Your Guide to Fats: Which Vegetable Oils Are Bad?

On the cover of health magazines in the 80s, 90s and even into the 2000s, you would have seen a lot of hullabaloo about how fat was Public Enemy #1 and it was making us all, well…fat. They demonized fat for obesity rates, rise in cardiovascular diseases, and other chronic conditions. The low-fat craze told us how we needed to avoid fat at all costs; then a plethora of reduced fat processed foods hit the store shelves in response to consumer demand.   

Then in 2002 appeared a seminal article written by the science writer, Gary Taubes, “What if it was a big fat lie?” – which started to turn the tide on the evils of fat. Our collective nutrition consciousness has decided that the scientific evidence is not pointing to fat as Health’s Most Wanted. In reality, fat is an essential part of our diet as humans. Fats help fuel our mitochondria, absorb vitamins and minerals, and keep us satiated after a meal. Did you know that our brains are even made up of 60% fat! And oils are some of the best sources of fats that can support our overall health.

However, understanding which oils are healthy and which should be written off of your eating plan is important in creating a balanced diet. In this blog, we’ve reviewed the different types of fat, and which oils to choose or avoid next time you’re at the grocery store or cooking a meal.

Types of Fats

There are three main types of fat: saturated fat, unsaturated fat, and trans fats.

Saturated fats mean that the fat molecule—also called a triglyceride—is completely “saturated” with hydrogen molecules. In the picture below, you’ll see how saturated fat is full of H’s (hydrogens); this allows saturated fats to stack on top of each other and build up easily, causing things like plaque buildup in your arteries. Some of you may remember restaurants transitioning from saturated fat (lard, tallow) to all vegetable oils (corn, soybean) in an attempt to switch to a healthier source. How ironic this is – we all know that saturated fats like lard are less processed and much more stable for cooking or frying. The moral of this lesson is that overall, you only need saturated fats in moderation for health. If I could find a restaurant that serves fried chicken cooked in lard again, I would love to go splurge!

Unsaturated fats have one or more double bonds (=) where the molecule is not saturated with hydrogens. This creates a kink in what would otherwise be a continuous, stackable chain. These kinks created by the unsaturated areas keeps the fat from building up as saturated fat does; as such, unsaturated fats are generally a healthier choice than saturated!

Trans fats: Do you remember when Crisco shortening was a main ingredient in many of the recipes then? Trans fats are formed when unsaturated fats are refined in a process called partial hydrogenation; these are fake oils and should be avoided. Consumption of trans fats has been linked to increases in heart attacks, inflammation in the body, and blood cholesterol levels. The city of New York leading the way with the first ban on trans fats in restaurants has demonstrated improved public health and lower rates of hearts attacks and strokes. Way to go Big Apple!  

Healthy Oils

1. Olive Oil

Olive oil is high in monounsaturated fat, which has been linked to lowering LDL cholesterol and promoting heart health. Olive oil which hasn’t been processed with chemicals is called virgin olive oil, and the highest grade of virgin olive oil is called extra virgin olive oil.

Christine Palumbo, a registered dietician, explains, “[Extra-virgin olive oil] contains more than 30 different phenolic compounds, a group of phytochemicals that include many with anti-inflammatory and blood vessel-expanding actions.” Olive oil is perhaps the most common choice for healthy oil, and it’s a clear example of fat that will actually help your heart health. Unfortunately, not all olive oil is actually olive oil – there are many blends and fakes out there. When the world’s production of olive oil does NOT match what is being sold as ‘olive oil’, there’s plenty of reason for suspicion. We will highlight what to look for in olive oil in a later blog.

2. Avocado Oil

Avocado oil is also teeming with monounsaturated fats and all the health benefits that come with them. This oil is especially unique because it retains its nutritional content at high and low temperatures; others, like olive oil, have a low smoke point, so the oil begins to break down sooner while cooking. Avocado oil is a great, neutral tasting option with high health benefits. I tend to use avocado oil for stir-frying as it’s more heat stable than olive oil. 

3. Sesame Oil

Sesame oil has naturally occurring polyunsaturated fats, which are also helpful for heart health! Research has reported that sesame oil has anti-inflammatory effects while also providing antioxidant support. Together, these properties help fight heart disease and plaque buildup in the arteries. Sesame oil has been a staple in Asian cooking for centuries, and is a heart-healthy addition to your own pantry. Keep in mind that sesame oil should only be used as a topping or a seasoning oil as it’s not heat stable for long-term cooking or frying.

Oils to Eat In Moderation or Avoid

Although we need fat in our diet for optimal health, there are some oils that we should only consume in moderation or avoid like the plague.  

1. Coconut Oil – Moderation

Coconut oil’s reputation has been up and down in recent years: some dieticians used to claim it was the best fat for your health because of its medium-chain-triglycerides, while others staunchly recommend against it for its high saturated fat content.

The research on coconut oil is mixed, with some studies pointing to it raising your HDL cholesterol (the good stuff), while other research shows that coconut oil might raise your LDL cholesterol (the artery-clogging bad stuff).

Because of its mixed reviews and high saturated fat content, the Cleveland Clinic and many others recommend you use coconut oil in moderation. I like coconut oil when making popcorn but due to the strong flavor, it’s usually reserved for a snack or a dessert dish.

2. Palm Oil – Moderation

Check the label of any jar of peanut butter and you’ll likely find palm oil listed; it’s a popular ingredient in many processed foods. With roughly a half and half makeup of saturated and unsaturated fats, palm oil isn’t as bad as some other options, as long as you’re not eating a lot of it. To me, the bigger issue is that extracting palm oil has been shown to have negative effects on the environment; the World Wildlife Fund reports that it increases deforestation and unethical working conditions. Opt for all natural peanut butter and avoid palm oil next time you’re at the grocery store. Read labels carefully because palm oil is hidden in a lot of snacks and otherwise healthy foods.

3. Vegetable Oils – Avoid

Vegetable oils include corn oil, sunflower oil, soy oil, safflower oil, grapeseed oil, cottonseed oil, rice bran oil, and rapeseed (Canola) oil.

New York Times best selling author and family physician Cate Shanahan, MD, notes how the high level of refinement needed for these oils in combination with their high content of polyunsaturated fats (PUFAs) makes them a poor choice. The refinement process makes the PUFAs more unstable, less nutrient dense, and more likely to lead to inflammation in the body.

Shanahan recommends opting for oils that are less refined and closer to whole foods, whether that might be a cold-pressed olive oil or avocado oil as mentioned earlier.

I love how fats give me energy throughout the day without needing to raid the fridge every several hours. It also gives me mental clarity. It’s necessary to have fat in your diet, and when you opt for healthy oils like olive, avocado, and sesame oil, your body and brain will thank you.  It may be time to clean out your cupboard and re-prioritize your vegetable oil shelf!