Science of Fat Loss: What is Fat?
Science of Fat Loss:
What is Fat?
Fat - it’s what most people in the fitness industry want to see less of on their bodies, but what even is fat? Where and how is it stored? What do we need it for? In order for us to understand fat loss, it's important to go through some background information first, like what fat is and what it isn't.
To begin with, when we say fat we are generally referring to it in two different contexts:
Dietary Fat
Dietary fat (the fat that you eat) is a macronutrient that your body needs as a major source of energy (along with carbohydrate and protein, which will be covered in a later post). Dietary fat also plays a crucial part in the health of your body’s cells as well as:
Production and balance of certain hormones (particularly testosterone and estrogen)
Efficient absorption of nutrients (particularly fat soluble vitamins like vitamin A and D
Provides your body with Omega 3 and 6, which your body can’t make on it’s own
There are 3 main types of dietary fat: unsaturated fats, saturated fats, and trans fats.
Unsaturated Fats:
E.g Avocados, olive oil, fish, seeds, nuts
This is where you can get omega 3 and 6 from (your body can’t make this on its own). These keep your brain cell membranes healthy, which mean neurotransmitters like serotonin can be received in the brain more easily. It also helps with brain development and to slow degenerative brain disease.
Saturated Fats:
E.g Coconut, meat, butter
These have a history of being viewed as unhealthy, but current research supports that you can include saturated fats as part of a health-promoting and well-rounded diet.
Trans Fats:
E.g Heavily processed food
These don’t occur naturally most of the time. These are fats that are created through industrial processing and is commonly used for commercially baked products like cookies, pies, donuts, etc.
This artificial process isn’t received well by your body. Unlike normally occurring fats (like unsaturated and saturated fats), trans fats don’t get recycled in the body. They create a build up of LDL (low density lipoproteins, often called the ‘bad’ cholesterol) in your arteries. Over time, this build up is known to increase your risk of heart disease.
In 2015 the FDA announced that they are not recognised as safe and will need to be phased out of production.
Dietary Fat Tips:
Dietary fat has an important role to play in the function of our bodies, so it’s generally not a good idea to cut them out of your diet completely. In a later post, we’ll be analyzing some of the low-fat, fad-diets that you may have heard of and talk through pros and cons of a diet like that. For now, here are some tips to getting a healthy balance of dietary fat in your diet, whether you’re looking to lose body fat or not.
Around 30% of your daily energy intake should come from dietary fat for a balanced diet (that’s about 3 thumb sized servings of fat per day)
Minimise processed foods and choose whole food options
Read labels - although not all processed foods name trans fats on the label or ingredients list, so minimising processed foods is a good general guide
Substitute snack options for nuts, seeds, or a little bit of dark chocolate. Nuts and seeds in salads will add variety in nutrients, but also provide added taste and texture to your meals
Use a variety of cooking oils - extra virgin olive oil, coconut oil, and avocado oil are great options that add flavour to your meals
Body Fat
Body fat is one of the many ways our bodies store energy that we get from food. It also surrounds and cushions vital organs like the kidneys and insulates us against the cold. In our evolutionary history, survival depended on being able to store energy around the body as access to food was so unpredictable. Our ancestors faced long periods of time where food wasn’t readily available, for example - harsh winters, hunting and gathering seasons, and food crop failures. Being able to store energy in our bodies meant that we could survive for longer. While there are other forms of stored energy which we will cover in later posts, let’s talk through fat storage first.
THE PROCESS OF FAT STORAGE
Fat is made up of triglycerides which are three fatty acid chains attached to one glycerol ‘backbone’, in the shape of an “E”.
Triglyceride - three fatty acid chains attached to one glycerol ‘backbone’, in the shape of an “E’.
When fat is consumed, an enzyme called lipase breaks down triglyceride into it’s smaller components (glycerol and fatty acid chains) in the small intestine. These small components are absorbed into the bloodstream and then go through various processes to be reassembled as triglyceride and stored in our ‘adipose tissue’. Adipose tissue is distributed all over your body and is where your body stores fat to be utilised in the future as fuel.
