What is bodyweight really, and what is it composed of?

Hands up who wants to lose weight.


That’s probably a few of you, but have you ever sat back to think about what that really involves?

Are you losing weight because you have a set number that you perceive to be ideal?

Have you given consideration to what kind of weight you are losing?

What time frame are you working with?

Have you got a defined starting point?

Do you know what your current calorie intake is, or what it needs to be?


These are just a few questions that need to be addressed before you can start your journey and in this article, I plan to guide you through the minefield that is dieting.


First of all, you need to realise that your weight is just your relationship with gravity and is a combination of a lot of individual components.

                When you step on the scale, it gives you a number, that’s it, nothing more! This information isn’t particularly useful as it doesn’t tell you what that weight is made of.

At any given time, your weight is composed of the following, and can change quite drastically.

·         Skeleton, a human skeleton weighs between 2 and 4 kg and fluctuates depending on the health of the bones. When you begin weight training, you force the skeleton to adapt by increasing in density to cope with the loads and stresses you are now asking it to bare, conversely, inactivity and bone disease such as osteoporosis can result in a reduction of bone density, therefore weight and also structural integrity.

·         Essential organs, your heart, brain, liver, kidneys, lungs intestines, arteries and veins. Basically, anything that keeps you alive. There is very little change in the weight of these, so mostly we can rely on this as being a constant.

·         Your blood. Again this is fairly constant, even if you donate blood, that which is lost will be replaced.

·         Skeletal muscle, this is the muscle that attaches to your bones to provide movement, heat and storage and the weight of it can vary significantly based on how full it is of glycogen and how hydrated the muscle cells are. The amount of muscle you carry can be increased in size and or density with the appropriate strength training programme, it can also be reduced in size due to a lack of activity, extended periods of severe calorie restriction or muscle wasting diseases.

·         Body fat, this can be further divided into 3 sub-groups,

1.       Visceral fat, which is the fat that is distributed around your internal organs,

2.       Subcutaneous fat, which sits under the skin,

3.       Intramuscular fat, this is distributed through the muscles and is what butchers call marbling on steaks.

Unfortunately, fat has an almost limitless storage capacity and is the primary storage space for excess calories that are left over once the body uses what it needs to run organs/ repair and grow skeletal muscle

·         Water content, the more hydrated you are, the heavier you will be. As you move through the day, hydration levels change, from sweating to fluid lost through respiration. Your carbohydrate intake affects hydration levels too as 1 gram of glycogen binds to 2-3 grams of water (this links back to skeletal muscle) so depleting glycogen also comes with the effect of reducing muscle cell hydration and is the fastest way to lose weight, but is often temporary. Of course the subject of hydration is fairly complex and I will leave that for another article.

·         The physical weight of the food you have eaten. This sounds like a no brainer, but it’s often completely over looked. When you eat food, it has mass; this mass has now been added to yours.

·         Faecal waste and urine, I know, gross! But the waste product of what we eat has mass and whilst that is sitting in your large intestine waiting to be passed, it’s contributing to the number on the scale.

 So as you can see, relying on a number on a scale is severely flawed, and ultimately slight changes in any of these can alter that number by as much as 2-3 kg daily. As a result it’s easy to become upset when the number isn’t what you want it to be, despite all your hard work. Even worse, the number on the scale can often lead to low self-esteem and therefore disordered behaviour towards food and exercise which often manifests in a destructive cycle of dieting/ binging.

Q. So how do I lose weight?

            A. You have to create a calorie deficit.

 It really is that simple, I know there are diet books out there that tell you it’s about hormones, or sugar, or fat , or whatever evil food it’s trendy to pick on, but the be all end all of weight loss is eating less calories than you expend. But as we discussed, weight loss doesn’t always come from body fat. Where it gets a little more complex is when medical issues come into play, autoimmune disease, hypothyroidism and insulin resistance are just a few, but people with these issues fall outside the scope of this article. So for arguments sake, we’re talking about people with no medical problems.

