What’s a plant-based diet? Vegan, vegetarian, pescatarian & flexitarian

7-min read • There are a few types of plant-based diets: what are they and which is the right one for you?


This article is part of the Vegan Beacon, a series detailing the what, why and how of being a vegan.

Getting this out right off the bat: a plant-based diet and a vegan diet are not the same thing.

Yes, a vegan diet is a plant-based diet, but it is just one variation of plant-based diets. There are others that allow some room for animal foods, albeit in relatively limited amounts.

From Terra Environment Dictionary, a plant-based diet is defined as:

A diet that consists mostly or entirely of foods derived from plants, with few to no animal products.

The good news is that if you’re looking to get on a plant-based diet, you don’t have to commit straight to a fully vegan one with absolutely zero animal foods.

comparison chart of types of plant-based diets
Note that even those indicated by checkmarks are reduced consumption.

There are currently four main types of plant-based diets: vegan, vegetarian, pescatarian and flexitarian. Read on to learn about the differences and see which is the right one for you.

Vegan

What’s a vegan diet?

A vegan diet is simply a diet that consists of food derived purely from plant sources, and none from animal sources. This means zero meat, seafood, eggs, dairy and honey, including animal-derived additives such as chicken stock, pork broth and the like.

Why a vegan diet?

The reasons for going on a vegan diet are usually as part of becoming a vegan and adopting the lifestyle of one. However, there are also instances where one goes on a vegan diet as just a dietary choice—independent of the veganism principles and lifestyle—which in this case is typically for health reasons.

Vegetarian

What’s a vegetarian diet?

A vegetarian diet, like a vegan one, excludes meat and seafood. The main difference is that vegetarians can include animal products that are not parts of their bodies, such as egg, milk and honey, in their diets. To better draw the lines across different types of vegetarian diets, the more technical terms are:

  • ovo-lacto-vegetarian: a diet that excludes meat and seafood, but includes eggs and dairy. This is what most people mean by “vegetarian”.
  • ovo-vegetarian: a diet that excludes meat, seafood and dairy, but includes eggs.
  • lacto-vegetarian: a diet that excludes meat, seafood and eggs, but includes dairy.

Note: ovo- is a prefix relating to egg (think ovary, ovulation), lacto- is a prefix relating to milk (think lactose, lactation).

Why a vegetarian diet?

For some who want to eventually go vegan, they may choose to adopt a vegetarian diet first as a way of easing themselves into the dietary change. The exclusion of red and processed meats also means that health benefits can be gained from becoming a vegetarian.

Vegetarian diets feature in a number of religions, particularly ones originating from Asia, such as Buddhism, Hinduism and Jainism. These religions promote ethical ideals of non-violence and mercy to all living beings, and so advocate against killing animals for food. Fun fact: some of these religious practices even advocate against eating roots, tubers and other vegetables (e.g. potato, garlic, onion) that involve uprooting (and thus killing) the plant.

As you don’t have to kill chickens for their eggs or cows for their milk, such animal products are thus historically considered acceptable to consume. However, these practices were established in olden times when animals were personally raised and cared for by farmers. Since the advent of industrial farming, the production of eggs and dairy do result in chicks and calves being culled as unwanted byproducts, not to mention the inhumane treatment that layer hens and dairy cows suffer from birth to premature death.

Pescatarian

What’s a pescatarian diet?

Also spelled as pescetarian, a pescatarian diet differ from vegan and vegetarian ones in that pescatarians include seafood in their diets. Like vegetarians, pescatarians abstain from meat, and may include eggs and dairy in their diets. The same variants thus apply, e.g. ovo-lacto-pescatarian.

Why a pescatarian diet?

Common reasons for a pescatarian diet include health (abstinence from meat), ethics and environment.

A pescatarian diet can be considered a good compromise between the above reasons, and nutrition (and taste). Nutrition in a plant-based diet is often lacking in vitamin B12 (the only nutrient that cannot be naturally acquired by a vegan), vitamin D, omega-3 fatty acids, iodine and selenium—all of which can be obtained by consuming fish like tuna and salmon.

The fishing industry also does not produce anywhere near as much carbon emissions as land-based agriculture does. However, problems of overfishing, bycatch and damage caused to marine habitats remain.

