One of the greatest nutritional myths ever perpetuated is that saturated fat is the root of all dietary evil (spoiler: it’s not). It started in 1977, when the Senate Select Committee on Nutrition and Human Needs published “Dietary Goals for the United States” and recommended that Americans avoid saturated fat and eat more carbohydrates. The committee’s recommendations were based on observational studies by Ancel Keys, Ph.D., a professor of physiology at the University of Minnesota, who embraced the idea that saturated fat raised levels of cholesterol, which then lead to atherosclerosis. But while Keys was promoting his own hypothesis, other scientists were questioning its validity, and in fact, multiple researchers argued that sugar and carbohydrates were the cause of heart disease, not saturated fat.1
Despite pushback from other researchers, the government moved forward with its recommendations, leading generations of Americans to avoid saturated fat and build their diets around chemically altered trans fats, refined carbohydrates, and sugar. For decades, nutrition experts and the media told us to limit or avoid eating all fatty foods; margarine became the new norm on dinner tables and poaching skinless chicken was considered to be healthier than roasting it whole. Fat-free, highly processed, and sugar-laden foods came to be seen as healthy foods. As Barbara Moran wrote in Harvard Public Health magazine, “It was one big, happy, fat-free feeding frenzy—and a public health disaster.”2
After decades of following government dietary advice, the numbers on our health are staggering. In 1960, fewer than 13 percent of Americans were obese, and diabetes had been diagnosed in one percent of the population.3 Today, almost 40 percent of U.S. adults are obese4 (about 16 percent of children are)5 and nearly 10 percent of the population has type-2 diabetes.6 Conditions such as heart disease, stroke, and type-2 diabetes are the leading causes of preventable, premature death in our country.7
Since Keys’ original research, better-designed studies have proven that saturated fat is not, in fact, the dietary villain that public policy has made it out to be. For example, a study published in The Lancet late last year that included more than 136,000 people in 21 countries linked consumption of full-fat (i.e., saturated) dairy foods to a decreased risk of death from heart disease.8
In another review of 15 randomized controlled studies with more than 59,000 people, researchers found no statistically significant effects of reducing saturated fat on all-cause mortality or cardiovascular mortality and no clear effect on stroke.9
Other studies have shown that a low-fat diet that replaces saturated fat with polyunsaturated fats such as vegetable oils and carbohydrates increases the risk of coronary heart disease, cardiovascular events, and overall mortality.10 11
Fat is necessary for good health. It’s a clean-burning source of energy. It helps us absorb important fat soluble vitamins and phytonutrients such as lutein and lycopene. It’s an important component of cell membranes and the protective covering on our nerves. And it’s vital for a healthy brain.
Sugar and carbs, on the other hand…
The real culprit for our health woes is in our overconsumption of sugar and carbohydrates. The title of a 2018 study sums it up well, “Fat, Sugar, Whole Grains and Heart Disease: 50 Years of Confusion.”12
“The belief that a reduced intake of saturated fatty acids is the key dietary change for the prevention of coronary heart disease led millions of people to increase their intake of carbohydrates, most of which were refined,” wrote the study’s author. “Growing evidence points to refined carbohydrates, especially sugar-sweetened beverages, as being linked to risk of coronary heart disease.”
The reality for most Americans is that we are all consuming way too much sugar and carbohydrates. On average, we eat about 17 teaspoons (71 grams) of sugar per day. That adds up to an estimated 57 pounds of added sugar each year. As a comparison, Americans only eat an average of seven pounds of broccoli per year.14
And it’s not all coming from the typical culprits like cookies and candy. You can find added sugars in canned vegetables, cereals, peanut butter, yogurt, salad dressings, and more. Simple carbs like those found in pasta, pizza, bread, and tortillas (and which make up the bulk of most Americans’ carb intake) are rapidly converted to sugar in the body. And when it comes to drinks, the sugar also adds up quickly. A 12-ounce can of soda has about 11 teaspoons (46.2 grams) of added sugar. A 16-ounce Starbucks Vanilla Frappuccino® contains about 17 teaspoons (71 grams)15 of sugar.