 Below are popular methods of creating a calorie deficit.

 1.       Meal replacement shakes. . Where meal replacements are involved, you don’t lose weight because of some magical property of the shake that you are now taking, despite the so called science they use to sell it to you. The simple fact is, you’re now consuming 150-200 calories, where before you were consuming 500+.  They are also woefully under dosed on protein and rely on cheap sugars to bulk out the shake and make it palatable, the results with these products are fairly instant, but it isn’t body fat that comes off initially it’s water weight, then a little bit of fat comes off and alongside it, lean muscle tissue, which once you get down to your desired weight, now means you have a massively reduced metabolism and returning to normal eating patterns will see your weight sky rocket back to where it was, only this time, with a much higher percentage of body fat! So what you do then is exactly what these companies want you to do, buy their products and start the whole cycle again, lining their profits and learning nothing about sensible eating habits.

2.       Long duration cardio workouts (often combined with meal replacement shakes) where you focus solely on how many calories you burn combined with some token dumbbell curls and kickbacks using less weight than the bag you carried into the gym! Of course you will lose weight, you’re creating a calorie deficit, but your shape won’t change too much. You will get the Skinny fat look. In other words, you will be slim by virtue of losing weight, but you will still have a fairly high body fat percentage. (The downside of which will be discussed in the 2nd part of this article.) Eventually you will hit a plateau, where, no matter how many hours you spend on the treadmill, nothing seems to work anymore. This is where we see a large majority of gym members do one of two things, cancel their membership and leave, disheartened that nothing works for them. Or assume that more equals better and sign up to every class going. Either way, they never quite get to where they want to be.

3.       Reducing specific food types from your diet. Sugar is the latest in a list of foods that are supposed to cause obesity, so the advice now is to reduce or eliminate refined sugar in your diet. There are numerous anecdotal accounts of sugar reduction leading to weight loss; however, unless these people were simply eating spoonfuls of sugar from the bag, they are also reducing calories from other sources too. For example a Mars bar contains 25.7g of carbohydrates, of which 20.8 grams are refined sugar, alongside those 20.8 grams comes 6.1grams of fat and only 1.1 grams of protein.  Overall, by not eating the Mars Bar, they are taking 165 calories out of their diet. So eliminating the refined sugar also comes with the elimination of all the excess calories that are in the food alongside it, therefore, creating the calorie deficit that causes the weight loss.

4.       Becoming a vegetarian or vegan. As with sugar, the weight loss that comes from switching lifestyles is nothing to do with magical fat burning properties of vegetables, but everything to do with no longer eating calorie dense meats, or in the case of vegans, dairy and eggs too.

 Q. What is a calorie?

            A. A calorie is a unit of measurement, it is the amount of energy required to raise the temperature of 1 gram of water by 1 degree

 You may have heard of the phrase, empty calories? With the exception of alcohol (which contains 7 calories per gram and is metabolised straight away as it cannot be stored and has no nutrient content), this is actually an inaccurate statement, food has calories, calories are units of energy, and therefore what you consume gives you energy. What someone really means when they say this food is just empty calories is that you are consuming food with little to no micronutrient value. However, not everything has to be full of micronutrients, if you are eating a balanced diet, where the majority of the food you consume is full of vitamins and minerals; the occasional treat does absolutely no damage to your health or fat loss goals.

 Q. I heard someone say that a calorie is not a calorie, is this true?

A. No, absolutely not, especially in the context that a calorie is simply a unit of measurement. It would be like saying a meter is not a meter.

