitarian): Eats a mostly plant-based diet with occasional meat, poultry, and fish, typically less than once a week.
- Pescatarian: Excludes red meat and poultry entirely but eats fish and seafood alongside dairy and eggs.
- Lacto-ovo vegetarian: Excludes all meat, poultry, and fish. Eats dairy and eggs.
- Vegan: Excludes all animal products, including dairy, eggs, and honey.
The key distinction is that semi-vegetarians don’t eliminate any category of animal food. They simply eat much less of it. A pescatarian who eats salmon three times a week consumes more animal protein than many semi-vegetarians, but a pescatarian still draws a hard line at red meat and poultry. Semi-vegetarians draw no hard lines; they just shift the balance.
Health Benefits Compared to Regular Meat Eaters
Even modest reductions in meat intake appear to move the needle on several health markers. In the Adventist Health Study-2, which followed over 73,000 people, semi-vegetarians had about a 24% lower risk of developing type 2 diabetes compared to nonvegetarians, after adjusting for age, activity level, BMI, and other factors. That’s a smaller reduction than what vegans (49% lower risk) or lacto-ovo vegetarians (46% lower risk) experienced, but it’s meaningful for a dietary shift that doesn’t require giving anything up entirely.
Body weight follows a similar gradient. A cross-sectional study found that flexitarians had a median BMI of 22.0, compared to 25.0 for omnivores. That three-point difference places the average flexitarian squarely in the normal weight range, while the average omnivore sits right at the threshold of overweight. Vegans in the same study landed at 23.0, which is notable: the flexitarians actually had slightly lower BMIs than the vegans, though the difference wasn’t statistically significant.
For overall mortality, the picture is more nuanced. The Adventist study found semi-vegetarians had a death rate of about 6.16 per 1,000 person-years, with a hazard ratio of 0.92 compared to nonvegetarians. That suggests an 8% lower mortality risk, but the confidence interval crossed 1.0, meaning the difference could be due to chance. Stricter vegetarian patterns showed stronger and more statistically reliable mortality benefits.
Nutrients to Watch
One advantage semi-vegetarians have over full vegetarians and vegans is that occasional meat and fish intake helps cover some of the nutrients that plant-heavy diets tend to run low on. But “helps” doesn’t mean “solves.” A systematic review in the journal Nutrients identified a surprisingly long list of nutrients that semi-vegetarians may still fall short on: vitamin B12, vitamin D, iron (especially in women), zinc, iodine, calcium, and omega-3 fatty acids from fish (EPA and DHA).
Vitamin B12 is the one to pay closest attention to. Meat eaters average about 5.6 micrograms per day, while vegetarians average around 2.1. Semi-vegetarians fall somewhere between those numbers depending on how often they eat animal foods. Since B12 is found almost exclusively in animal products, someone who eats meat only a few times a month could still come up short. Vitamin D intake tends to be below recommended levels across all dietary patterns, not just semi-vegetarian ones, so that’s less of a diet-specific concern and more of a population-wide gap.
Iron and zinc present a subtler challenge. Plant-based sources of both minerals are less easily absorbed by the body than animal sources. The Institute of Medicine estimates that people eating mostly plant-based diets need about 1.8 times more iron than standard recommendations to compensate. For women, who already have higher iron needs, this can become a real gap if meat meals are infrequent.
Environmental Reasons People Choose It
For many semi-vegetarians, health is only part of the motivation. Reducing meat consumption is one of the most effective individual-level changes a person can make to lower their environmental footprint. Vegan diets produce roughly 50% fewer greenhouse gas emissions than typical omnivore diets, and lacto-ovo vegetarian diets about 35% fewer. Semi-vegetarian diets fall somewhere below that 35% mark, but still represent a significant reduction compared to eating meat daily.
This is one reason the flexitarian approach has gained traction with people who find full vegetarianism unsustainable or unappealing. The logic is simple: if millions of people eat somewhat less meat, the aggregate environmental impact may be greater than a smaller number of people going fully vegan.
What a Typical Week Looks Like
There’s no single meal plan that defines semi-vegetarianism, which is part of its appeal. Most days look vegetarian: oatmeal with fruit for breakfast, a grain bowl with beans and roasted vegetables for lunch, pasta with marinara for dinner. One or two days a week might include grilled chicken, a serving of fish, or a small portion of beef in a stir-fry. Eggs and dairy typically appear freely throughout the week.
Some people structure it deliberately, designating certain days or meals as their “meat meals.” Others simply eat meat when it’s available or appealing and skip it otherwise. Research on dietary adherence suggests the flexibility itself is the diet’s biggest advantage. In a 10-week trial comparing a flexitarian diet to a fully vegetarian one, participants following the flexitarian plan found it easier to maintain. The lack of rigid rules reduces the psychological friction that causes people to abandon more restrictive diets.
If you’re considering shifting toward semi-vegetarianism, the transition can be as gradual as you want. Swapping a few meat-based dinners each week for bean soups, lentil dishes, or tofu stir-fries is enough to qualify by most research definitions. The health and environmental benefits scale with how much you reduce, so even small changes move you in the right direction.