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The Harmful Effects of Saturated Fat (In Excess)

Written by Joe Cohen, BS | Last updated:

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Note that each number in parentheses [1, 2, 3, etc.] is a clickable link to peer-reviewed scientific studies. A plus sign next to the number “[1+, 2+, etc...]” means that the information is found within the full scientific study rather than the abstract.

Saturated fat, in excess, can increase the risk of a variety of health problems. Read this post for a summary of scientific research into this topic and to hear my own personal thoughts on the topic.

First, I would like to start out by saying you should follow whatever diet you feel best from. I think people are built differently and benefit from different approaches. Many do great on consuming lots of saturated fat, while others don’t. Personally, it’s very bad for me.

Second, see my article on getting into ketosis.

Saturated Fat Leads To Inflammation and Insulin Resistance

Saturated fats like Palmitic acid [1], Myristic acid [2], Lauric acid [3] and Stearic acid [4] all cause insulin resistance. These are found in oils that some people view as beneficial such as coconut oil.

Different fatty acids affect insulin and glucose in different ways [5].

Palmitic acid has the most negative research behind it, but the others aren’t spared.

Excess Lauric acid, the main fat in coconut oil, increases inflammation [6].

A high-fat diet rich in saturated fatty acids (SFA) increased the number and inflammatory activity of macrophages in fat cells [6].

Saturated fat increased inflammatory gene expression by TLR4 and NFκB.

“Taken together, these data show that SFA is particularly potent in recruiting and activating immune cells in fat tissue, thereby increasing inflammation” [6].

Saturated fat, especially palmitate, increased TNF levels and lowered adiponectin, whereas unsaturated fat had no effect [6].

Palmitate can also induce insulin resistance decreasing mitochondrial function and insulin-stimulated glucose uptake via decreasing PGC-1a, the master mitochondrial regulator [6].

By decreasing mitochondrial function in muscle tissue, SFA consumption would lead to decreased oxidation of fat and glucose, thereby increasing their accumulation in tissues and blood [6].

In a study that tried to mimic the effects of low carb diets in rats concluded the following:

“Taken together, these data show that a lack of dietary carbohydrates leads to glucose intolerance and insulin resistance in rats despite causing a reduction in fasting glucose and insulin concentrations. Our results argue against the beneficial effects of LC-HFDs on glucose and insulin metabolism, at least under physiological conditions. Therefore, use of LC-HFDs for weight loss or other therapeutic purposes should be balanced against potentially harmful metabolic side effects” [7].

The Harms of Saturated Fats (In Excess)

I don’t believe consuming saturated fat in moderate amounts will hurt, but consuming excess amounts can potentially raise your risk for disease.

According to the World Health Organization, the evidence is “convincing” that consumption of palmitic acid increases the risk of developing cardiovascular diseases, placing it in the same evidence category as trans fat [8]. The WHO has some of the best and brightest scientists working for them and they aren’t influenced by industry.

A misconception that some people have is that most of the studies use hydrogenated saturated fat and in some way, the fats from the oils they consume are magically different. This is a fallacy.

One can argue that the research even downplays the harms of saturated fat because most of the epidemiological studies done looking at the changes in saturated fat intake don’t also account for the negative health effects of an increase in refined carbohydrates when saturated fat is reduced. Refined carbs in excess can be worse than saturated fat in excess.

Excess saturated fat:

