The fat debate

For the last few years, I have been seeing various camps arguing about fats and oil. In response to the widespread rejection of the low-fat craze of the 1990s, we are wrestling over the healthiest fats and oil.  The low-fat craze came from the misguided UDSA Food Pyramid developed in 1992 which resulted in an exponential increase in consumption of refined starches and sugar and reduction in consumption of naturally occurring fats and oils.  During that time the phrase “fat makes you fat” was coined.  However, this phrase is false.  Fat does not make us fat. Sugar and carbs make us fat. The result of the 1990s food trends was the metabolic disease epidemic of the 21st century.

In response to mounting scientific evidence that the food pyramid was dangerous, in 2011, the USDA recommended the Plate Model which reduced starches and increased vegetables but still emphasized low fat refined foods.  Fast forward another decade, in January 2026, the USDA published the new inverted food pyramid. This new model emphasizes minimally processed food, especially protein, fruit, vegetables and unprocessed fat and oil.  In their 90-page document, the authors discussed detailed research to back up their recommendations.  However, they admit that studies about optimal fat and oil consumption is limited and more research is needed.

For now, most nutrition experts agree that the healthiest fats are:

·       Oleic acid: the monounsaturated fat in olive oil and avocado oil.

·       Omega 3 fatty acids: the oil in fatty fish and certain seeds

Oleic acids and omega-3 fatty acids as well as omega-6 fatty acids (also called linoleic acid) are often grouped together and called unsaturated fats. Traditionally, dietary recommendations categorize all types of unsaturated fats as good. However, there is mounting evidence that the truth is more complex.

Saturated fats are solid at body temperature while unsaturated fats are liquid.  As the result of this chemistry, some argue that saturated fat “clog arteries” leading to heart disease and atherosclerosis (narrowing of the arteries).   It is agreed that higher consumption of foods rich in saturated fats (such as butter) raise cholesterol levels.  A 2025 study of over 200,000 people found that those who ate higher amount of butter had higher death and cancer rates compared to those who ate higher amounts of olive, canola, and soybean oils[i].  However, some criticized the study since it grouped olive oil (which is high in oleic acid) with soybean oil (which is high in omega-6 fatty acids). While there is acceptance that omega-3 fatty acid and oleic acid are anti-inflammatory, there is much debate around saturated fat and omega-6 fatty acid.  The question is which one is more inflammatory and disease-promoting: saturated fat or omega-6?

Omega-6 fatty acid, also called linoleic acid, is the most prevalent oil in the American diet. Until the 20th century, the traditional sources of omega-6 for humans were nuts and seeds.  Unfortunately, as the American food supply was industrialized, the amount of linoleic acid in our diets exploded. These oils are extracted from plant material (like soybeans or corn) using industrial chemical solvents.  This contrasts with tradition of extracting oils like olive oil using cold press methods, as done by people living around the Mediterranean for thousands of years.

For decades, medical professionals have looked at linoleic acid as healthy and anti-inflammatory, and, as a result, traditional foods high in saturated fat (like butter) were replaced by processed oils high in linoleic acid (like vegetable oil).  Indeed, linoleic acid is an essential fatty acid that we must get from our diet, but is linoleic acid in a raw walnut the same as linoleic acid in soybean oil produced by chemical solvents?   

The new USDA guideline suggests that too much processed linoleic acid could lead to heart disease. In addition, there is concern that when linoleic acid is exposed to heat, it becomes oxidized, generating potentially harmful compounds. The authors of the new guideline admit that the research is not settled on the subject.  The latest meta-analysis of linoleic acid was published in 2025[ii].  After analyzing 150 studies, their conclusions were mixed showing benefit in some people and harm in others.  Since scientific literature is not definitive, more research is needed.

In the meantime, to promote health and minimize risks, we should consume omega-6 in balance with omega-3. Historically, humans have eaten a diet consisting of equal amounts of omega-6 and omega-3: an omega-6/omega-3 ratio of 1:1. The modern Western diet has a ratio of 20:1 or even as high as 40:1. This imbalanced ratio may be a driver of heart disease, stroke, cancer, and premature death[iii].  However, research is still unclear on the perfect ratio. 

For now, I aim to get back to the historical ratio of 1:1. This can only be achieved by eating less omega-6 (linoleic acid) and more omega-3.  We must consciously and deliberately reduce processed sources of omega-6 in our diet and seek out more sources of omega-3.

As the fat debate rages on, our focus must be on increasing omega 3 fatty acid intake.  The omega 3 fatty acids in fatty fish are called EPA and DHA, which research has shown to improve cardiovascular and neurologic health. The omega 3 fatty acids from plants are called alpha-linolenic acid (ALA) which the body uses to make EPA and DHA.

 Good sources of omega-3 include:

·       Low mercury fatty fish: salmon, anchovies, herring, sardines, Atlantic/Atka mackerel, and trout

·       Marine oil supplements: fish oil, cod liver oil, algae oil

·       Seeds: flaxseed, chai seed, hemp seeds

·       Nuts: walnuts, soybeans

·       Vegetables: seaweed, spinach, Brussel sprouts, mustard greens, purslane

Despite the claims of some internet pundits, eating anything with linoleic acid is not necessarily bad. Balance is key.

