There is a lot of bad press surrounding dietary fat. However, the truth of the matter is that fat is an essential part of our diet and not all fats are bad.
Briefly, fats, also known as lipids, come in many forms. The most notable forms pertaining to this article are; triacylglycerols (formerly known as triglycerides), sterols (cholesterols), and lipoproteins.
Triacylglycerols represent most of the stored energy within our body fat. Moreover, triacylglycerols make up approximately 95% of our dietary fat. Lipoproteins constitute a mix of lipids and proteins that transport lipids via our blood. The main lipoproteins that allow this are the two cholesterols, low-density lipoprotein (LDL) and high-density lipoprotein (HDL).
Three reasons fat is essential
Body fat stores energy, nutrients, and toxins, provides protection to our internal organs, and helps regulate our body temperature by insulating against heat loss.
The cholesterol we consume in our diets helps form the plasma membranes of our cells. It also acts as a precursor for many important steroids in the body, including the bile acids; steroid sex hormones such as estrogens, androgens, and progesterone; the adrenocortical hormones; and vitamin D.
Cholesterol is important for cognitive function as your brain makes up only two percent of your body weight but contains 25% of your body’s cholesterol. Moreover, that 25% of cholesterol helps form our myelin sheath which coat the outer parts of the neurons in our brains. Neurons are special structures that mimic highway roads carrying signals within us.
In other words, neurons are the roads that make up the highways and myelin sheath are the guardrails on either side of the road. Thus, in our brain, for us to be able to recall how to do everyday tasks, recall memories, and communicate externally and internally, our myelin sheath need to be fully intact or those signals will get disrupted or blocked.
As you might have guessed, this is a primary factor in people with Multiple Sclerosis and Alzheimer’s disease. As a result, a diet deficient in fat is linked to a decline in cognitive function and memory. In addition to being a potential risk factor for developing Alzheimer’s.
Now wait, I thought cholesterol is bad for you?
It is important to understand that cholesterol is not inherently good or bad. In general, doctors consider it as a good thing to have low levels of circulating LDL and high levels of HDL. Therefore, LDL is considered the “bad” cholesterol and HDL is considered the “good” cholesterol. Indeed, it is good for your overall health to have lower LDL than HDL. Thus, it is more about the ratio of LDL:HDL. Although the ratio between HDL and triacylglycerols is becoming a better indicator of disease but, that is for another discussion.
Functions of LDL and HDL
Both LDL and HDL have important functions within the body. In short, the liver also stores triacylglycerols but in a limited capacity. Consequently, LDL is called upon to transport the triacylglycerols throughout the body to be stored and utilized for energy. To help explain HDLs function we will go back to our highway analogy.
On this highway, HDL are like recycling trucks. The HDL go out and scavenge any unused fat and bring it back to the liver to be converted into bile and eventually excreted. The LDL are more like moving trucks transporting the triacylglycerols from the liver to our cells throughout the body.
The LDL are smaller and therefore, cannot carry as many triacylglycerols. So, these moving trucks tend to overflow and leave stuff behind on the road. This usually happens when there is a high amount of triacylglycerols the liver cannot store and is therefore circulating in the blood.
These left behind particles is what contributes to plaque build up in our arteries and potentially leads to cardiovascular disease. That is to say, if our HDL recycling trucks are not able to pick them up and shuttle them back to the liver. There are many reasons as to why this process falls apart, one of them being not eating enough healthy fats!
The final word
Alright, time to reign it back in. Long story short, the fat we eat supports many essential functions within our body. Simply put, if we do not eat enough healthy fats our body’s will suffer the consequences. As a result, unnecessary health issues may arise. Healthy fats will support a better LDL:HDL ratio and a better HDL:Triacylglycerol ratio. This in turn supports overall health and thus, dietary fat is an essential part of our diets.
Stay tuned for more articles on this topic such as the difference between saturated and unsaturated fats and more!
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Author: Jon Esposito MA, CSCS, CISSN, USAW