Ketogenic Diets, Low Carb Diets and Metabolic Adaptation

This post is neither for or against Ketogenic and low carb diets.  However, it is intended to share my personal experience with ketogenic diets, clarify the term diet, provide clarity on the value of of going into ketosis and most importantly bring to light the unintended consequences of long term, low carb diets.

As an athlete and nutrition coach, I have personally tried a gamete of nutritional tactics in an attempt to manipulate my physiology; one of which was a low carb ketogenic diet. At the time when I first found keto I was no longer an athlete, working in a high stress office job where I received little sleep, sat all day long, did not exercise consistently and ate horribly.  My physique had quickly gotten away from me and I needed to make a change. Long story short keto worked well and I lost a lot of “weight”; however I also lost an immense about of lean mass, end up lean but not very muscular and declined in about every way in the gym other than pull ups and cardio.  Although the scale went down I was still not very happy with the way my physique looked, but I kept eating keto for a year.  But an interesting phenomena began to happen, my body began to fight back;  I started to gain body fat, my cravings for sugars were insanely high and I just didn’t feel healthy.  I also felt tired all the time and I could not make any strength gains in the gym. In the end, I took a break from it all and ended up right back where I started before keto.  

Fast forward another year and I was in need of change again; however this time the goal was sustainability. When I was an athlete I rarely chastised certain food groups and as a result I was big, strong and relatively fast.  What was different about what I was doing then and what I was doing with Ketogenic? The answer was, carbohydrates. So I turned to macro based diet and structured a high carb, moderate, fat high protein diet. The results were phenomenal,

In the paragraphs below I intend to share with you the knowledge and research that I have gain over the years as it relates to health and I hope to share with you my experience, observation, research, how I now use keto and where I believe ketogenic diets go wrong. I care much less about the efficacy of low carbs diet, as much as I care about the secondary effects of low carb states, the unintended consequence and how to manage these risks in order to maintain results both physiologically and psychologically

The effects of ketogenic on body composition:

Ketogenic diets are a tool, but not a permanent way of eating. In Fact Dr. Jack Kurse suggests that ketogenic diets are a natural part of humans physiology due to the cyclic nature of the types a foods available during certain seasons.  Therefore you could make the anthropological argument, similar to that of the PALEO community, that ketosis is natural; and that the agricultural revolution has allowed us to eat foods during certain times of the year, that would otherwise not naturally occur.  That being said I am not sure that we could ever prove this concept without the ability to travel through time.  I will say this however, you only see obesity in domesticated pets but never in the wild :).

We can, however, glean some ideas as to what is possible via our understanding of nutrition and human physiology.  

Let’s look at what we know to be true:

Just about every receptor in your body use glucose. But the body create glucose from non-carbohydrate sources in a process called gluconeogenesis. But is this really all that efficient? Maybe that is the point? Lowering one’s carbohydrate intake is an effective strategy to decrease caloric load and create a deficit necessary to lose fat.  The question however is this more effective than a low fat diet and which is better for lean tissue preservation?  There are arguments for both camps and I believe that this is the point.  Both ketogenic diets and carb rich diets a valid. From experience and from research we find that ketogenic and low carb diets are both muscle sparing and can increase satiety. We also know that the body can create glucose via gluconeogenesis in the absence of carbohydrates  However, there are a couple of important secondary and tertiary impacts that are often overlooked in the absence of insulin; as a result they lead to a rise in hunger hormones which lowers satiety and down-regulates the Thyroid hormones T3 and T4. We can also consider that theh the body does not need insulin to uptake glucose, because there is one of the GLUT transporters that needs insulin – GLUT 4.  But beyond glucose uptake, insulin is required to maintain other process in our body.

