I vividly remember my first undergrad nutrition class. I went into my college career thinking I had a good grasp on nutrition. I knew that fruits, vegetables, and grains were good for you and meat was bad for you. And yes, I was a vegetarian in case you were wondering.
In my head, it was simple. Meat was bad because it contained cholesterol. Dietary cholesterol raises your blood cholesterol, and that causes heart disease. That just made sense.
It wasn’t until my first undergrad nutrition class that this idea was challenged. I was a few weeks into the course and I felt comfortable enough, until my teacher threw this one at me:
“Saturated fat raises your blood cholesterol more than dietary cholesterol does.”
And on top of this, apparently the dietary cholesterol limit was eliminated from the dietary recommendations! I was understandably confused, as were many of my classmates, but what I learned that day was something that has stuck with me ever since: nutrition is complicated.
What are saturated fats?
Before I get too off topic, let’s get back to saturated fat specifically. Let’s start with some important background info. If you are already well versed in nutrition, you may be familiar with this.
There are four main categories of fats. Polyunsaturated, monounsaturated, saturated and trans fats. (source) Unsaturated fats are fat molecules that form more than one double bond between carbon molecules. (source)
There are two types of unsaturated fats: polyunsaturated and monounsaturated. Within polyunsaturated, there are two main categories, omega-3 and omega-6 fatty acids. (source)
Saturated fats are fat molecules with no double bonds between carbon molecules. (source) That probably isn’t super meaningful to you unless you are a chemistry wiz, but basically what this means is that saturated fats are solid at room temperature.
Some examples of foods higher in saturated fat include butter, coconut oil, milk, cream, cheese, palm oil, sausage, hot dogs, bacon, chicken with skin, and fattier cuts of meat such as pork and steak. (source) (source)
The foods higher in saturated fat, such as butter, are completely solid at room temperature, while foods lower in saturated fat are more liquid at room temperature. Ever notice that white fatty strip attached to your steak? That’s high in saturated fat.
Trans fats are found in small amounts naturally in some animal products, but became notorious when companies began a process called hydrogenation to make vegetable oils solid, such as in margarine. Little did they know trans fat consumption increases your risk of heart disease more than saturated fat. (source)
Current recommendations and research
The American Heart Association and American Cancer Society recommend no more than 5-6% of your daily calories to come from saturated fat. The Academy of Nutrition and Dietetics recommends no more than 10%. (source) (source) (source)
So where did these recommendations come from? And should we listen to them?
Well, they come from research. Experts in the field have the responsibility to look at the current research on the topic and create recommendations that are easily digestible for the general public.
But, when examining research we can’t just look at one study and be like okay, excess corn consumption is the new cause of ovarian cancer. We need to look at the general consensus of multiple studies. An example of this is a systematic review.
Does saturated fat cause heart disease?
A recent systematic review, published in 2017, does just this. It looks at research from 2010-2017 to came to a conclusion about saturated fat and its effect on heart disease.
The general consensus revealed that reduction of saturated fat alone is not enough to reduce risk of heart disease. Replacing saturated fat with carbohydrates does not lower heart disease events or death from heart disease. But, replacing saturated fat with polyunsaturated fat, monounsaturated fat or high quality carbohydrates does lower heart disease events. (source)
To put this into food terms, replacing a daily 8 oz. steak with 8 pieces of white bread is not going to lower risk of heart disease. But, if it were to be replaced with a whole wheat pasta dish with lots of olive oil, olives, garlic, veggies and chicken breast, then risk will be reduced.
But, these results were only looking at saturated fat with its relation with heart disease. Though this is the number one killer of Americans, we do need to consider other conditions. (source)
Does saturated fat cause diabetes?
So, what about diabetes?
In a systemic review conducted in 2008, multiple randomized control trials studying the effect of different dietary fatty acids (unsaturated, saturated, trans fats) on insulin sensitivity and type 2 diabetes in humans were examined.
All the studies they looked at were controlled for dietary compliance, or how well the subjects stuck to the diet, and body weight stability, if the subjects maintained the same weight throughout the study. This is especially important because independent of what the subjects are eating, losing weight typically improves health markers. (source)
Three of these studies showed high saturated fat diets lead to decreased insulin sensitivity (worsened diabetes) versus high unsaturated fat diets.
Twelve of these studies found no effect relating any type of fat with insulin sensitivity, but these studies have multiple flaws according to the authors.
The highest quality study reported the most significant decrease in insulin sensitivity in a high saturated fat diet compared to a high monounsaturated fat diet. (source)
The basic conclusions of this study were that there simply needs to be more research. Yes, three of these studies showed a correlation between high saturated fat intake and worsened diabetes, but twelve of them showed no correlation. More high-quality studies need to be done.
Future directions
So, what can I say to sum this whole post up? The current research on high saturated fat diets suggest that replacing saturated fats with unsaturated fat and high quality carbohydrates will reduce risk of heart disease, and high saturated fat diets may decrease insulin sensitivity compared to high unsaturated fat diets.
Now, saying this, research is always adapting and changing. More studies will come out that are higher quality, study more specific nutrients, and have larger sample sizes. Either we will gain more confidence in our current recommendations, or we will begin to question them, such as in the case of cholesterol. This is simply the nature of science!
In the future I would love to see more studies done on saturated fat. For example, I would love to see if replacing saturated fat with omega-3 fatty acids is different than replacing it with omega-6 fatty acids.
I would love to see if high saturated fat dairy is more beneficial than high saturated fat meat. I would love to see more studies controlling for weight maintenance, nutrient intake, calorie intake, and exercise. This would be the next step in making more accurate claims regarding saturated fat.
Hopefully, I will be able to revisit this topic later on as more studies come out, but as for now, these are my thoughts.
In conclusion, should I eat saturated fat?
When it comes to my overall diet, I keep it simple. I just eat a balanced diet. Every day I eat vegetables, fruit, whole grains, lean meats, nuts, seeds, dairy, and oils. I don’t cut out food groups, even the “bad” ones.
I eat red meat about once or twice a week, I cook with olive or avocado oil, I throw in some vegetarian meals, I eat full-fat dairy sometimes and low-fat dairy other times. I even eat cookies made with butter and refined grains and sugar.
Not one nutrient or food is going to kill you if you are eating everything in moderation. I think people tend to overanalyze certain nutrients and think that if they have even a little bit of it they will get some crazy autoimmune disease (I’m talking about you, lectins – I have an article on this one as well).
So, should you be scared of saturated fat? The answer is no. Having a steak when you go out for dinner isn’t going to hurt you. A tsp of butter on your toast isn’t going to hurt you. As long as you treat every food with moderation, you will be fine, trust me.
Now, if you feel like you are going a little overboard – for example, you have steak two times a day and strictly cook with butter – then it’s ok to want to make a change, but it doesn’t have to be extreme. Maybe switch to olive oil for one meal, or try a leaner steak. You don’t have to go all in overnight.
Here is the takeaway message: if you don’t already eat a ton of high saturated fat foods, you don’t need to worry about making a change. If you do eat a good amount, it would likely be beneficial to try making a few little swaps. It’s really that easy folks, thank you for reading!
Comment if you have any questions or have any other topics you are dying for me to write about! I really appreciate the feedback.
