Body Composition 101: The Science Behind It – Part 1

20 Minute Fitness Podcast #003

Welcome to Part 1 of our Body Composition Series! Jump to Part 1 ・Part 2Part 3Part 4

This episode of 20-Minute Fitness marks the beginning of a 3-part series on body composition.

Understanding what our bodies are made off allows us to explore how to track any changes to our body as a result of exercise and balanced diet. Tracking progress is essential to make sure we are on the right path to achieving our goals.

Become a body-geek by following the series. Your journey starts here!

Show Notes

This episode of 20-Minute Fitness marks the beginning of a 4-part series on body composition. By this, we mean what our bodies are made up of, our biological make-up.

To introduce this subject, we split the body into 2 components, fat and fat-free mass. If we can better understand what our body comprises of, we can more easily comprehend the changes that will occur as we begin to workout and eat a more balanced diet.

You will be able to show off to friends and family with your new found knowledge on the subject of body composition by throwing around terms such as adipose tissue and subcutaneous fat.

In the following few episodes, we will look into how we can actually track changes to our body composition. We will look into the various advantages and disadvantages of each body composition analysis method.

We hope you enjoy being transported back into your Biology class and that you find this information valuable.



Hello and welcome back to the 20 Minute Fitness Podcast, this is episode number 3.

This podcast is powered by ShapeScale. ShapeScale is a 3D body scanning scale that is set to revolutionize the way we track our progress. Combining both visual queues of progression and real data, ShapeScale will keep you on the right path to achieving your goals.

We thought we would start a new series for our podcast and it is all about body composition. We want to understand what our bodies are made up of and how we can track any changes that happen to our bodies, as a result of our nutrition and exercise.

I hope you have found that in previous weeks that our delivery of the 20-minute fitness podcast is progressing and I really hope that you are enjoying the content. Please don’t forget to share it with your fitness-loving friends and family and also leave us a review!

Again, I am your host Charlie and I will be leading you on this mission to understand more about our bodies. Don’t forget, you can follow ShapeScale on our various social media channels for more updates and news. Our Twitter is @shape_scale, our Instagram is @shapescale and our Facebook is Shape Inc.

Let’s get into the show!

The First episode in our Body Composition Series will really cover the basics and it will hopefully give you an idea as to what the human body is made of.

According to the Mosby Medical dictionary, Body composition can be defined as “the relative proportions of protein, fat, water, and mineral components in the body. It varies among individuals as a result of differences in body density and degree of obesity.”

It is important to understand that there are different models of body composition. The most basic of these is called the 2 component or 2 compartment model, which obviously divides your body into two parts.

Before I explain this 2 compartment model it is also worth mentioning that the 2 component model assumes that the level of water in our bodies is constant. I will explain more about this later, why this is important.

But without further a due let’s start exploring the two different components.

These are your Fat mass and your Fat-free mass.

Fat mass refers to pure lipid molecules and fat-free mass is basically everything else. Your proteins, minerals, carbohydrates, water, everything other than lipid molecules.

When we talk about our fat mass, we are talking about adipose tissue, this is our fat tissue, it is not just pure lipid molecules but it also consists of the blood supply and connective tissue as well. I know I called Adipose tissue, Fat tissue but this is not just the fat you can see on your body.

It actually incorporates visceral fat and subcutaneous fat. Subcutaneous fat is the fat you see on your bodies. It is the layers underneath your skin. Whilst, visceral fat is around your intestines, pancreas and your heart.

Visceral fat is known to be the more harmful of the two and there have actually been quite strong links to obesity and cardiovascular disease. It is often higher in men.

But the fat we have or the adipose tissue we have, 60-89% of it subcutaneous fat, so the fat underneath our skin. That is why skin caliper fold tests can relatively accurately measure our body fat %, as they presume that all of our fat is subcutaneous.

This also illustrates one of the pitfalls of skin fold test. We are ignoring the fact that someone could have more visceral fat than someone else. For example, a skinny fat individual with a large beer belly may have a lot of visceral fat but they have relatively little, jiggly, subcutaneous fat. This is why there are inaccuracies related to skin fold tests.

It is actually advised, instead of using the calculations and equations that derive from the skin fold measurements you should look to see if your skin folds are decreasing in millimeters.

We have fat all over our bodies, even our brain is 60% fat.

But we can work to lose this fat and you all know that is by working out and eating right and leading a healthy lifestyle. However, only a few machines such as an MRI will actually be able to distinguish between what type of adipose tissue you are losing. Are you losing visceral or subcutaneous? You won’t really know unless you go for an MRI scan.

Before we move onto fat-free mass and what that consists of, we will look at why we do need fat.

