Body composition, as the term suggests, describes the proportions of fat, bone and muscle in the human body. In PerformancePro’s latest series of fitness insights, we guide you through the facts, myths and challenges in measuring body composition and therefore, fat levels. Then, in true PerformancePro style, we also suggest a way forward.
So, back to body composition and what it really means. Quite simply, two people of the same sex and body weight may look completely different because they have different body compositions (percentages of fat, bone and muscle).
The world has woken up to the life-threatening dangers of obesity and cost of treating the associated illnesses of being overweight. But, what exactly is ‘overweight?’
The F Word
Let’s talk about the F word, FAT.
Earlier we mentioned body weight. From a scientific and practical point of view, it is more useful to focus on the term body fat as opposed to the word ‘weight’. In an ideal world, decreasing body fat and increasing lean muscle mass is the healthiest and safest approach to take to improving your body composition and, therefore, quality of life.
As individuals, we are all predisposed to carry body fat in slightly different ways depending upon our genes and gender. Let’s spend a moment looking at the difference between visceral and subcutaneous fat.
Visceral fat describes the fat around our internal organs; heart, liver and inside the abdomen. Problems arise when this visceral fat reaches levels that impair the function of the organs it is meant to protect. It begins to restrict, clog and damage the structures vital to our survival. Excessive visceral fat has been linked to diabetes, heart disease, colon cancer and stroke.
Subcutaneous fat, the type beneath our skin, has different roles. It serves as stored energy, insulates us against the cold and helps protect us against impact. However, as with visceral fat, excessive subcutaneous fat has also been linked to diabetes, heart disease, colon cancer and stroke.
So how do we measure our body composition to ascertain whether we are carrying too much fat?
Measuring Body Fat and Body Composition
Currently, there are over 100 different algorithms or prediction calculations for assessing body fat. Most of us, however, only have access to a few methods ie. a trip to the research facility at NASA is out of the question!
- Bio-electrical Impedance Analysis (BIA) – This method usually uses the popular Tanita scales to estimate total body water (TBW) by measuring the resistance and reactance of tissues. From this, our fat free mass (FFM) and body fat is calculated.
- Callipers – Using a physical calliper that pinches and measures skin folds at various sites around the body, this method uses a predictive calculation to measure body fat.
- Ultrasound – This method uses a handheld device to generate an ultrasound signal that travels through tissue and records the reflected signal. In doing so, the ultrasound device measures the change in echo created as the signal hits the boundary of different tissue types, for example, fat-muscle and muscle-bone. Body composition is then calculated by measuring subcutaneous fat thickness at multiple sites
- DEXA Scan – DEXA (or Dual Energy X-Ray Absorptiometry) is regarded as the gold standard and most accurate of all methods as it directly differentiates between fat, lean mass and bone. By using X-rays, DEXA can see internal (visceral) and intramuscular fat as well as surface (subcutaneous) fat, so it genuinely measures your total body composition, not just fat levels. It also has the advantage of being able to assess visceral fats (internal fats) as well as subcutaneous fats (fat under the skin).
The truth about BMI
Body mass index or BMI is used globally to help with the general identification of risk factors associated with obesity. It uses a simple ratio between height and weight to give a number on a scale of low to high risk. This is then expressed as underweight, normal weight, overweight and obese to morbidly obese.
Where BMI falls down is that it is blind to actual body composition (ie, how much of your weight is from fat and how much is from muscle).
As we know, muscle weighs more than fat, so more lean mass than average can put you high on the BMI scale, when health-wise you’re likely to be a lower risk than someone with higher fat levels.
Take for example two men; Bill and Ben. Both are 6 feet tall, and weigh 95kg. Both men have a BMI of 28.37 so are considered overweight by medical standards.
However, Bill trains 4 days a week doing a combination of weight training and interval training, his body fat is 14% whereas Ben trains once in a blue moon, eats out and drinks more often than Bill. He carries around 20% body fat.
Which one do you think is healthier and at less risk of heart disease and diabetes?
The PerformancePro approach to measuring body composition
Clearly, we need more than our BMI when assessing overall health. We can add hip/waist ratio as an indication OR to be more accurate, we need to measure body fat percentage as part of overall body composition.
At PerformancePro, we use callipers and the slightly more scientific method of ultrasound. These two methods give us a useful starting point with a general measure of health.
When we need more, we work with our partners at Bodyscan, the UK’s leading authority on the use of DEXA X-ray technology to measure body fat composition.