“知己知彼, 百战百胜”
[zhī jǐ zhī bǐ, bǎi zhàn bǎi shèng]
“Know thy self, know thy enemy. A thousand battles, a thousand victories.”
-Sun Tzu, The Art of War
Depending on one’s fitness goals, the problem of extra subcutaneous fat can range from a “nice to have” to a full scale panic attack.
This article focuses on the amelioration of the aforementioned subcutaneous fat condition. Prior to that, a fundamental understanding of fat absorption in the human body needs to be established, all of which have been laid down in the previous article:
- Fat absorbed in the body is processed into glycerol and fatty acids.
- Fatty acids are converted into acetyl CoA, fuel for the body’s metabolic functions.
- Excess acetyl CoA is converted into fatty acids in the liver and stored in adipocytes in the form of fat.
From a strategic standpoint on ameliorating the excess fat storage condition, factors to take into consideration would include the regulation of the amount of acetyl CoA in the body, as well as the food sources from which the substrate is derived from. To be able to formulate a strategy to overcome such a problem, one must first understand carbohydrate metabolism and how the process ties into the condition of excess adipose tissue, which will be expanded on briefly.
Many carbohydrates present in food as sugars. These sugar molecules are broken down during digestion into monosaccharides (glucose, fructose, etc.) by enzymes in the digestive tract (a better known example being amylase, which is present in saliva), then absorbed in the small intestine and passed into the bloodstream. For its primary energy source, the focus on carbohydrate metabolism lies on glucose, which is utilized by organs such as the brain, or metabolized by red blood cells. The excess glucose that does not get absorbed into cells, is converted into glycogen and stored in hepatic and muscle cells [1].
Glucose in the bloodstream is taken up by cells in the presence of insulin. When absorbed into a cell, glucose molecules undergo a process called glycolysis. In this process, the glucose molecule undergoes many changes, but all of which culminate in the production of two pyruvate [C3H3O3] and four adenosine-triphosphate (ATP) [C10H16N5O13P3] molecules. A more in depth explanation of the lengthty chemistry can be found here: [2].
The aforementioned pyruvate is further processed in the cell mitochondria. The pyruvate is acted upon by the pyruvate dehydrogenase enzyme, which converts it into acetyl CoA and releasing carbon dioxide in the process. The acetyl CoA is then utilized in the Citric Acid Cycle [3] (Krebs cycle and TCA cycle being different names for the same process) to generate energy for cellular metabolism (via the breaking down of ATP into ADP (adenosine diphosphate). The full cycle can be seen here: [3]).
By now, an obvious relation can be drawn between carbohydrate and fat metabolism; which is the acetyl CoA that is used in the Citric Acid Cycle. From here, with the knowledge accumulated from carbohydrate and fat metabolism, a strategy can be formulated to help begin the process of fat loss.
A reasonable strategy to begin fat loss would be to reduce the amount of fat stored in the body in the first place. A good initial plan would be to reduce the amount of excess triglycerides in the first place, which working backwards would implicate the reduction of fatty acids and glycerol, and taken a step further would mean the reduction of un-utilized acetyl CoA in the body. In laymen terms, this would mean reducing carbohydrate/fat intake, or increasing the amount of exercise being conducted.
With the first strategy in place, it is possible to up the ante even further by increasing the amount of energy that the body obtains from fat. This would involve re-programming the body to obtain acetyl CoA from the breaking down of fat into fatty acids and subsequently the aforementioned by-product. Even though both carbohydrates and fat are ultimately converted into acetyl CoA to be metabolized, glucose is still the preferred source of fuel for more organs in the body (such as the brain and red blood cells). With that in mind, the key factor here is to reduce the blood glucose level to a point where the body is forced to extract triglycerides from adipose tissue to be broken down into fatty acids and subsequently acetyl CoA to fulfill the body’s energy needs.
One of the more popular practices that can be adopted to accomplish this goal include macronutrient management by balancing carbohydrate and fat intake to match one’s bodily metabolic demands. Another popular approach nowadays is the fat-based ketogenic diet, which focuses primarily on deriving all body metabolic needs from fat alone. An easier diet change would be the adoption of intermittent fasting, which places emphasis on depleting the body’s glycogen stores (implicitly reducing blood sugar level) to create windows of time where the body draws energy from fat stores. To top that off, one can further accentuate the merits of intermittent fasting by training in a fasted state, which accelerates the depletion of glycogen stores and encourages the body to convert more fat into energy.
Author’s note:
Before beginning any intense fat loss regimen, I advise that you try out various strategies for 1-2 weeks each, and recording the progress and side-effects for future reference. I also highly recommend consulting a physical therapist or fitness coach for their input on the matter, as every person may react differently to various fat-loss strategies. For example, intermittent fasts work much better for me compared to ketogenic diets when I’m aiming to lose weight, but others may differ. Some people may find that training is a fasted state is impossible, some may feel no effect, ultimately it affects everyone differently, so take your time and find what works for you.
The key here is to understand the underlying mechanics behind fat storage, followed by trying out different strategies to overcome it and seeing what works best for you. After that, it’s a matter of implementing what works best and seeing the results manifest. If you’re going to lose weight, you may as well enjoy the process.
Recap
The body draws energy for metabolic processes from the citric acid cycle, where the primary fuel is acetyl CoA. Acetyl CoA can be obtained from carbohydrates through pyruvate which is obtained from glycolysis of glucose molecules. The same product can be obtained from fatty acids (through beta oxidation) which are derived from triglyceride (fat) molecules.
Excess acetyl CoA is converted to fatty acids, which are then stored in the form of triglycerides in adipose tissue. Since the number of adipose cells remains constant in adults, therefore stored triglycerides only enlarge their cellular volume. From a macro-biological standpoint, this process serves as a means to store excess fuel for bodily metabolic processes in the form of fat (triglycerides). However, this process is also a double edged sword; the bloated adipose tissue being a symptom of obesity and a source of health complications down the line.
Many strategies can be developed to ameliorate the problem, but their underlying principle is the same: reduce the fat storage in adipose tissue, and obtaining energy for bodily metabolic demands from fat. These include more exercise, ketogenic diets, macronutrient management, intermittent fasting, and training in a fasted state.
Understanding the mechanics of fat storage is key to finding a strategy to overcoming it. Good luck and have fun finding what fat-loss method that works best for you, and have fun while doing it.
I do plan to go into each method individually in the future, so stay tuned for that.
Have a nice day!
References:
[1] Gylcogenesis, Virtual Chembook, Elmhurst College, 2003.
[2] Carbohydrate Metabolism, Anatomy and Physiology Textbook, Rice University.
[3] Krebs (Citric Acid) Cycle, Microbiology Info.com.
[4] The Science Behind Fat Metabolism, Will Little, KetoSchool, 2016.
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