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By Roland Pankewich

Read Part 1 HERE

Read Part 2 HERE

So far we have outlined some basic principles that determine fat loss; mainly that fat loss is a catabolic (to adipose tissue) process that is supported metabolically via mitochondrial beta oxidation (fat burning). To completely paint the picture we must examine the other side of the equation in factoring in how the endocrine system facilitates fat loss or fat storage, and what key hormones are necessary to regulate this process.

Hormones are fundamentally signaling molecules constructed in the body from nutrients we consume and released from different organs and glands. We have specific sex hormones: testosterone, estrogen, progesterone, and their derivatives. We have hormones of growth and regeneration like growth hormone and hormones of satiety/metabolism; insulin, glucagon, ghrelin, leptin. Finally, we have our catecholamine pathway which consists of norepinephrine, epinephrine, and cortisol. There are many more hormones that I left out, but given the scope of this article we are going to focus on the ones that have both most relevance and impact on body composition and metabolic activity.

Let us start with the two antagonists as they relate to blood sugar regulation as well as anabolic/catabolic activity; insulin and glucagon. I wanted to start off this analysis by saying that neither of these hormones is inherently good or bad, the perspective is all a matter of context. Rather they play opposite roles to regulate energy metabolism, and in the case of fat loss, timing is everything.

Insulin

Insulin is an anabolic hormone that is stimulated primarily by increases in blood sugar and in some cases protein/amino acids.  Insulin’s job is to stimulate the uptake of glucose into cells when blood sugar levels are elevated, and by association it can help facilitate the uptake of other nutrients; amino acids, fatty acids, and micronutrients.  All cells with insulin receptors respond to its signal and it is for this reason that insulin gets a bad rap in conversations regarding fat loss.

Fat cells, also known as adipocytes, also respond to the signal insulin sends, and when activated are primed to uptake fatty acids from either source: dietary intake or the conversion of excessive glucose into fatty acids.  What this basically means is that when we elevate blood sugar the whole body’s response is to become anabolic and “store” nutrients. When we eat excessive carbs, fat burning effectively shuts down because the body is flush with energy and it will prioritize glucose metabolism to form ATP (energy). Given this change in physiology, we can now understand why insulin can be contextually problematic as when fat burning stops, fat storing happens.

This basically means that if we eat too many carbs or eat foods high in carbs & fats simultaneously we effectively switch out body’s over to fat storage mode. Excessive carb intake which is beyond what our body can turn into fuel can get enzymatically converted to fatty acids in the liver and stored away in fat cells. This process happens because elevated blood sugar is very hazardous to the body. This problem gets further compounded when one is insulin resistant meaning it takes even more insulin secretion to get the job done, and like elevated blood sugar, elevated insulin is a signal to shut down fat metabolism.

If you think about it from a storage perspective, the average human can store somewhere around 50 grams of glycogen in the liver and 400-700 in the muscles and once these storage sites are full the only other opportunity is to take that excess glucose and store it in a different site that has theoretically unlimited capacity, fat cells. Under the right conditions insulin can be an aid in building muscle, recovery, and management of stress hormones. However, when it comes to fat loss, any time insulin is excessively elevated and activity is not upregulated to clear that blood sugar/burn stored energy, we are going to store.

Glucagon

Glucagon is the yang to inulin’s yin, meaning it comes out to play to regulate energy balance when insulin drops, and ONLY when it drops. Glucagon is responsible for the “catabolic” actions in regards to energy metabolism and gets released when blood sugar levels fall and energy requirements remain constant or increase. Generally speaking, when fasting blood sugar levels are low and sustained, glucagon will be released from the pancreas and initiate the breakdown of glycogen from the liver and free fatty acids from fat cells.

This is due to the fact that regardless of if we eat or not, we all have something called a basal metabolic rate which is determined by factors such as: age, gender, body composition, accustomed activity levels, etc. If we are trying to lose fat we want to find a way of being able to keep our caloric expenditure as high as possible from both a basal perspective AND an energy expenditure perspective while not elevating blood sugar excessively or constantly. This is why I can’t get behind eating 7 times a day to “burn” more calories because if we are making food choice which elevate our blood sugar, we are not getting the fat-burning benefits of glucagon release and MUST rely on scenarios like stress response and excessive activity to tap into fat loss.

In order for us to promote glucagon release we need to keep calories in a managed state (whatever that is for you), practice some form of carb restriction, and cycle activity to promote 2 variables; 1) the active lowering of blood sugar & 2) the enhancement of the ability to burn fat for energy, both while training (aerobic cardio) and to recovery from training (the aftermath of resistance or interval training). I will get into these exercise mechanisms later in the series because we can prime our physiology to become better fat burners by manipulating these 2 hormones as well as strategically selecting our activity to enhance the body’s mitochondrial function and fuel disposal.

To summarize the first part of hormones, we want to understand that insulin and glucagon play opposite role in this anabolic/catabolic balance of physiology. When it comes to fat loss, excessive insulin release can be problematic as it promotes fat storage AND biases the fuel selection towards carbohydrate metabolism, so it makes us better at fat storage and worse at fat burning. We will examine fat adaptation later on as another mechanism we can use to improve these pathways. Glucagon in contrast will promote the breakdown and release of fat from storage and enhance the body’s ability to burn it for energy given the opportunity to do so on a regular basis. With glucagon we just want to ensure that we aren’t dropping calories and protein too low as to not induce catabolic activity to muscle mass.