Losing body fat, is a common body composition goal – but the type of fat matters when it comes to health.
Why is fat important?
Fat, otherwise known as adipose tissue, is crucial for life and certain levels are necessary for full health. Levels of body fat for survival differ than those for optimal health, whilst too much fat can contribute to chronic inflammation and harm long term health.
Essential fat is found throughout the body – in the brain, organs, bone marrow and cells. Functions include: cushioning and protecting organs, providing crucial energy reserves and insulation.
Healthy levels of body fat are required for the presence of vital chemical substances (hormones) and messengers (neurotransmitters) throughout the body.
Storage fat is also a critical source of energy – necessary for every single process that takes place in the body. Fat is also the preferred energy source for lower intensity exercise.
Classifying fat tissue according to function…..
There are two main types of fat/adipose tissue, white adipose tissue (WAT) and brown adipose tissue (BAT).
WAT (white adipose tissue): is the primary site of energy storage. WAT secretes important substances which have hormonal and metabolic roles – regulating energy balance, food intake and appetite, the inflammatory response and the production of sex hormones such as oestrogen.
WAT also cushions, insulates and protects the body. It is the predominant type of fat tissue found in subcutaneous and visceral fat.
BAT (brown adipose tissue): is responsible for the non-shivering heat production that protects new born babies. It acts as a sink for the uptake of sugar and fat in the blood and generates energy in the form of heat – clearing up fat and preventing excess stores building up.
It is mostly located in the upper back, around the clavicles and the vertebrae.
Different fat cells for different functions?
WAT is made of WAT cells and BAT is made of BAT cells. There are another group of fat cells, beige or brite adipose cells which are in between WAT and BAT cells. These are found in WAT.
Where your store fat matters
The most commonly referred to categories are subcutaneous and visceral fat. However, there are other categories such as epicardial fat, which is the fat stored around the heart.
Found in the spaces between the skin and the muscles, throughout the whole body. If you are healthy and lean, WAT is the predominant type of fat, making up approx. 80% of all fat tissue.
It preserve heat loss, acts as a barrier against infection and provides cushioning. It can be separated into upper and lower regions and upper subcutaneous WAT is often lumped together with visceral WAT, classified together as abdominal fat.
Lean healthy individuals do not have much visceral fat. Visceral fat is predominantly found around the organs in the abdominal area, such as the liver, intestines and kidneys.
The accumulation of visceral fat comes can come from excess subcutaneous fat which essentially overspills.
This type of fat has become dysfunctional and secretes harmful substances that contribute to poor metabolic disease – from inflammation, to elevated levels of insulin and blood fat levels, and heart disease.
Why some people appear skinny but store visceral fat is likely due to a combination of reasons: poor diet and insufficient activity, genetic predisposition and low birth weight.
We all have different thresholds at which we’ve reached our fat store limits and this fat becomes harmful visceral fat. Additionally our capacity to store fat at different areas of the body plays a role.
How does what fat you have impact your health?
Visceral fat is associated with insulin resistance, predisposition to diabetes, inflammation, high cholesterol, high blood pressure and heart disease. This type of fat is dysfunctional, secreting harmful substances which affect the organs around it.
It is associated with being in a chronic inflammatory state and poor immune health.
This why when you are overweight, weight loss itself is associated with a reduction in levels of inflammation.
Does what fat you have matter more than how much fat you have?
Yes and no!
“Normal” weight individuals with visceral fat stores are likely to be unhealthy and be at increased risk of various chronic diseases, including heart disease.
Different ethnicities have varied susceptibility to accumulating visceral fat – the Asian race are particularly prone to accumulate intra-abdominal fat despite being at a “normal” weight.
This is why using body weight or body mass index (BMI) is often an insufficient measure of health. Instead, using a combination of waist circumference, waist/hip ratio, weight to height ratio are more informative.
However, visceral fat tends to be a result of too much subcutaneous fat. Fat (adipose) cells either grow in size or number.
When they grow in size, they can become dysfunctional –secreting harmful substances and subsequently creating a low grade inflammatory state.
It is thought that you may have a certain predetermined number of fat cells unique to you and if exceed the amount of energy that you can store (in your number of fat cells), your fat cells have no choice but to expand and overflow, resulting in the development of visceral fat.
Therefore how much fat you have matters, because if you have too much fat for you as an individual, then you will be likely to gain visceral fat.
How do I know if I have healthy levels of fat?
Waist measurements! Shown to be a great predictor of levels of visceral fat – if doing this yourself, remember to use reference ranges that consider your ethnicity.
You could use a waist to hip circumference ratio, also shown to be a strong predictor of visceral fat.
Standard body composition measurements such as a DEXA scan or BIA can also be used.
Here are also some general signs associated with unhealthy body fat levels – however, the body can take a while before it manifests symptoms and therefore checking in with a health professional (GP, registered dietician/ nutritionist) and/or taking the above measurements are key.
Additionally, these signs could be due to a different root cause and therefore I would advise against self-diagnosis.
Too high fat levels may be associated with: low energy levels, dysregulated appetite, ache and pain in the joints, discomfort when moving, low grade inflammatory state and a host of developing chronic diseases.
Too low fat levels may be associated with: fatigue, poor concentration, low energy levels, reduced libido, dysregulated appetite, frequently becoming ill, slow recovery, reduced levels of performance, feeling cold, irregular or absent menstrual cycles, osteoporosis and severe heart issues.
Both too high and too low body fat levels are associated with reduced life span.
How to reduce visceral fat:
Is about effectively manging your weight (for you) and being healthy through a consistent diet and exercise plan that is appropriate for you.
Follow a diet plan to create a calorie deficit: to lose excess fat stores. A moderate calorie deficit is best for promoting fat loss rather than muscle loss.
Consider a high protein diet: shown to have favourable effects on body composition even when calories are matched.
Do enough exercise for you: research indicates that the 150 minutes of exercise per week that is generally prescribed does not provide the same risk reduction for the Asian race as it does for the white US race.
Include a variety of exercise intensities: to benefit fat loss and overall health. Including both low intensity cardio and high intensity likely provide different benefits and may specifically benefit normal weight peeps with visceral fat stores.
Follow a progressive resistance training programme: to reap the variety of benefits from gaining muscle – increased metabolism, increased insulin sensitivity, reduced risk of chronic disease and increased lifespan.
Body fat is essential for life and optimal health: body fat serves multiple purposes – from the cushioning of organs, to being an important source of energy and being involved in the production of many critical substances involved in immune, metabolic, and reproductive health.
Where you store your fat matters: visceral fat, stored around the organs in the middle of the body, is associated with increased risk of chronic disease – cardiovascular disease, type 2 diabetes and insulin resistance.
If you are concerned about whether you have healthy levels of fat: speak to trained healthcare professional and/or gaining further body composition measurements to add insight.
You can reduce levels of visceral fat: through an appropriate nutrition, exercise and lifestyle plan that is right for you.
Chait et al. (2020). Adipose distribution, inflammation and its metabolic consequences, including diabetes and cardiovascular disease
Ikeda et al. (2018). The common and district features of brown and beige adipocytes.
Kapoor et al. (2021). Thin fat obesity: the tropical phenotype of obesity.