Mediterranean diet

countries bordering the mediterranean sea
The Mediterranean diet originated from the eating habits of countries bordering the Mediterranean Sea

A pescatarian diet may also be adopted for cultural reasons, in the form of the Mediterranean diet. The Mediterranean diet came about from the traditional eating habits of people in countries bordering the Mediterranean Sea, such as Italy and Greece—whom observers noted to be exceptionally healthy. The diet is high in olive oil, legumes, grains, cereals fruits, vegetables; moderately high in fish; moderate in dairy and wine; and low in non-fish meat.

The Mediterranean diet has since been developed and recommended by health experts, and was even voted as the best diet for three consecutive years between 2018 and 2020.

Flexitarian

What’s a flexitarian diet?

A portmanteau combining flexible and vegetarian, a flexitarian diet is a semi-vegetarian diet that encourages mostly plant-based foods while allowing small amounts of meat and other animal products.

There are no clear rules or definitions to flexitarianism—the point is simply to minimise meat and animal products. Many of you may already be on a flexitarian diet without even knowing it.

Here are some common variants of a flexitarian diet:

  • Meals-of-the-day: fully plant-based but have a “cheat meal” each day, e.g. no meat and seafood for breakfast and lunch, but allowing them for dinner
  • Days-of-the-week: similar to meals-of-the-day, but spanning over the course of the week, e.g. Meatless Monday, weekday vegan
  • Social omnivore: fully plant-based when eating alone or at home, but allowing for animal products when dining in social settings

Why a flexitarian diet?

Again, health, ethics and environment.

A flexitarian diet is often adopted by people who are making a transition into more restrictive plant-based diets. Similar with addictions like smoking and drinking, it might be more constructive in the long run to ease out the habit (in this case, consuming animal products) rather than quit cold turkey. The abrupt change might not be successfully sustained, and the miserable experience will heighten your personal barrier from trying again.

Which plant-based diet is right for you?

While we have identified four different categories of plant-based diets, just remember that they are, after all, just labels.

Labels are useful because they are widely understood and helps you communicate your dietary preferences more easily in social settings—nobody wants to say “I am on a eat-fish-on-Sunday-but-otherwise-vegan diet”.

Beyond that, however, it’s your personal journey and entirely up to you how you want to shape your diet. I’ve been on a ovo-pescatarian diet since June 2019—and in the next step of my transition towards an eventual vegan diet, I’m considering to drop shrimp and tuna completely. Just think about how I’m supposed to describe that diet to people.

Customising your own plant-based diet

You may feel a little lost if you were to customise your own meal plan, away from the standard plant-based diets covered above (with the exception of flexitarian, which is non-standard). Here are some guidelines, depending on what your motivations are for a plant-based diet:

Health

The first food you should cut from your diet for health reasons is red meat and processed meat. It’s also a good idea to moderate your intake of seafood, as they contain amounts of heavy metals like mercury and arsenic.

Ethics

If your greatest concern about eating animal products is animal rights and welfare, you should look to cut anything that is produced by industrial farms. This means most meat, poultry, dairy and egg products.

If you want to still enjoy these as parts of your meals, look out for organic, grass-fed or pasture-raised labels, and purchase from independent farms and at farmers’ markets instead if you can.

As for seafood, opt for wild-caught fish rather than farmed ones.

Environment

First off the list: beef and cheese.

carbon emissions per serving of different food types
Comparison chart of pounds of carbon dioxide equivalents emitted per food serving | Source: Center of Sustainable Systems, University of Michigan

Just go down the chart as you progress. You may be wondering: why is there such a huge disparity in carbon emissions between milk and cheese, even though cheese is made from milk? It takes one kilogram of milk to produce one kilogram of cheese. (A minor note: serving sizes are different as well.)

Seafood isn’t on the list, as carbon emissions are largely from fuel use by boat engines, and vary widely. Also, fisheries do not require farmland or care of livestock, and thus have a much smaller carbon footprint. Of course, environmental issues like population decline are still causes for concern.


At the end of the day, the focus shouldn’t be on what type of diet you follow or identify with. Instead, hone in on what more you can do for your health, animals and the environment.

Delving further into this: it’s also more important to take a big stride in significantly reducing your consumption of animal products, than it is to take the final, relatively smaller step in eliminating them completely.

Of course it’d be ideal if 100 percent of the world were vegan—but while we’re collectively moving towards a healthier, more compassionate, and greener future, the world would be a better place if we had, say, 20 percent of the global population be flexitarians, than if we had only 1 percent be vegans.

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