24th Aug 2021

Understanding Body Composition

Understanding Body Composition

When you’re thinking of losing weight or just need to examine however healthy you are, you’re most likely to do one of these 2 things: tread a scale or calculate your BMI. However, we often fail to realize that these two methods are not exactly enough to tell you how healthy you are.

As you get healthier, you’ll most likely lose fat and gain muscle. In order to differentiate between muscle and fat, it is imperative to keep in mind your body composition.

By understanding your body composition, you gain a deeper understanding of your overall health and can focus on making progress that goes beyond just the number on the scale.

Body composition analysis is a method of describing what your body is made of, understanding the difference between fat, protein, minerals, and body water to give you a clearer picture of your health as your body composition can be influenced by numerous factors like age, sex, genes and hormones.

If you’re looking for an easy way to understand your body composition, worry not! Read on to find out the various factors involved that can help you achieve your health goals from the inside out.

The definition of body composition is ‘the percentages of bone, fat, water and muscle in human bodies’.

Two people of the same sex and body weight may look completely different from each other because they have a different body composition. Using this analysis, you can set goals for risk prevention and/or to keep your body in balance. Taking all these components into account gives a much more accurate approach to gain an insight into one’s physical health and gives a broad range of information about the state of a body.

A woman stepping onto a scale


Body Mass Index (BMI) is an index of weight-for-height that is commonly used to classify underweight, overweight and obesity in adults. In its most basic sense, BMI may be useful for identifying those who are at an increased health risk because of excess fat accumulation. Analysing your health using a single number such as BMI oversimplifies health risks and ignores the other important factors like if any changes in your weight are in fat or muscle. That’s because BMI is calculated simply by dividing a person’s weight by their height. The BMI categories shown in the chart and table below are recognised by the WHO (World Health Organisation) and can be used to interpret your BMI value. 

Body Mass Index chart


The human body is made up of, amongst other things, a percentage of fat. This is vital for a healthy, functioning body – it cushions joints and protects vital organs, helps regulate body temperature, stores vitamins and helps the body sustain itself when food is scarce. However, too much body fat or indeed too little body fat can be damaging to your health. It is difficult to gauge how much body fat we have in our bodies simply by looking at ourselves in the mirror. This is why it is important to measure and monitor your body fat percentage. Body fat percentage gives you a better measure of fitness than weight alone – the composition of your weight loss could mean you are losing muscle mass rather than fat – you could still have a high percentage of fat even when a scale indicates ‘normal weight’.

Body Fat Percentage Chart


Body water is the single most important component of body weight. It represents over half of your total weight and almost two-thirds of your lean body mass (predominantly muscle). Water performs a number of important roles in the body. All the cells in the body, whether in the skin, glands, muscles, brain or anywhere else, can only function properly if they have enough water. Water also plays a vital part in regulating the body’s temperature balance, particularly through perspiration. The combination of your weight and fat measurement could appear to be ‘normal’ but your body hydration level could be insufficient for healthy living.

For those using Athlete Mode: please note that athletes may have a lower body fat range and a higher body water range, depending on their type of sport or activity. Body water measurement results are influenced by the proportion of body fat and muscle. If the proportion of body fat is high, or the proportion of muscle is low then the body water results will tend to be low. It is important to remember when using body water scales that measurements such as body weight, body fat and body water are tools for you to use as part of your healthy lifestyle. As short term fluctuations are normal, we suggest you chart your progress over time, rather than focus on a single day’s reading.

Body Water Chart


According to the American College of Sports Medicine (ASCM), lean muscle mass may decrease by nearly 50 percent between the ages of 20 and 90. If you don’t do anything to replace that loss, you’re losing muscle and increasing fat. It is also important to know your muscle mass percentage during weight reduction. At rest, the body burns approximately 110 additional calories for each kilo of muscle gained. Some advantages of gaining muscle mass include:

  • Reversing the decline in strength, bone density and muscle mass that accompanies age
  • Maintenance of flexible joints
  • Guide weight reduction when combined with a healthy diet.


Your Basal Metabolic Rate (BMR) is an estimation of the energy (measured in calories) expended by the body, at rest, to maintain normal body functions. This continual work makes up about 60-70% of the calories the body uses and includes the beating of your heart, respiration, and the maintenance of body temperature. Your BMR is influenced by a number of factors, including age, weight, height, gender, dieting and exercise habits.

A doctor showing a patient something on a laptop screen


A healthy balance between fat and muscle is important for a healthy lifestyle. Scientific evidence shows that a healthy body composition will increase your lifespan; reduce the risk of heart disease and improve your self-esteem.

If your body fat percentage is too high, attempt to decrease it to improve your health, wellbeing and athletic performance. However, if you notice your body fat percentage to be below the threshold, you may want to make certain changes in your lifestyle to bring it to that level thereby reducing your health risks. So, to improve your body composition for better health and fitness, aim to increase muscle mass and decrease excess fat mass. To do this, you can change your diet, start an exercise program, or combine both the methods for effective results.

Salter has a range of Body Analyser Scales that not only measure your weight but also help you understand your body composition thereby giving a more accurate measure of your overall health and fitness.