“Sugar-sweetened beverage consumption is steadily rising among all age groups worldwide,” said M. Faadiel Essop, Ph.D., of Stellenbosch University in one study. “Our analysis revealed that most epidemiological studies strongly show that frequent intake of these beverages contributes to the onset of the metabolic syndrome, diabetes, and hypertension.”
Eating sugar, refined carbohydrates, and too many high-carb foods, including some whole grains, increases the amount of glucose flowing through your body, stimulating the pancreas to release insulin. These types of foods flood your body with glucose in excess of what it requires for immediate energy needs, and as a result, insulin signals the body to store all of the excess glucose as fat. Additionally, as insulin spikes, it increases levels of leptin, a hormone responsible for controlling appetite. If leptin levels stay too high for too long, it creates a condition where the body turns off its natural ability to gauge hunger and satiety (a condition called leptin resistance), which promotes weight gain.
Chronically elevated levels of glucose and insulin can lead to a myriad of health issues, including “cardiometabolic” conditions like metabolic syndrome (a cluster of symptoms including increased belly fat, fasting blood sugar, blood pressure, cholesterol, and triglycerides), type-2 diabetes, obesity, and heart disease.17
Additionally, excess glucose binds to proteins in the body, leading to the formation of advanced glycation end products (AGEs), which promote oxidation and inflammation in tissues like the endothelial lining of the arteries,18 and may also transform LDL cholesterol into a form that is prone to accumulate in the arteries.19 Population studies have shown that diets high in carbohydrates increase triglycerides and reduce HDL cholesterol.20
In addition to the negative cardiometabolic effects of sugar and a high-carb diet, cardiovascular research scientist James DiNicolantonio says that refined white sugar can be more addictive than recreational drugs (and studies back up the idea).21 22 23
“You get this intense release of dopamine upon acute ingestion of sugar,” he explains.24 “After you chronically consume it, those dopamine receptors start becoming down-regulated—there’s less of them, and they’re less responsive. That can lead to ADHD-like symptoms ... but it can also lead to a mild state of depression because we know that dopamine is that reward neurotransmitter.” Previous research has connected regular consumption of sugary foods and sugar sweetened beverages with a higher risk of depression.25 26 27
While the government and public policy stays entrenched in the “low-fat, high-carb” dogma, modern nutrition research continues to debunk the myth that saturated fat is bad for us, and a growing body of research is showing that sugar and excessive amounts of carbs are the true culprits in poor health. This is creating a shift that is encouraging more people to eschew sugar and excessive carbs and embrace healthy fats, including saturated fat. By 2021 all nutrition labels are required to include the amount of added sugars in a product, as per new rules from the U.S. Food and Drug Administration,28 making it easier to keep track of (and avoid) extra added sugar. And while you cut back on the sugar and carbs, make peace with fat, and know that it is an important part of a healthy diet.
Saturated Fat As Part of a Healthy Well-Balanced Diet
In my ten years of nutrition research and writing, the one piece of dietary advice that has been a constant is this: Eat whole, minimally processed, nutritious foods, as close to their natural forms as possible. This includes saturated fat. When we say that saturated fat can be a part of a healthy, well-balanced diet, this is not a call to regularly indulge in cheeseburgers, Italian subs, and cheesesteaks, while calling French fries and ketchup vegetables. A diet high in saturated fat combined with lots of carbohydrates and devoid of vegetables is not a healthy one. Consider my dinner last night—sirloin steak (a blend of saturated and unsaturated fats) cooked in butter (mostly saturated fat) and topped with a chimichurri sauce made from fresh herbs and olive oil (mostly unsaturated fat), served with cauliflower tossed in olive oil and roasted, and a salad topped with an olive-oil based vinaigrette. See how that works? Quality is important to consider as well; try to always choose organic vegetables, grass-fed meat, and pasture-based dairy, which will always contain a better quality of fat compared to factory farmed animal products. It’s time to stop villainizing fat in general, and saturated fat, in particular. Nothing in excess (except for maybe vegetables) is good for you. But neither is holding on to an outdated fear of fat.
– Lindsay Wilson