Secondly, I believe that is so much debate in nutrition about this topic because we are not using the same definition of the word diet.  Nutritional scientist view diet as the food that you eat, the misguided general population use diet as a way to lose weight, change the way you look, get skinny and eat a little amount of food. However we have to understand the clear difference between the macronutrient composition of your diet and using ketosis as a tool to diet (i.e. lose body fat/weight via creating a caloric deficit.)  This distinction is crucial to understanding the importance of ketogenic diets as a tool.  Lowering carbohydrates to create a caloric deficit and potentially moving someone into ketogenesis is an excellent way to improve insulin sensitivity, limit carbohydrate options, change eating habits and shed body fat.  However, the unintended consequences can lead to far greater physiological problems; and psychological problems due to cravings and food guilt.  Both of these issue are observed in individuals who prep for bodybuilding contests. When the contest is over the bodybuilders have a tendency to overeat, which in turn leads to rapid fat gain (10lbs of pure fat in 24 hours is not uncommon), an insatiable hunger and a psychological battle between eating balanced and binging on high carb foods.

The unintended consequences of low carbohydrate diets:

Thyroid hormone down regulation in the absence of insulin: Plain and simple your thyroid relies on insulin to keep it stimulated and continually produce its hormones T3 and T4.  I cannot tell you the number of clients whom I have worked with you eat a low carb diet, can’t lose a pound have some form of hypothyroidism, clinically diagnosed or not.  Also in an observation study of every paleo eater that I know they all experience the same effect : a massive body fat rebound.

Hunger Hormones – leptin and increased satiety. There is a congruent relationship between leptin and insulin. When fat mass increases, so do leptin levels and one’s appetite is suppressed until weight loss occurs. In this way leptin regulates energy intake and fat stores so that weight is maintained within a relatively narrow range. In this way insulin sensitivity and leptin regulation are inversely related. Cell signaling occurs in adipocytes.  

Therefore in the case of excess body fat your leptin levels tend to rise, due both to adipose tissue and insulin signaling.  This is why over-fat and obese people tend to have poor insulin sensitivity.   So in this way, a lower carb diet offers opportunity to create the caloric deficit necessary to shed body fat and lower insulin sensitivity.  However, there is a tipping point when body fat levels have reached an acceptable level, insulin sensitivity has normalized at which carbohydrates must be reintroduced.  Otherwise you run the risk of a serious rise in Leptin and an insatiable hunger.  Research on this is ever evolving but low carb diets when coupled with calorie restrictions have shown to increase your hunger hormones for up to a year. The psychological side of nutrition and using food as a coping mechanism is just as important as the physiological.

Metabolic Adaptation due to caloric deficit and down regulation of T3 and T4 –  The reason that keto works for most people is it immediately puts them in a caloric deficit, increases the Thermic effect of food and results in weight loss.   But I have yet to find an elite level athlete, bodybuilder or  general pop. who has a lean and absolutely shredded physique on a true ketogenic diet without some sort of ‘carb back loading’ or ‘cyclic’ method to spike insulin via carbohydrates periodically and to replenish glycogen.  The closest thing to a performance bump that we see is found in aerobic athletes – i.e. elite marathon runners. But how many elite marathoners have a great and healthy physique.  It’s not uncommon for elite marathoners to to have a vertical jump of 2 inches.  Yes 2 inches!!!….but I digress.  Therefore, there is time component associated with how long one can stay in a both a calorie deficit and/or a ketogenic state.  In the absence of insulin your body will down regulate the production of thyroid Hormones. This concept is something that bodybuilders have understood for years, which is why in a low carb state  for more than an acceptable amount of time they will supplement T3 endogenously in order to prevent their metabolism from down regulating.

In conclusion, there are arguments for both sides, but as nutritionist we must not take a side and better understand what we are doing and the impacts of both.  Macronutrients are simply tools and with better understanding of the pros and cons we can manipulate them to deliver unmatched physiological results.  Food is medicine.  The neutral ground for boths side could live in Glycemic index based diets, which offer a way to control insulin, deliver an insulin response, and increase the thermogenic effect of food, while still delivering the body with its primary macronutrient sources carbohydrates.


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