should I use oil on a plant-based diet?

People go on a plant-based diet for a variety of reasons - ethical, environmental, health, athletic, or otherwise. These are all great reasons! Today, we’re discussing the health reasons not to include oil as part of a whole-food, plant-based diet. Oil can be incredibly difficult to exclude, but I believe there are compelling reasons to count it out: here they are.

caloric vs nutrient density

Oil is the most calorically dense food and one of the least nutrient-dense foods, making it a poor dietary choice. The following graph demonstrates how its caloric density compares to other foods:

This is not to say that you should avoid fats entirely. However, it’s important to be selective about which fats you include in your diet. Oil’s caloric density and relative lack of nutrients leave much to be desired.

heart health and artery function

The endothelium is the inner lining of your blood vessels. It releases hormones that control vascular contraction and relaxation - in other words, the healthier your endothelium, the better your vessels’ ability to respond to increased or decreased blood flow. Endothelial dysfunction precedes the hardening of your arteries, which eventually causes stroke or heart attack. As you can imagine, your diet has a direct impact on the health of your endothelium.

Olive, soybean, and palm oils have been shown to harm endothelial function, regardless of whether the oils are fresh or deep-fried. While high-fiber, high-carbohydrate meals improve endothelial function, a high-fat meal has the opposite effect. In one study, researchers infused fat directly into the bloodstreams of participants (who had no risk factors for heart disease) to observe its effects on endothelial function. Sure enough, an hour later, blood vessels stiffened, becoming less reactive. Though this is an acute effect, imagine a regular onslaught of this kind on your blood vessels. It’s easy to see why oil-laden meals can hurt your cardiovascular health.

A plant-based diet is the only diet that has been shown to reverse heart disease, the United States’ number one killer of both men and women. Of note is that the diet participants consumed in Dr. Caldwell Esselstyn’s groundbreaking study contained 10% fat and strictly no oil.

To date, there is no study that demonstrates reversal of heart disease on a diet that includes oil. The Mediterranean diet has been hailed as the heart patient’s go-to, as research shows that a Mediterranean diet is associated with lower risk of cardiovascular events. However, despite this lowered risk, participants still did suffer cardiovascular events like heart attack and stroke. Compare this result to Dr. Esselstyn’s patients. 12 years after his study concluded, patients who continued to adhere to the diet he recommended suffered “no extension of clinical disease, no coronary events, and no interventions.” In other words, they (patients who were on death’s doorstep before meeting Dr. Esselstyn) were thriving.

I would be remiss to say that oil in the Mediterranean diet is the sole reason that participants in the above study continued to suffer cardiovascular events; after all, the group that consumed nuts in lieu of oil did, too. Perhaps the high percentage of fat consumed (30%, compared with Dr. Esselstyn’s 10%) or potential, unreported dietary noncompliance had something to do with it. However, I believe the totality of evidence indicates that oil is not cardioprotective. And why would it be? Remember that a Mediterranean diet is also rich in whole plant foods. It’s unclear why olive oil is treated as its cornerstone, when perhaps the benefits of a Mediterranean stem from fruits, vegetables, and legumes, true health foods.

oil and diabetes

We’ve known for close to a century that insulin resistance can be induced by high levels of fat in the blood which “[cause] insulin resistance by inhibition of glucose transport.” Practically, this means the more fat you’re consuming, the more insulin resistant you become. What does it mean to be insulin resistant? It means your body must produce more insulin to achieve the same effect: your pancreas works harder to churn out enough insulin to clear your blood of glucose.

While this isn’t an indictment of oil in particular, oil is the most calorically dense fat - just one tablespoon contains 120 calories. Therefore, if you use it regularly, a large percentage of your caloric intake is likely to come from oil, making you less sensitive to insulin.

what about extra virgin olive oil?

Extra virgin olive oil is hailed as a healthier oil because it is less processed, and therefore contains more phytonutrients, antioxidants, and vitamins. However, EVOO still has some of the same pitfalls as other oils: it’s nutrient-poor, highly processed, and calorically dense. Though one study showed that compared to butter it has a neutral effect on endothelial function, another study demonstrates that EVOO hurts endothelial function. Ultimately, if you’re looking to enjoy the health benefits of whatever nutrients are left in EVOO, you’re better off consuming the whole olive.

aren’t fats part of a healthy diet?

Yes! Fatty acids and fat-soluble compounds are unquestionably necessary for your health; your body has essential fatty acid requirements. However, the quality of fat in your diet (like the quality of carbohydrates or protein) matters a lot. Fat-rich whole plants (nuts, seeds, and avocado) are rich in nutrients and have health-promoting effects. Nuts are inversely associated with mortality, and interestingly, though calorically dense, diets that contain nuts don’t appear to increase body weight. When compared with extra virgin olive oil, almonds and walnuts were superior for lowering cholesterol. Seeds are similarly beneficial. Flaxseeds in particular are, in my opinion, a superfood. They’re rich in omega-3 fatty acids, can lower blood pressure in patients with high blood pressure and relieve breast pain in women, and may reduce tumor growth in women with breast cancer.

All of this is to say that you should be selective about which fats you include in your diet. You can choose from a rich array of seeds and nuts for your fat needs, all of which confer a variety of benefits. While I don’t believe that one’s diet should predominantly consist of fat (see my piece on the keto diet), fats have an important place on your plate.

how to cook and bake without oil

Hopefully, armed with this information, you’re ready to make a change to your diet. How, though, can you cook and bake without oil? It’s much more straightforward than you think! Here are some resources you can use.

How to Saute Without Oil
How to Bake Without Oil

If you can afford it, you might also consider purchasing an air fryer. I rarely use one, but if you’re interested in enjoying food with a little crunch, an air fryer is a useful tool.

Hopefully, this piece gave you some clarity on why not to include oil in your diet. Any questions? Leave them below!