Promoted as an ideal strategy for weight-loss, energy and longevity, ketosis (burning fat for fuel) is the latest dietary trend. You would think that the trendiness of ketosis alone would serve as a warning flag; however, people continue to hop on the ketosis bandwagon.
The aim of this post is to provide the basic science about ketosis so rather than being sold on the idea of ketosis, you can make informed decisions. So without further-ado, let’s get into the science of ketosis.
HOW KETOSIS WORKS
Ketosis is a secondary form of lipolysis – you can’t be in ketosis without being in lipolysis. Lipolysis is the breakdown of fat in the body into its usable form. Fat oxidation is the burning of fat for energy.
While this sounds good from a glance, the fact of the matter is lipolysis is associated with the stress hormones, which mobilize fat stores when glucose/energy is low, but are associated with other deleterious effects as well. In other words, to enter ketosis, cortisol and stress hormone must be chronically elevated. And chronically elevated levels of cortisol can damage the adrenals and hypothalamus and suppress the thyroid. Cortisol is a catabolic stress hormone that can degenerate and damage tissues in the body, leading to wrinkles, joint problems and degenerative aging.
Looking to the Randal Cycle (also known as the glucose fatty-acid cycle); this is a metabolic process involving the competition of glucose and fatty acids for substrates. In general, fat oxidation is less desirable than carbohydrate oxidation, for a few simple reasons. One, fat oxidative is a metabolic stress that is initiated by stress hormone section. Two, during lipolysis less CO2 is produced, and CO2 has a variety of beneficial effects (and low CO2 some negative ones).
Since fat competes with carbohydrates via the randle cycle, elevated fat can have negative implications whether it is exogenous (from food), or doubly so when endogenous through lipolysis.
KETOSIS, STRESS METABOLISM & THE DAMAGING EFFECTS
So, what does it mean physiologically to be in ketosis? To get into ketosis, you dramatically cut down carbs and expend your liver glycogen (energy). As a result, your body will produce an increase of adaptive stress hormones, which will trigger lipolysis. This is what it means to be a “fat burner”.
Additionally, through this process of using fat for fuel, fatty acids and ammonia are liberated from the tissues and lactic acid is produced (rather than CO2). This poses a few problems; these are similar conditions of stress metabolism, which typically involves an excess of the adaptive hormones, lactic acid, and decreased CO2.
As the shift from glucose for energy to fat for energy occurs, the depletion of glucose increases the production of lactic acid, which causes cortisol to increase. Increased cortisol and free fatty acid levels activates the Randle effect, which inhibits glucose oxidation. This accelerates the breakdown of protein into amino acids, and activates the enzyme fatty acid synthase, which produces fatty acids from amino acids and pyruvate, to be oxidized in a “futile cycle,” producing heat, and therefore increases the liberation of ammonia from the amino acids. Ammonia and lactic acid are very aging in the body, they suppress respiration and are present in rosacea, arthritis, heart disease, diabetes, neurological diseases and cancer.
GLUCONEOGENESIS, CORTISOL AND THYROID
Something not many people realize is how important glucose is. Our bodies have an absolute need for glucose to support glycolysis, so much so, that it has a very well designed system for ensuring it always has enough glucose (even under conditions of dietary carbohydrate deprivation like ketosis).
This process is referred to as gluconeogenesis, which is the process of producing of glucose from non-carbohydrate precursors. Gluconeogenesis is primarily supported by protein but is also supported to a minor degree by fat.
In the case of ketosis (extremely low-carbohydrate intake), a person is coming close to suffering from a deficiency of total glucose. As a result, the body will naturally do everything in they can to conserve its glucose through this process.
This seems great, but again, is an adaptive stress response by the body in attempt to survive. To understand this, consider the fact that gluconeogenesis is primarily stimulated by the adrenal hormone cortisol. Through this process, cortisol antagonizes thyroid hormone and as result, metabolism down regulates, circulation and respiration become poor and the immune system becomes impaired.
so, as we move away from burning glucose and toward greater reliance on fat, free fatty acids elevate. Cortisol augments this rise even further by causing us to release free fatty acids from adipose tissue. Lactic acid, cortisol, and free fatty acids impair thyroid hormone’s ability to carry out its many physiological functions and consequently, a person can suffer from hypothyroid and the many symptoms, which include:
- chronic fatigue
- cold intolerance
- brittle nails
- constipation
- dry skin
- high cholesterol
- irritability
- sensitivity to cold
- infertility/sexual dysfunction
- slow heart rate,
- weight gain & trouble losing weight
IN CONCLUSION
To summarize, entering a state of ketosis is nothing smelling our ancestors did intentionally, if anything, they desperately attempted to avoid it. In the simplest of words, ketosis is a biological and metabolic stress that would ideally be avoided if one wishes to be healthy and have a balanced healthy weight.
If you’ve enjoyed this information and would like to learn more about the science of weight loss, be sure to check out my online course Healthy Weight Loss.