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The Pros and Cons of Plant and Animal Fats: What Research Says


For years, experts hotly contested whether fat in the diet was good or bad. But now that we know a healthy diet includes plenty of fat to help the body absorb fat-soluble vitamins, cushion the organs, provide energy, and even reduce inflammation, there’s another debate raging.    This particular nutritional tug-of-war questions which are better, plant or animal fat sources. Especially if you’re following a keto or other low-carb, high-fat diet, you may have found yourself deep in this discussion, wondering exactly how to compose your daily intake of fats.

People on a vegan diet may champion plant-based fats, while those with a carnivore approach argue that animal sources are best. The truth probably lies somewhere in the middle. We’re breaking it down to explain the pros and cons of plant and animal fats so you can build your menu plan with the right combination of both.

Benefits of Animal Fats

Name a farm animal and it probably provides some form of fat! Fat can be extracted from various parts of pigs, cows, sheep, goats, chickens, ducks, and geese. If you’ve ever traveled overseas, you may have even tried fats derived from more exciting animals like buffalo or camels. The more you consume lipids from animals, the larger your fatty vocabulary may be. (Fun fact: did you know “schmaltz” is the official name for rendered chicken fat?)

Not all animal fats are created equal, of course, but they generally share some common features. Here’s a look at the good a bit of butter, lard, tallow, suet, or schmaltz could do you.

Found in Foods That Contain More Protein

Animal foods don’t only contain fat. By definition, they also have protein. When you consume animal fat in its whole, original form, such as in a cut of steak or chicken breast, you’ll also reap the benefits of consuming far more protein than you would in most plant-based foods. Even non-meat items like yogurt, cheese, and butter contain varying amounts of this crucial muscle-building macro.

Animal protein is considered a “complete” protein, meaning it contains all the essential amino acids your body can’t make on its own and must get from food. (Most plant-based proteins can’t compete with this nutritional claim to fame.) Including plenty of animal-based fats from whole foods not only boosts your intake of protein in general, but complete protein specifically.

Animal foods high in protein will also leave you feeling satisfied – even more so than foods with fat alone.[*] In fact, some research indicates a high-protein diet may even help you achieve more significant weight loss.[*]

Some Animal Foods Contain Healthy Unsaturated Fats

When it comes to the “good” unsaturated fats that promote heart and brain health, vegetarian options like olive oil and avocados tend to get top billing (while animal fats are often lambasted for their saturated fat content). But plant foods don’t own the market on cardio- and neuroprotective fats. Multiple animal sources of fat boast mono- and polyunsaturated fats of their own.

Salmon rises to the top of the list of seafood with the most heart-healthy omega-3 fatty acids – but if these pink swimmers are outside your budget (or your taste preference), you can opt for tuna, mackerel, sardines, or herring for large doses of omega-3s.

Dairy foods like whole milk, yogurt, and grass-fed butter also provide sizable doses of monounsaturated fats. And here’s a surprise: even poultry and red meat contain small amounts of these beneficial lipids.

May Add More Flavor

We’ll be honest: there’s nothing quite as lip-smacking as the flavor of bacon. And anyone who’s ever tasted the magic of foods fried in duck fat can attest to their savory deliciousness.

Although plant-based fats and oils have unique flavors of their own, many people find animal fats offer richer, more complex notes in cooking. That’s because refined oils like olive oil have had many of their volatile fatty acids and aroma compounds stripped away. Even unrefined oils can lose their flavoring acids and aroma compounds when exposed to heat.[*]

Unrefined animal fats, on the other hand, create new flavor compounds when they interact with heat, ultimately making for a complex-tasting finished product. For this reason, some foods may simply taste better or richer with animal-based fats.

May Provide Brain and Nervous System Benefits

The human brain is made up mostly of fat – so it only makes sense that we need to eat fat to maintain a healthy brain. One question research has raised, however, is whether plant or animal sources benefit our brains more.

The omega-3 fatty acid known as DHA (docosahexaenoic acid) is particularly renowned for its neurological benefits. This fat helps develop infants’ brains in utero, as well as builds brain structure and synthesizes neurotransmitters throughout the lifespan.[*] Since the highest-DHA foods happen to be animal products like mackerel, salmon, and herring, this could be a good enough reason to include them in your diet.

Drawbacks of Animal Fats

Inconclusive Relationship Between Saturated Fat and Heart Disease

While some animal foods contain the mono- and polyunsaturated fats well known to bolster health, many of them are also high in saturated fat. At one time, it seemed cut and dried that saturated fat was a cause of heart disease – but more recent investigation has called this health precept into serious question.

A growing body of research points to a more complicated relationship between saturated fat and heart disease. In fact, several studies have failed to find any correlation between eating foods high in this fat and the likelihood of heart problems.[*][*] The last several years have seen a gradual shift of expert opinion from “saturated fat definitely clogs your arteries” to “maybe saturated fat isn’t as bad as we thought.”

In a nutshell, the jury is still out on the exact effects of this type of fat on heart disease (and whether processed versus whole sources of sat fat might play a role). For now, it’s best to moderate your intake of animal products high in saturated fat, balancing them with plenty of unsaturated fats as well.

Possible Link to Type 2 Diabetes

The relationship between large categories of foods and chronic disease is usually a tricky one – and this holds true for a link between animal fat and type 2 diabetes as well as heart disease. Some research has indicated that an increased intake of saturated and animal fats could mean higher risk of developing type 2 diabetes, [*] but other studies have found no relationship between eating animal fat and the likelihood of this disease.[*]

At the moment, there’s no scientific consensus that eating animal fats leads to type 2 diabetes, but future research may shed more light on a possible connection (or lack thereof) between the two.

