For anyone who hasn’t been keeping up with all the posts here at Burn the Fat Blog, the team at Examine.com wrote our “most liked’ post ever a few months ago, in which they talked about the actual science behind 10 popular fat burners. They did a great job taking complex science and making it accessible to you, and so for an encore, I asked them to give us the straight skinny on saturated fats. Here’s what they have to say:
Dietary fats (aka fats) are a large group of similar-molecules, and are one of the three major macronutrients (carbs and proteins being the other two). Just like proteins are made up of amino acids, fats are made up of fatty acids. Fatty acids are characterized with long chains of carbon molecules string together; when three of them come together, you get a triglyceride (you may have heard of that word before).
We’re about to make sense of a lot of fat terms you may have heard of, so read through this carefully.
Just like carbs and proteins can differ, so too can fats and their fatty acids. You have the much loved fish oil fatty acids – EPA and DHA. You have the overrated fat-burning fatty acid – CLA. You have olive oil and its magical Mediterranean oleic acid. You even have fatty acids that can literally give you heart lesions (erucic acid, which was genetically out of rapeseed oil). There is of course the universally reviled trans fat. Heck, even some of the up and coming supplements have fatty acids as their primary ingredient (such as royal jelly).
Because there are so many variations, we need a way of classifying them.
There are three primary parameters:
How long the carbon chain is (short, medium, or long). You may have heard of coconut oil and its healthy MCT fat, aka medium chain triglycerides
If the carbon chain has double bonds. Saturated fats have no double bounds, whereas unsaturated fats either have one (monounsaturated) or multiple (polyunsaturated, aka PUFAs).
For unsaturated fats only, how the bonds are positioned. This is where we get trans fats from.
So even when we talk about just saturated fats, the length of the carbon chain can vary. There are 10 saturated fatty acids common in our diet, and thus it’s not easy to just “talk” about saturated fats – we are talking about different molecules that can have different effects!
It’s also hard to test out the effects. For example, if you replace carbs with fats and note a change, was it due to the introduction of fats, or due to the exclusion of carbs?
Studies on saturated fat intake and cardiovascular health tend to follow groups of people over time and survey what they eat. When people in that group are found to have some cardiovascular issue, we try to analyze the data to figure out what could have caused the issue. This is called an epidemiological survey.
There are many meta-analyses on these surveys already conducted, and they generally state:
Just looking at people who eat saturated fats vs those who don’t, you have a higher risk of cardiovascular disease (CVD) if you do eat saturated fats. This is without analyzing any other details.
When we analyze the rest of people’s diets, saturated fats do not associate with CVD1,2.
Saturated fats do increase LDL cholesterol, but that increase does not correlate with an increase in CVD3.
When you tell people to avoid saturated fats, they also tend to reduce refined carb intake. This reduction of processed carbs could be the reason why CVD risk decreases4.
To simplify, we know that constantly eating fast food will likely give you heart disease. As the burger is the main component, it gets blamed, and from that, the fatty acids are blamed. The actual culprit is either the buns and fries (with the burger), or some kind of negative interaction between the burger’s fatty acids and the bun/fries’ processed carbs.
We know that fat is more satiating (makes you feel more full) than carbohydrates5. When saturated fats are actually compared with PUFAs (plant based) or other monounsaturated fats, the satiety is equivalent6,7,8. While these studies did not measure weight over time, there were controlled interventions and suggest no significant effect of saturated fats here.
Fats tend to suppress appetite, but saturated fats have no additional suppressing-benefits than other fatty acids.
Now, a particular subset of ‘saturated fatty acids’ includes the medium chain triglycerides (aka MCTs). This term refers to the saturated fatty acids between 8 and 10 carbons in length and tends to refer to lauric acid, myristic acid, and caprylic/capric acid. In short, these are the fats that have made coconut oil very popular.
When looking at studies on coconut oil or MCTs in particular, there does appear to be slight weight loss effect when compared to other fatty acids. It should be noted that this happened when you replaced existing fat consumption with MCT fats, not just adding more calories to the diet. Still, it should be explicitly noted that the weight loss benefits were minimal. In fact, a good article and summary on this topic to read on this topic would be Bryan Chung’s “The lime in the coconut is purely optional” where he conducted a personal and small meta-analysis on studies and did find a weight loss effect, but it was pretty small.
There may be positive effects on weight loss associated with coconut oil/MCT fats, but the overall effect is pretty small and would likely only benefit weight loss if these fatty acids replace other fatty acids while calories are kept constant. The effect is too small to overcome the caloric content of the fatty acids themselves
A major claim for saturated fats for athletes and people looking to lose weight is that they can stimulate the production of androgens and other steroid hormones, which then promote beneficial changes in body composition.
Similar to appetite suppression, having an intake of dietary fat appears to be better for steroid hormone production than a low intake of fatty acids. Cohorts with lower fat intake have less androgen levels9. Testosterone can be either reduced by putting men on a low fat diet10 or increased with a high fat diet11. Still, the magnitude of change is roughly 12-13%, which may sound impressive, but is quite a small amount. To compare, testosterone injections usually give you 100%+ more testosterone12 although some studies have noted up to 400% at peak levels with testosterone itself13 We should note that this is for medically supervised therapy; steroid cycles are likely much higher.
Despite the above evidence, there is actually no well controlled interventions assessing the saturated fatty acids versus other fatty acids. When we look at survey research there doesn’t appear to be any promising correlations14. If there is a promising correlation, it seems to be with monounsaturated fatty acids15.
Fatty acids themselves increase testosterone when in surplus in the diet (when compared to a low fat diet), but the change in testosterone is actually pretty small. When looking at saturated fats in particular, there is no evidence to suggest that they are somehow better than other fatty acids.
Overall, we can confidently stated that saturated fats are not much better or worse than other kinds of fats. The worry that saturated fats will cause cardiovascular harm is most unfounded, but they don’t appear to give significant benefits either. Their role in testosterone production is overrated, and if there are any fatty acids you should keep an eye on, they would be the omega-3 and omega-6 fatty acids.