  • Increases heart disease risk. A 2012 systematic review from The Cochrane Library analyzed 48 studies conducted between 1965 and 2009 and included 65,508 participants. All studies reduced or modified participants’ dietary fat or cholesterol for at least six months by at least 30 percent. It was found that reducing saturated fat by reducing and/or modifying dietary fat reduced the risk of having a cardiovascular event, such as heart attack, stroke, and unplanned heart surgery, by 14 percent [9]. There’re conflicting studies on this but a Cochrane review is always the most reliable.
  • Causes inflammation and insulin resistance [10] (Experienced this)
  • Deteriorates physical performance and cognitive function in animals [11] (Experienced this)
  • Causes hypothalamic inflammation [12]
  • Is associated with lower sperm quality. There was an association with reduced semen quality among 701 young Danish men from the general population. A significant dose-response association was found, and men in the highest quartile of saturated fat intake had a 38% (95% CI: 0.1%, 61%) lower sperm concentration and a 41% (95% CI: 4%, 64%) lower total sperm count than did men in the lowest quartile. No association between semen quality and intake of other types of fat was found [13].
  • Reduces brain-derived neurotrophic factor (BDNF) and therefore aggravates the outcome of traumatic brain injury on hippocampal plasticity and cognitive function by [14].
  • Causes a leaky brain by damaging the brain barrier [15] (Experienced this)
  • Impairs memory by impairing hippocampal energy metabolism [16] (Experienced this)
  • Causes inflammatory bowel diseases (IBD) in people with a genetic predisposition [17].
  • Induces weight gain [18] (Experienced this)
  • Causes gut permeability [18] (Experienced this)
  • High saturated fat and low starch and fiber are associated with hyperinsulinemia in a non-diabetic population [19] (Experienced this)
  • Increases risk of breast cancer [20]
  • Increases risk of ovarian cancer [21]
  • Increases risk of prostate cancer – myristic acid [22] and palmitic acid [23]. Dairy products may be associated with an increased risk of prostate cancer as well [24]
  • Decreases bone density in humans.
  • Worsens mood. Substituting dietary monounsaturated fat for saturated fat is associated with increased daily physical activity and resting energy expenditure and with changes in mood [25] (Experienced this).
  • Blunts HPA function in pigs [26]
  • Worsens the gut microbiota composition and increases its intestinal permeability through the induction of TLR4 [27] (Experienced this)
  • Increases LDL cholesterol … Substituting polyunsaturated fat for saturated fat reduces LDL cholesterol and the total cholesterol to high-density lipoprotein cholesterol ratio [28].
  • Increases aortic calcification by causing oxidative stress, leading to arterial stiffness [29]
  • Causes a fatty liver [30]
  • High-fat consumption causes atherosclerosis, independent of the fatty acid type consumed or of being lean or obese [31].
  • Induces inflammation, atherosclerosis, and ectopic fat deposition, whereas an equally high dietary unsaturated fat load, does not induce these abnormalities and shows beneficial effects in diabetic pigs [32].
  • May lead to depression, cognitive dysfunction, dementia, and neurodegenerative diseases by altering the Histamine 1 Receptor binding densities in various brain regions… many of these changes can be prevented by adding DHA, GOS or RS to the diet [33].

What’s My Position on Saturated Fats?

First, it’s important to keep in mind that most of these studies are dealing with excess consumption of saturated fat.

I don’t advocate a low-fat diet since it’s not either optimal. I find no harm to myself when I eat under 30g of saturated fat a day (recommendations by mainstream health organizations is to get under 15g a day).

The fat I get from foods is from whole food sources or from healthy oils like extra virgin olive oil and Black Cumin Seed Oil (these also have palmitic acid in them). The only fat that I consume that is mostly saturated is Ghee, and I try to not consume more than a tablespoon a day.

But again, there’s scientific evidence and your own personal experiments. As always, listen to your own body and ignore all other evidence. If you feel better consuming copious amounts of coconut oil then do it and ignore this post.

Coconut oil can be very beneficial for some conditions like candida. I also think Caprylic acid and Capric acid are very healthy, both of which are found in coconut oil.

Saturated Fats Concluding Remarks

While reading this article, it may seem like I believe saturated fats are “bad.” I think the story is more complex than that. It all depends on what you replace it with, genetics, and other factors like a number of calories you consume. When you consume fewer calories than you need, saturated fats won’t cause much insulin resistance.

Also, if you’re overweight, your muscle insulin receptors are probably already insensitive, so eating saturated fat probably won’t make much of a difference and could maybe even transiently be beneficial if it curbs appetite and helps you lose weight.

I did notice on the diet that it curbed my appetite so I can see the appeal in that regard (a starch-based diet also curbs hunger and limits caloric intake).

Experiment for yourself and don’t listen to gurus. See what works for you.

I welcome dissenting opinions and studies that counter the points I make. Please post studies and not links to bloggers.

How Cholesterol Causes Heart Disease

Saturated fat increases LDL cholesterol, which is implicated in heart disease.

We have tried nearly every diet you can find and have discovered that the healthiest diet for people with food sensitivities is the lectin avoidance diet. Try our cookbook to get started! We promise the food is delicious!

About the Author

Joe Cohen, BS

Joe Cohen, BS

As a kid, Joe suffered from inflammation, brain fog, fatigue, digestive problems, mood and other issues that were poorly understood in both conventional and alternative medicine. Frustrated by the lack of good information and tools, Joe decided to embark on a journey of self-experimentation and self-learning to improve his health--something that has since become known as “biohacking”. With thousands of experiments and pubmed articles under his belt, Joe founded SelfHacked, the resource that was missing when he needed it. SelfHacked now gets millions of monthly readers. Joe is a thriving entrepreneur, author and speaker. He is the CEO and founder of SelfDecode. His mission is to help people gain access to the most up-to-date, unbiased, and science-based ways to optimize their health.


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