More Likely to Require Refrigeration

This drawback is more of a nuisance than a health concern, but many sources of animal-based fat do require refrigeration to extend their shelf life. Granted, this isn’t true of lard and tallow (and even butter can be left at room temperature for hours or days without going rancid), but it’s recommended to keep most fresh animal products in colder temps.

Benefits of Plant Fats

There’s a reason the plant-based movement has gained so much popularity in recent years. Getting more plants in your diet has some tremendous benefits – some of which come from the fats they contain.

Reduced Risk of Heart Attack and Stroke

For most of us, part of the motivation to eat a healthy diet is to minimize our chances of developing concerning health conditions like heart disease and stroke. This is where a diet higher in plant foods could reap major dividends.

According to 2019 research that followed over 90,000 subjects for an average of 22 years, people had lower cardiovascular disease risk when they ate more plant-based monounsaturated fat in place of processed carbs and saturated and trans fats.[*]

Found in Foods with Other Important Nutrients

Whereas animal foods provide fat in tandem with plenty of protein, plant foods offer up their fat content with other nutrients. This includes antioxidants like vitamin E in olive oil, carotenoids in avocados, and fiber in nuts and seeds.

Including more plant-based fats could mean you’ll get a greater variety of nutrients for a more balanced diet. (And if you’re concerned you’re not getting enough vitamins and minerals from your diet, consider these 14 best supplements.)

Associated with Lower Risk of Mortality

Eat veggie fats and live longer? It’s possible! One study of over 63,000 subjects found that people who included more plant fats in their diets had lower total mortality (AKA were less likely to die of any health cause) than people who ate more animal fats.[*] This was especially true when plant fats replaced saturated fats, refined carbs, and trans fats.

Drawbacks of Plant Fats

May Oxidize More Quickly Than Animal Fats

Oxidation is the chemical process by which oils can become rancid or even toxic. Unfortunately, many plant-based oils oxidize fairly easily, especially when exposed to too much light or cooked at high temperatures.

Animal-based fats like lard and butter, on the other hand, are far more chemically stable. Even when used at high temperatures, their saturated fats (which keep them solid at room temp) are more difficult to break down.

As a result of these differences in properties, it’s best to steer clear of most plant-based oils (with the possible exception of avocado oil or non-virgin coconut oil, which are more heat-stable) in high-heat applications.

And more concerningly, research suggests that heat-processed oils like canola oil and other “vegetable oils” (which are plant-based but don’t actually contain vegetable oils) contain free radicals that can damage cells in your body and may harm your health[*]. The same is true of fried foods prepared with plant-based fats, too.

Plant Foods May Not Be as Satiating

As mentioned above, many animal fats are naturally “packaged” with protein, as is true with meats, seafood items, and dairy products. But plant foods that contain fats, however high in vitamins and minerals, don’t tend to be paired with as much protein. Nuts, seeds, and soy products, for example, contain moderate (but not high) amounts of protein. For this reason, they may not be as satiating as animal foods.

If you choose to use plant oils in your cooking, be sure to pair them with a source of protein or complex carbohydrates to ensure they fill you up.

Some Foods with Plant Fats May Be More Highly Processed

The inexpensiveness and versatility of plant fats like corn oil and soybean oil lend themselves well to mass production – which is why you’ll see them on the ingredient labels of many highly processed foods. Packaged pastries, ice creams, salad dressings, and snack foods often feature low-quality vegetable oils.

If you’re working on eating a healthier diet, you’ll want to avoid these foods. Despite what research may say about plant fats promoting longevity and heart health, consuming them through foods like ice cream and donuts doesn’t mean better health.

Plant Fats vs. Animal Fats on Keto

All this info may be well and good for the average eater, you may think, but what about if you’re on the keto diet? Does it matter whether you load up on fats from burgers and salmon versus olives and avocados?

The short answer is no. To achieve ketosis, the type of fat you choose won’t matter as long as you’re consuming a high enough percentage of it. That said, since both sources have health benefits, it’s smart to include a mix of the two.

Of course, if you’re on a vegan keto diet (which is difficult to manage and definitely not for everyone), you’ll want to stick solely to plant-based fats. And if you’ve gone keto-Paleo, you’ll naturally incline toward fats from more animal sources (along with plenty of nuts and seeds). For everyone else in between, though, both types of fat have their place on a keto diet.

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Plant and Animal Fats to Include on Keto

Try crafting your keto menu plan with a variety of plant and animal fats, such as any of the following.

Plant Fats to Include on Keto

  • MCT oils
  • Olive oil
  • Coconuts and coconut oil or butter
  • Seeds like flax seeds, chia seeds, hemp seeds, and pumpkin seeds
  • Nuts like almonds, pecans, walnuts, cashews, and macadamia nuts
  • Seed and nut butters
  • Avocados and avocado oil

Animal Fats to Include on Keto

  • Fatty fish like salmon, tuna, mackerel, and herring
  • Ground beef, steak, and other cuts of beef
  • Full-fat dairy like grass-fed butter, ghee, yogurt, and milk
  • Eggs
  • Chicken and turkey

Takeaway: Plant Fats vs. Animal Fats

Like most debates about diet, the question of whether to eat more fat from plants or animals doesn’t come with perfectly black and white answers. Since new research is always emerging to highlight the benefits and drawbacks of both sources, it’s smart to hedge your bets by eating a diverse diet that includes multiple sources of fats. Avoid ultra-processed fats whenever you can, choosing fats from whole foods for a delicious variety of meals and snacks.

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