When your body needs to use this fat store, it will break down the triglyceride back into the smaller components to be absorbed by the liver and muscles. The liver absorbs the glycerol and muscles absorb a majority of the fatty acids. Once absorbed in those locations, those smaller components are broken down further into ‘acetyl-coa’ which is the starting substance for important processes like the ‘Citric acic cycle/Kreb’s cycle’. This is what turns those triglyceride components into usable energy.
It’s worth mentioning that the body doesn’t only store fat from the food we eat. The liver goes through various processes to make fat to store as well from proteins and carbohydrates. These additional fats are made to enable the easy storage of energy in fat cells and help to explain why a low-fat diet won’t necessarily result in you losing body fat.
So How much body fat to you need?
How much is healthy or Unhealthy?
While starvation is less of a problem for the modern world now, having some fat stores is still essential for us to live. Having too little body fat is known to negatively impact health (even resulting in death) and having too high body fat is known to negatively impact health as well. The two ends of the spectrum are known to contribute to lower health and quality of life, but it is between these ranges that there is some controversy to what levels of body fat are better or worse (usually seen as a percentage of bodyweight).
Body Fat Percentages
While there are disagreements on what specific levels are better or worse, there are generally accepted ranges for health. Below are two generally accepted body fat percentage charts that specify ranges. In general, men have a lower body fat to lean tissue ratio than women (reproduction plays a role in the higher body fat percentages for women), which helps explain why there are differences in ranges for men and women.
Percentages for Men:
The American Council on Exercise (ACE) has a body fat chart that categorises the following ranges for men:
Essential fat for men: 2-4%
Athletic range for men: 6-13%
Fitness range for men: 14-17%
Acceptable range for men: 18-24%
Obese range for men: Over 25%
The Beth Israel Lahey Health Winchester Hospital gives the following guidelines for a healthy body fat percentage for men based on age:
Age 20-39: 8-19%
Age 40-59: 11-21%
Age 60-79: 13-24%
Percentages for Women:
The American Council on Exercise (ACE) has a body fat chart that categorises the following ranges for women:
Essential fat for women: 10-13%
Athletic range for women: 14-20%
Healthy range for women: 21-24%
Obese range for women: Over 32%
The Beth Israel Lahey Health Winchester Hospital gives the following guidelines for a healthy body fat percentage for women based on age:
Age 20-39: 21-39%
Age 40-59: 23-33%
Age 60-79: 24-35%
Percentages are perhaps a more relevant way of measuring health as compared to BMI which only considers height and weight (not how much of that weight is fat versus lean muscle). There are still limitations with body fat percentages though as getting an accurate and consistent measure requires a trained professional such as a trainer or nutritionist (who is trained with skin fold callipers) or with technology which typically costs more or is just not available, for example:
Dual-energy X-ray absorptiometry (DXA)
Hydrostatic weighing
Air displacement plethysmography (Bod Pod)
3-D body scanners
The Bottom Line
Fat is very important to our bodies and shouldn’t be demonised, even when we’re looking to reduce the amount of fat that is stored in our bodies (a tricky balance that we’ll talk about in a future post)
You need some fat stored in your body - not too little, not too much (much like everything else in life)
Body fat percentage can be more helpful than BMI (though looking at the whole picture of health is always more helpful than fixating on any one number)
Aim to include a variety of dietary fats in your food intake
UP NEXT → Metabolism and Energy Balance
During adolescence, the amount of fat cells in your body becomes ‘set’ and remains unchanged throughout the rest of adulthood. This means that fat cells do not disappear but instead are shrinking and expanding depending on the amount of energy our bodies are using or storing.
This largely depends on the energy balance that your body is maintaining. We'll be going over this in our next post so stay tuned!
If you are wanting some guidance or help with fat loss or nutrition as a whole, please don’t hesitate to reach out!
Our qualified nutritionists are more than happy to help.
Authors: Ian Yang (ONI Nutritionist) and Laurent Pang
ONI Personal Training | Massage Therapy | Nutrition Coaching | Movement Coaching