Coach Mary's Tasty Tips #5

Thursday, February 22, 2018 - 13:27
Hi gang,

Welcome back. Today is the last introductory post about macronutrients; we have talked about carbs and proteins in the past couple weeks so today I will be talking about fats. This macronutrient tends to be either loved or hated by people, depending on how much they like bacon and cheese; I personally think it is an important one but I don’t really crave or care for it too much.

Most of the fats that are present in the food we eat are either in the form of triglycerides or cholesterol. Triglycerides are the most abundant and they are complex molecules composed of one glycerol molecule connected to three fatty acids. Cholesterol is a very distinct molecule with different roles from those of triglycerides and is composed of 4 rings connected to form a bulky structure. This is a very basic idea of what these two main fats look like at molecular level, but now let’s see how they look like in our day to day lives and what they do once digested and absorbed by our gut.

So, as I mentioned, 3 fatty acids and 1 glycerol make up one triglyceride molecule. The fatty acids are made up of carbon and hydrogen atoms bonded in a semi-linear form to form a sort of a “tail”. The structure of these tails attached to the glycerol is what determines whether a fat is considered saturated or unsaturated, depending on the number of hydrogens connected to each carbon atom. Saturated fatty acids have all carbons connected to at least two hydrogens (i.e. they are all connected by single bonds), making their structure very stable and solid at room temperature. They can be found mostly in animal food sources such as meat, butter, and cheese. Unsaturated fatty acids, on the other hand, have one of more carbons connected to only one hydrogen atom (i.e. they have at least one double bond), making their structure “kinked” and liquid at room temperature. These are mostly from vegetable food sources and can be divided into mono and polyunsaturated fatty acids. Monounsaturated fats are present in olive oil, peanut oil, canola oil, most nuts, and avocados, while polyunsaturated fats are present in corn oil, sunflower oil, fatty fishes, and walnuts. Omega-3 and omega-6 are two specific types of polyunsaturated fats and they are considered essential, which means our bodies cannot make them from scratch, just like the essential amino acids I mentioned last week. These are very important but complex to understand, so I will dive more into that topic on a later post. We have all heard that saturated fats are “bad” and unsaturated fats are “good” but, although this is for the most part correct, things are a bit more complex than that. The association between saturated fats and cardiovascular disease isn’t very clear, but it is well known that replacing dietary saturated fats with unsaturated ones has a beneficial impact in your health and can reduce the risk of developing certain diseases. So go ahead and ditch that butter and replace it by some tasty olive oil. ;)

Cholesterol is another really important fat and it is present in many animal-based foods such as eggs and red meats.  Cholesterol tends to have a bad reputation due to its association with cardiovascular disease but, in reality, even though high blood cholesterol is associated with certain diseases such as cardiovascular diseases, it has been proven that it does not have a direct relation with dietary cholesterol. This relationship is much more complex; there are several factors unrelated to dietary cholesterol intake that have an impact in blood cholesterol levels so, for most people, there is no need to cut out cholesterol from their diet.

Once fats are digested and absorbed in our guts, they are used for a variety of roles. Triglycerides are used mostly for energy, while cholesterol is used to make the membranes of our cells, transport molecules throughout the body, and make important hormones such as estrogen, testosterone, and vitamin D (not exactly a hormone but also important). When not used for any of these roles though, fat is stored as triglycerides in adipose tissue. Adipose tissue is not only the “belly fat” and the “muffin tops” that we all know too well, but it is also the fat that covers most of our organs, keeping them protected and insulated from their surroundings. So, even though too much dietary fat can be unhealthy for you, it does not necessarily mean that the less you eat and the less you have in your body, the better it is for you; there is a limit to healthy “leanness”, which is called essential fat. Essential fat is the one that is located within some of your organs, bones, and muscles, keeping them “protected” and working properly. Women have a higher percentage of essential fat in their bodies than men due to the sex-characteristic fat related to child bearing. Essential fat in women ranges from 10-13% and from 2-5% in men; it’s quite different! The remainder of the adipose tissue in our bodies is called non-essential or storage fat, and this can be located superficially, under the skin, or more internally, around your internal organs; this is the fat that can increase and decrease a lot according to one’s lifestyle choices and that, in large amounts, can put people at an increased risk for certain diseases.

The last kind of fat important to mention is trans fat. This is a chemically modified fat that has been associated with several kinds of cancers and cardiovascular diseases. I am not even sure if this fat can still be found in any product in Ireland, but in case you ever come across it at some point, make sure to avoid it.

Before I end this post I just want to mention that 1 gram of fat has 9 kcals (which is different from proteins and carbs that only have 4kcals per gram). This is what makes fat our highest source of energy and makes fat storage so appealing to our body, ironically (it still thinks we live in the ice age and we have a hard time getting food). Food is stored as fat when eaten in excess and, unlike what people may think, you don’t have to eat too much fat to gain body fat; excess carbohydrates and protein can also be stored as adipose tissue as soon as your body’s storages for that specific macro are full.

Now go and try not to think about all this next time you eat a cheeseburger. You’re welcome! J