Fat allows the body to store energy, it acts as an insulator and it regulates our body temperature. It also cushions our internal organs. So we can already see that fat is still essential to our body and our wellbeing.

For women, it is advised not to decrease your body fat percentage to any lower than 10 to 13 percent. And according to the American Council on Exercise, men should go no lower than 2 to 5 percent, but that is very low, that is fat that is essential to your survival.

Athletic women, on the other hand, are in the range of 14 to 20 percent and athletic men are anywhere between 6 and 13 percent. So finding the right balance is really key!

Right onto fat free mass and the thing we are focusing on obviously is muscle mass or skeletal muscle. This is what changes as we begin to train and workout hard and things like that. It is all the muscle in the body excluding smooth muscle and cardiac muscle, which is found around the heart and the organs.

Our skeletal muscle can change according to the way we train, our age and diet. So for example, if we are in a calorific surplus and progressively overloading our muscles, we would hope to be increasing our skeletal muscle mass. Whilst, if we are looking to lose body fat and we are eating in a deficit or taking in less energy than we are expending, we are often sacrificing skeletal muscle mass to lose body fat.

Skeletal muscle contains anywhere from 60-80% water, about 20-33% protein and 2-3% intermuscular fat. 75% of skeletal muscle is found in the arms and legs.

So obviously I said earlier that body composition tests in the 2-compartment model, maintain that the human body has constant total body water. However, it has just become evident that our muscle has 60-80% water within them. Really then, this is not a constant. We can manipulate our body composition by hydrating and dehydrating our bodies, which changes the level of water within our muscle and adipose tissue.

Even taking a supplement like creatine can actually make the water levels within your tissues fluctuate.

Creatine is an amino acid, that we usually get from seafood or red meat but we can take it as a supplement. Our body converts creatine to phosphocreatine and stores it in our muscles, it is then used for energy. As a result, people take creatine to improve athletic performance, build muscle mass, build strength and all that.

It has actually been proven that creatine increases total body water because water enters muscle cells as well as the creatine when we start to supplement it.

So we can already see that total body water does not stay constant in our bodies which is something that the 2-compartment body composition tests, neglect.

As well as the fact that the water levels vary throughout the day, the level of water we retain is always changing. In fact, we lose 9% of total body water over a day which on average equates to about 6.88pounds of water. So about 3 and a bit kilograms of water we are turning over throughout the day.

We can, therefore, see that it definitely would have an effect on our body composition tests.

So the 2 component model does have its flaws. Another one being that it does ignores the bones completely.

A DEXA scan, which again we will look into next week, uses a 3-compartment model. So it considers bones in its body composition analysis.

On average our bones make up 4% of our bodies so they do have a part to play in our body composition. Our bone density increases until we are about the age of 30. So this does change!

Before we sign off and finish this podcast, I would like to give some recommendations and benefits of maintaining a healthy body composition.

The first one is obviously, by working to lose fat, by working to maintain a healthy body composition and visceral is the more concerning of the two, we can decrease our risk of developing diabetes, metabolic diseases and osteoporosis and a whole host of other diseases.

Regular physical activity has been associated with so many benefits, such as increased energy, a more stable state of mind, it is good for your mental health, it releases endorphins, it can help you de-stress after a long day, it can help you maintain your cognitive function. A whole host of benefits of keeping active and fit and looking after your body.

The American College of Sports Medicine (ACSM) and the American Heart Association (AHA) suggest doing at least some moderate intensity cardio for 30 minutes a day, five days a week or high-intensity intense training 20 minutes a day, for three days a week is a great start. Also incorporating strength training movements into that. So 8 to 10 strength-training exercises, such as your pushups, pullups, planks and working to do those at least two days out of the week we have.

Well, that is all we have time for this week. I really hope you have gained a greater understanding of what our bodies are made up of, why we can’t really rely on body composition tests to tell us our bodies are made of. I hope you are looking forward to finding out more about the different types of tests like hydrostatic weighing, using tape measures to calculate body fat percentage, more about ShapeScale. We will talk about DXA scans and bioimpedance, so there is lots to discuss next week as well.

So I hope you gained some value from this and learned something about adipose tissue or skeletal muscle mass and if you did we would really appreciate a review on Itunes or Google Play or Stitcher. Or even recommend us to your friends or share the podcast because we are just starting to get into podcasting, it is new for us and we would appreciate any feedback and any help we can get on the subject.

So if you have any advice for us, or if you have anything you would like us to cover as part of the body composition series then please don’t hesitate to get in touch. My email is charlie@shapescale.com
I would appreciate any feedback.

We will see you next week and I hope you enjoyed the show.

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You have listened to Part 1 of our Body Composition Series! Jump to Part 2Part 3Part 4

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Charlie Farmer

Charlie is content writer and community manager at Shape.
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