Targeted Fat Loss: Myth Or Possibility
One of the most popular myths in the fitness industry is the famous fat spot reduction. This idea suggests that certain exercises (sometimes in combination with certain foods) can lead to targeted fat loss in wanted areas like the legs, stomach etc. All this sounds very tempting but is it true?
Short answer – targeted fat loss is not possible. In the following article every single aspect of this myth will be explained so if you want to lear the science behinde it I invite you to a 5 minute read.
What is fat?
Fat tissue is a special form of connective tissue whose cells can store fat, i.e. triglycerides. While storing fat, the cell grows and expands and the triglycerides form little bubble-like structures which give a grainy appearance to the tissue. The most important trait of fat cells is that their number (in the adult age) can't be decreased. Depending on the amount of triglycerides stored in its inner structures the cells can expand or deplete but the number of cells does not decrease (that’s why people that were always lean aka. at a lower body fat percentage their whole life can obtain and keep a lower body fat percentage easier). A new fat cells is formed only if the previous cell reaches its maximum storage capacity. The fat tissue that our bodies use as an energy reserve belongs to the yellow fat tissue group and the storage fats subgroup. Even though fats in the form of nutrients carry the most energy (calories, 9kcal/g), storage fats only have ¾ of that energy value because they contain other compounds in their molecules (carbs, proteins, minerals, water). The cross section of a fat cell shows two distinctive structures: a core and fat.
How do fat cells form?
As the name suggests storage fat could store excess and form reserves which the body can use to survive periods where it doesn’t get sufficient nutrients through food. Fat cells form from excess:
- When it comes to excess fats the process is simple and efficient. Fats consist of glycerin and three fatty acids which are in most cases different (3 fatty acids = tri(3)glcycerides). Because triglycerides are the type of molecules that fat cells can „accept “as a reserve, excess fats can simple be just „put into “fat cells.
- In the case of carb the process is much more complex. An excess of carbs, more precisely glucose (which is the main source of energy in the body and to which all complex carbs are transformed) must go through a couple of chemical transformations to get to the end state and for it to be stored in fat cells.
Glucose (glycolysis) > Pyruvate (oxidative decarboxylation) > Acetyl-CoA > Citrate (transport through mitochondria) > Acetyl-CoA (carboxylation) > Malonyl-CoA (fatty acid synthesis) > fatty acids
Forming fat out of glucose is a uneffective process for many reasons:
- A lot of energy is needed ( ¼ of the energy from the excess carbs goes into the transformation process itself)
- Activity of the enzymes needed in the transformation process is very low
- The oxidation limit of glucose increases with carb intake (to kick start the process of transforming carbs into fats the oxidation limit must be exceeded)
- All glucose (more precisely glycogen) storages in the body must be full (liver 10g/100g liver tissue, 1g/100g muscle tissue)
- The transformation process starts only if the carb intake exceedes 500g/day*
Why targeted fat loss isn't possible?
The idea of targeted fat loss is based on the believe that certain exercises for the “problem areas” can contribute or make fat in that are “disappear”. That would be possible if the main energy source for our body were triglycerides and not glucose. No matter which muscle or muscle group we train they get the same type of energy from the same sources. In the beginning they will use free ATP followed by glucose from the muscles and then the liver which means that the energy needed for the muscle to work comes from all parts and regions of the body and not only from the muscle that works.
The second problem lies in the “magic exercises”. We all know that if we want a flat stomach we need to do sit ups, right? Wrong! Isolation training where we concentrate on only one muscle or muscle group burns very few calories because the amount of work is not that big. It’s basic physics at work: the amount of energy needed depends on the amount of work done and work depends on the amount of force and distance. Because of that we will burn more calories by doing complex exercises that involve more muscles and larger muscles than we will burn by doing exercises that use only one muscle. We can also increase the amount of energy needed in two ways:
- Increasing force – increasing the amount of resistance that the muscle must work against by adding weight, increasing reps or sets etc.
- Increasing the range of motion (distance) – increasing the distance will also lead to higher energy expenditure because the muscle will have to cover a longer distance and therefore need more energy to do so.
It really all comes down to simple physics: mechanics and thermodynamics.
Genetics are another obstacle. Every person is different, and everybody will store reserves in a unique way. While some people store their fat mostly around their waist other will store it in the legs. Even though everybody has a “favorite” place to store fat, the excess fat will be stored around the whole body in smaller amounts (that’s the reason why we sometimes don’t see those extra 2-3lbs that the scale shows) which ensures that a small excess of body fat doesn’t cause major problems (when every single gram of fat would be stored around the waist, then every person with a slightly higher body fat percentage would have an increased risk of diabetes, heart disease because of the visceral fat**).
How to decrease body fat?
The right way of decreasing body fat is simple. You will have to force your body to use its reserves and that will be achieved through a small caloric deficit of around 200-400kcal (achieved through diet modifications) and doing complex exercises (squat, press, squat jump) to increase the daily energy expenditure.
When we say complex what do we mean? Complex exercises are exercises that involve more than one joint (for example squat: hip, knee, ankle) and activate more muscles. Muscles are the main and basic active consumers that we can influence consciously. The goal when trying to lose body weight and body fat is to activate our consumers (muscles), increase the heartrate and burn more calories than we take in. When that happens, the body will start to use its reserves and transform them into energy and the reserves will decrease. To lose 1lbs of body mass we will have to burn 3500kcal more than we take in.
*This is an estimate
**Visceral fat is fat that accumulates in the abdomen. In other words, it is known as "deep" fat that is kept far underneath the skin when compare to subcutaneous fat (just under the skin). Consistency of visceral fat is similar to gel and it is wrapped around the main organs, including the liver, pancreas and kidneys.