The linoleic acid content of common oils is as follows[iv]:

·       Grapeseed (70%)

·       Safflower (70%)

·       Sunflower (68%)

·       Soybean (55%)

·       Corn (54%)

·       Peanut (30%)

·       Canola (21%)

·       Avocado (15%)

·       Olive (10%)

·       Palm (10%)

·       Lard (10%)

·       Tallow (3%)

·       Butter/ghee (2%)

·       Coconut oil (2%)

We should aim to use oils with lower amounts of linoleic acid. I recommend completely avoiding any oils that have more than 50% linoleic acid.  This includes grapeseed oil, safflower oil, sunflower oil, soybean oil, and corn oil. Do not buy those oils. Check labels and avoid ultra processed foods. Any low-cost vegetable oil will contain seed oils extracted with chemical solvents. Avoid them.

Unfortunately, oils with the lowest amount of linoleic acid often have the highest amounts of saturated fats.  When we look at the list above, we can see this to be true since the more solid an oil is, the more saturated fat it has.  Palm oil, lard, tallow, butter, ghee, and coconut oil are high in saturated fats.  Some researchers argue that saturated fat is pro-inflammatory, clogging the arteries. However, others argue the opposite.

The 2026 USDA dietary recommendations emphasize butter, tallow, and full fat dairy over processed oil high in linoleic acid, like grapeseed, corn, and soybean oils. However, before you decide to eat a pound of butter, the new guideline cautions us to keep saturated fat consumption under 10% of daily calories.

Decades of research show that the Mediterranean diet, which is rich in olive oil (oleic acid) and fish (omega-3), produces the largest reduction in heart and metabolic diseases when compared to other diets[v]. This diet contains around 9% saturated fat (generally from dairy and meat) which is a little lower than the 10% recommended in the new UDSA guideline. Currently, the typical American diet has about 12% saturated fat. Therefore, most of us should not look at the new UDSA inverted food pyramid and think we need to eat more butter.  Just the opposite. We need to eat less saturated fat and increase our intake of fatty fish, olive oil, and raw nuts.

I have been puzzled about what to do with canola oil for a decade since it has both positive and negative characteristics. Let’s discuss them. 

The pros of canola oil include:

·       Inexpensive

·      Low linoleic acid (21%) compared to other seed oils

·       High oleic acid (62%)

·       Moderate omega 3 (ALA) (10%)

·       Omega-6 to 3 ratio of 2:1 which is close to optimal ratio is 1:1

 The cons include:

·      Originally called rapeseed oil and used as a lubricant for machinery. The rapeseed was reformulated to be safe for human consumption in the 1970s and renamed canola oil.  This story seems sketchy to some, leading to online debates. Therefore, most canola oil is highly processed and refined using chemical solvents.

Let’s contrast canola oil with olive oil. The pros of olive oil include:

· Thousands of years of usage and cornerstone of Mediterranean diet

·      Low linoleic acid (10%)

·     Very high oleic acid (up to 80% depending on quality)

The cons include:

·    High price for quality cold pressed organic extra virgin olive oil

·   Frequently adulterated with low quality oils

·     Omega-6 to 3 ratio of 10:1 due to it having almost no omega 3.

Avocado oil has similar pros and cons, but it has the added benefit of being stable for high temperature cooking. 

If money is no barrier, the best sources of healthy oils are high quality organic cold pressed olive and avocado oils and low mercury fatty fish. However, for most Americans, cost is a barrier.  The strategy that I take is to balance the two.  I buy the best olive oil, avocado oil, and fatty fish that I can afford, but, at times, I do use organic canola oil for home cooking. It can stretch the budget while providing omega-3.  Due to the consumer push back against chemical solvents, some manufacturers now make organic cold-pressed canola oil, so this option is becoming more widely available.  Lastly, I avoid buying prepared and processed foods with low quality seed oils, instead looking for products made with olive, avocado, or palm oil.  While palm oil is not common in most American kitchens, it has been used in Africa and the Caribbean for centuries. It has the same amount of linoleic acid as olive oil and is relatively inexpensive. Its downside is that is higher in saturate fat (although not as high as coconut oil).

I do not support the argument that we should avoid seed oil all together nor the argument that we should avoid butter completely.  Again, balance is key.  We should eat a variety of whole food containing a balance of omega-6, omega-3, oleic acid, and saturated fats.

References:

[i] Zhang Y, Chadaideh KS, Li Y, et al. Butter and Plant-Based Oils Intake and Mortality. JAMA Intern Med. 2025;185(5):549–560. doi:10.1001/jamainternmed.2025.0205

[ii] Sadeghi, Reza et al. “Dietary and circulating omega-6 fatty acids and their impact on cardiovascular disease, cancer risk, and mortality: a global meta-analysis of 150 cohorts and meta-regression.” Journal of translational medicine vol. 23,1 314. 12 Mar. 2025, doi:10.1186/s12967-025-06336-2

[iii] Zhang, Yuchen et al. “Higher ratio of plasma omega-6/omega-3 fatty acids is associated with greater risk of all-cause, cancer, and cardiovascular mortality: A population-based cohort study in UK Biobank.” eLife vol. 12 RP90132. 5 Apr. 2024, doi:10.7554/eLife.90132

[iv] Mercola, Joseph, and Christopher R D'Adamo. “Linoleic Acid: A Narrative Review of the Effects of Increased Intake in the Standard American Diet and Associations with Chronic Disease.” Nutrients vol. 15,14 3129. 13 Jul. 2023, doi:10.3390/nu15143129

[v] Kiani, Aysha Karim et al. “Modern vision of the Mediterranean diet.” Journal of preventive medicine and hygiene vol. 63,2 Suppl 3 E36-E43. 17 Oct. 2022, doi:10.15167/2421-4248/jpmh2022.63.2S3.2745