Written by Dr. Folusha Oluwajana

What is body fat?

The term body fat refers to the percentage of fat in your body. Body fat in addition to bone, muscle and water determines your body composition and your overall weight. 

Why do people care about body fat?

There are two main reasons why body fat percentage gets so much attention; aesthetics and health. 

Your body fat is distributed between two major areas of the body. Your subcutaneous fat is the fat between your skin and underlying muscle; the fat you can pinch. Then there is your visceral fat, this fat lies within your abdomen surrounding your organs. 

The lower your body fat percentage, the less fat you have overlying your muscles. The less fat you have overlying your muscles, the more visible your muscles are. This is what gives you a leaner, toned physique or maybe even a visible “six pack”. 

The higher your body fat percentage, the less toned you will look and more fat you have surrounding your organs, visceral fat.  This is associated with a higher risk of certain health problems, such as type 2 diabetes, high blood pressure, heart disease, stroke and certain cancers. This risk is even higher if most of your fat is stored around your waist.

High body fat is usually associated with being overweight but this is not always the case. Slim people with higher body fat percentages and lower muscle mass are sometimes (perhaps not correctly) referred to as “skinny fat”. They have little tone or muscle definition and high levels of subcutaneous and visceral fat. They may not look how you expect unhealthy people to look, but even with a normal weight/BMI is normal (or low), if you have a high body fat percentage you still have a higher risk of disease. 

How can you tell what your body fat percentage is?

To accurately calculate your body fat, you’ll need access to pretty high tech medical and scientific equipment. The gold standard method is a DEXA scan, which uses X-rays to scan your body and determine all your body composition measurements. You can get these scans privately, at a cost.

A much more inexpensive method, and likely the oldest way of measuring body fat, is the skinfold calliper test. A pair of callipers, like big tweezers, are used to measure skinfold thickness in different areas (the fat you can pinch) to estimate your body fat percentage. The reliability of the result however relies a lot on the tester,, but highly skilled testers can produce accurate results. 

Then there are the body fat scales. You often find these in gyms and clinics, and you can even buy these scales at home. They use bioelectrical impedance, a small electric current that runs through your body when you step on the scales that estimates your body fat percentage. Higher end models may even have sensors that you hold on to as well as step on which may be more accurate. But overall, these scales are not the most reliable way of measuring body fat. 

What is a good or bad body fat percentage?

Body fat levels vary depending on several factors. The two factors you cannot change are your sex and age. Men tend to have lower body fat levels than women, so the spectrum is different between the two. In addition, as we age body fat levels naturally increase. 

Body Fat Percentages for Women

Body Fat Percentages for Men

How can you change your body fat percentage?

When most people talk about losing weight, they really mean losing body fat, in order to look leaner and toned. (Don’t forget to look toned, you have to have muscle to reveal underneath your body fat!)

To lose body fat you need your body to use up your excess fat stores as fuel. This is done by burning more energy than you take in, or burning more calories than you take in, also known as a calorie deficit. By changing your diet to reduce calorie intake and doing more physical activity to burn more calories, you can create a calorie deficit, leading to fat loss. 

On other hand, muscle mass is increased by stimulating muscle growth. This requires stimulation by resistance training and increased calorie intake to create the new muscle. To really build muscle, you actually need to eat more. 

Fat cannot be converted to muscle or vice versa. Muscle and fat cells are completely different units, they have different DNA, structures and functions. In fact, you actually never really lose fat cells. When you lose body fat, fat cells shrink in size, they do not disappear and when you gain they increase in size.

There is also a process called body recomposition. Body recomposition is the process of building muscle and losing fat at the same time. It isn’t easy because the processes for losing body fat and building muscle are direct opposites, and it is a slow process but it can be successful in some situations. It is usually easier for beginners or those with higher body fat levels. You have to be spot on with your training, optimise your nutrition and recovery and be patient. If you are more trained and experienced, you may find it easier to change your body composition by engaging in distinct periods of gaining muscle (bulking and increasing calorie intake) and losing body fat (cutting and reducing calorie intake). 

So is your body fat percentage important?

Yes…and no. 

Measuring your body fat (and weight) can be helpful to monitor progress, your health and make decisions about your diet, training and lifestyle. However, solely focusing on numbers can become restrictive and for some, obsessive. Your body fat doesn’t reflect other important markers of progress. Increased strength, fitness, better mood and energy, how your clothes fit and how you feel when you look in the mirror, your self confidence, self esteem and happiness. 

Maintaining very low body fat percentages can be difficult. Your diet may become very restrictive in order to avoid body fat gain and over exercising becomes more common in this situation. There is a risk of developing disordered eating and exercise habits in some individuals.  In women, fat is a major site of hormone production and very low body fat levels can lead to abnormal hormone production impacting your menstrual cycle and leading to irregular or complete loss of your period. This is known as hypothalamic amenorrhoea. Consequences of this include impaired fertility and reduced bone density and fractures.  

Ultimately, having a certain body fat percentage will not necessarily make you happy, or healthier. It’s probably not that useful for most people to monitor body fat percentages in isolation, and reliable monitoring devices are not that easy to access.  It is best used wisely as a source of information, amongst many other markers of progress, to improve your health and change your body and lifestyle.