 The statement is often made when trying to deny that energy balance is king when determining weight loss, it is true however, and that not all macronutrients are equal and this comes down their specific thermic effect (how many calories the body uses to process them) and the hormonal response they have on the body. Food is composed of different macronutrients, these are;

·         Protein, which is broken down into amino acids

·         Fats, these break down into lipids

·         Carbohydrates, these are foods that contain chains of glucose, and can be split into different categories,

1.       Monosaccharide which is a single glucose molecule, a refined sugar.

2.       Disaccharides, two glucose molecules

3.       Polysaccharides, more than 3 glucose molecules

4.       Oligosaccharides, these are a polymer of between 3 and 9 monosaccharides and commonly referred to as fibre

 Protein has the highest thermic effect in that it takes the most amounts of calories to break it down into its amino acids. A gram of protein contains 4 calories.

 Carbohydrates come next and the more complex the chain of sugars, the more energy the body uses to break it down into glucose, fibres are often indigestible, and therefore, the calories contained in them do not get used by the body for energy. Carbohydrates are 4 calories per gram.

 Fats have the lowest thermic effect, requiring the least amount of energy to digest, but yet they yield the highest calorie content of the 3 macronutrients at 9 calories per gram.

 When you build your diet, it is essential to consider how you want your body to look and then how active you are in order to proportion your calories to achieve this. Knowing your body composition is the first step towards doing this.

Q. What is body composition and what does it mean?

A. Body composition is the distribution of tissue type for a given weight, and is the defining factor in how you look, in or out of clothes and how you look compared to someone of the same weight. In other words, how much body fat versus how much skeletal muscle you are carrying.

 As discussed, you now know what your weight consists of.

 So, what kind of weight do you want to lose?

 I know this question sounds a little strange, but some people never actually sit down and think about this, they just want to weigh an arbitrary number without giving consideration to body composition.

 To determine this, we have several methods at our disposal.

  Tape measure. Simple and effective. Take circumference measurements of your shoulders, chest, waist, hips, thighs and arms. These are easily tracked and changes can be recorded giving you a history that you can compare current results with.

·         Skin-fold callipers, a slightly more advanced method of measurement, these are taken at different point of the body giving you an idea of the thickness of skin at that site. Some coaches use these to establish body fat percentage; however, the accuracy varies and can’t give you a figure for intramuscular or subcutaneous fat.

·         Bioelectrical Impedance Analysis (BIA). This is simply a measurement of how fast certain electrical frequencies travel through the body. The speed of signal is measured and your fat percentage is determined based on that signal speed. The accuracy of this method varies significantly due to factors such as hydration, how much food and waste you’re carrying, medication, caffeine and a whole bunch of other stuff.

·         Hydrostatic weighing. This was the gold standard for a long time and is based on the principle that fat mass has a different density to lean mass. You are weighed in a sling out of water, and then weighed in water. The difference in numbers is used to calculate your body fat mass. (1)

·         BodPod, A similar principle to hydrostatic weighing but relying on the displacement of air, rather than water. It takes less time and you don’t need to get wet.

·         DEXA scan. The new gold standard for body composition analysis. Basically you are x rayed at a specific frequency, from this scan, the technician can see how much body fat you are carrying and where it is distributed, how much skeletal muscle mass you have and your bone density.

 Because body composition differs from person to person, there is no one size fits all diet. And so you need to tailor your plan specific to you and your goals. For example, two men with different training habits that weigh 100kg, where one has 30% body fat and the other has 12% will have a completely different look and also completely different nutrition requirements. To put both men on the same diet will ultimately set them up for failure. This is where mass market diet systems fall short. They don’t account for your individual circumstances.

 I briefly mentioned training habits and this has a big impact on your dietary requirements too. The more active you are, the more calories you need to consume. In part 2, I will discuss this further and how to figure out your calorie requirements to tailor your nutrition for your specific goals.

Q; What about my BMI?

          A; BMI is not relevant as it does not take body composition into account. A rugby player with athletic ranges of body fat and a large amount of muscle mass, would, by BMI standards be considered obese. However, it shouldn’t be ignored completely as it is a good starting point for general populations.



(1)    https://en.wikipedia.org/wiki/Hydrostatic_weighing