Is an oil-free diet healthier? What are the arguments for and against eliminating oil from your diet?
Some popular diet trends recommend eliminating all forms of oil from your diet—including oils that are often promoted as healthful, such as olive oil. Is an oil-free diet healthier?
Nutrition Diva listener Joy recently asked about this in a Facebook discussion. “What do you think about the idea that oil is unhealthy and should be avoided?,” she wrote. “I've noticed that some plant-based recipe blogs I like highlight their oil-free recipes. And a doctor told me I should work on eliminating ALL oil (not fats, just oil) from my diet. If you haven't done a podcast on this topic, please think about covering it!”
Your wish is my command, Joy. Let’s take a closer look at some of the arguments against oil.
Is Oil Unhealthy Because it is Processed?
Oils are generally extracted from whole foods. Olive oil is pressed from whole olives, corn oil is pressed from corn, and so on. In the process of extracting the fat, valuable nutrients (such as fiber) are left behind. Oil is also much more calorie dense than the whole foods it is pressed from.
This is similar to arguments I’ve made against fruit juice. When we squeeze an orange, we remove the fiber and end up with a more concentrated source of sugar and calories. We can also drink a glass of juice much more quickly than we can eat an orange, and this can lead to overconsumption.
One difference here is that no-one is going to drink a glass of olive oil instead of eating a few olives.
Olive oil is most commonly used to dress a salad or roast vegetables. Does adding oil to your salad add calories? You bet. Does it make those vegetables less nutritious? Not at all. In fact, adding oil to your salad helps you absorb more of the nutrients in those vegetables. And if it makes those vegetables more appealing and palatable, so that you eat more of them (and less of other things), it’s a win all the way around.
This seems to be the case for Cheryl, who posted, “Since I stopped limiting my olive oil years ago, I've eaten way more vegetables—because they taste great with oil and not as great without it.”
As for valuable nutrients being left behind, many of the most beneficial nutrients in olives, nuts, seeds, and avocados—such as omega-3 fatty acids, phytosterols, vitamin E, and polyphenols—are fat soluble. These nutrients are not only present in the oil, but they are often in more concentrated amounts than you’d get from eating the whole foods.
Can Consuming Oil Lead to Weight Gain?
One website promoting oil-free diets claims that “Oil...has more calories per gram than any other food...and without any fiber or water in it, oil lacks the bulk to convey to your senses how many calories you have eaten; this virtually guarantees you will consume more calories at the meal than you need.”
It’s absolutely true that oil is a concentrated source of calories but I don’t buy the argument that including oil in your diet will inevitably lead you to consume too many calories and gain weight.
As I explained in my episodes on satiety and satiation, water and fiber add volume to foods, which helps fill the stomach. That’s one of the reasons that I encourage you to eat vegetables whenever you can. But fat can help you eat less through other mechanisms—by stimulating the release of gastrointestinal hormones that reduce the desire to eat, and slowing down the absorption of carbohydrates from your meal, which leads to steadier blood sugar levels.
Combining vegetables (with their high water and fiber content) with healthy fats such as those found in olive oil can be a winning combination in terms of nutrition, taste, and appetite control.