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  • Jesper Kjoller

Nutrition hacks

– How your diet can promote health and safer diving

By Jesper Kjøller

We all know that food plays a large role in our general well-being and health. But what if I told you that you can adapt nutritional strategies that will improve your dive safety by increasing your situational awareness and reduce the risk of oxygen seizures? According to new studies a high fat/low carb-diet not only supports longevity, facilitates weight loss and fights inflammation, but also appears to have interesting properties specifically related to diving.

Diabesity.[1] This is a new word we all have to learn. It is believed that more than a third of the American population is either pre-diabetic or are already suffering from clinical Type 2 diabetes[2], a condition that is almost always accompanied by obesity. Scientists are debating the causality – is obesity triggering diabetes or vice versa? Since it really doesn’t matter, the umbrella term diabesity has been suggested to describe the epidemy.

But why do more and more people suffer from diabesity – not only in America, but all over the world?

If you like med grew up with nutritional advise expressed in the food pyramids published by the health authority, you were told to base your nutrition on refined carbohydrates such as bread, rice, pasta and cereals, and to choose low fat versions of protein sources like meat and dairy. You were also encouraged to limit your intake of eggs and saturated fats because of the dangerous cholesterol. In my native Denmark, the nutritional recommendations came directly from government bodies under the Ministry of Health and were taught in the schools so obviously nobody questioned them.

Conspiracy theorists speculate that food industry conglomerates and powerful agricultural lobbyists has been behind the governmental nutrition campaigns in the western world, and we now know that there is no science to back them up. However, the messages were delivered with such a strong conviction that many still believe in the dogmas: fat makes you fat, breakfast is the most important meal of the day and diet soda, fruit juice and low-fat dairy are healthy options. These erroneous nutritional doctrines and the availability of cheap fast food, hyper-palatable carbs and heavily processed tv-dinners has triggered the world-wide diabesityepidemic.


Unless you won in the metabolic lottery and are able to consume almost anything without gaining weight, it is really easy to become obese when following the standard western nutrition guidelines. We all know the solution: diet. The question is: which diet? If we define the word diet as a period of increased focus on caloric restriction and maybe increased exercise, most diets tend to do a pretty decent job – in the short term. But most diets fail in the long run. Not only do they fail, but research has shown that most dieters tend to gain more weight after the diet, and that it is increasingly difficult to lose weight on the next diet.[3] Sounds familiar?

In other words: All diets work, hooray! But no diets work, bummer!

The majority of diets are based on the same strategy: create a caloric deficit by eating less and exercising more. How hard can it be, right? But there must be something fundamentally wrong with this approach since it has failed so miserably for so many years.

The low carb revolution

In the early 1970s Dr. Robert Atkins suggested a diet of fat and protein and very few carbohydrates. Many followers of the Atkins Diet lost weight on beef, bacon and butter, even if these food sources are very calorie dense. By purging carbs from the diet, the insulin is kept under control. Too much insulin can lead to insulin resistance, the main driver in diabesity.

The Paleo Diet, another low-carb diet, gained popularity in the late 2000s and took inspiration from a paleolithic nutrition regime consisting of only food items what was available to our hunter/gather ancestors before the invention of agriculture introduced grains as a major source of calories. Humans only farmed the land for about 10.000 years, a minor fraction of our existence on the planet and utterly insignificant in an evolutionary and biochemical perspective.

We are not designed to consume and process loads of refined carbohydrates because we only got access to them yesterday. We are not designed to ingest processed food, because we did not have the technology to process food until yesterday. We are designed to eat protein and fat from animals and maybe more fat from coconuts, avocados and olives. And perhaps a little bit of sugar from honey and ripe fruits and berries when they were in season. We are also designed to sustain shorter or longer periods of fasting when our hunting luck failed us.

I’m sorry if I offend the vegetarian community, but though I can sympathize with the ethical rationale for a vegan lifestyle, a purely plant-based diet can’t be justified in an evolutionary and genetic perspective. From a biological standpoint, humans are primarily carnivores, even if there are geographical and racial variations.

Even if they are different diets in some aspects, both Atkins and Paleo will stimulate the body’s ability to run on fuel made from fats (so called ketone-bodies) instead of fuel made from glucose (carbohydrates and sugar). The human body can’t function without an external supply of essential macronutrients (fat and protein), but we do not need to consume any carbohydrates at all. They are not essential. Very few systems in the body can only run on glucose, and the body can synthesize glucose when needed. Fat based fuel in the form of ketones is believed to be a much better and cleaner energy source for our organs, muscles and brain. [4]

Keto – low carb 2.0

Even if the original ketogenic diet is older than both Atkins and Paleo, it has recently found a large following. Historically the keto strategy was developed to treat epilepsy in the 1920s and 1930s, but after the development of new anticonvulsant drugs, it was largely abandoned. However, 20-30% fail to achieve seizure control on the drugs. For this group, and for children in particular, a therapeutic ketogenic diet found a new role in epilepsy management. [5]

By forcing your body to run on ketones instead of carbs, you basically teach it to feed on itself. At any given time, an average adult has less than a teaspoon of sugar in the bloodstream, but easily 30-40.000 calories stored as fat.

Let’s say you have a living room heated by a fireplace. If you light a few newspapers, they will burn easily but quickly. However, if you can go outside to the woodshed and haul in some logs, they will keep burning for hours and hours. Being in ketosis is equivalent to getting rid of newspapers as a fuel source and moving all the logs close to the fireplace so they are ready to throw in.

Your body is smart. It is not going to start to feed on your muscle mass. That would be equivalent to burning expensive furniture when you have an ample supply of chopped firewood.

So how do you do it? There are three ways of achieving the coveted ketosis nirvana. 1) fasting, 2) nutritional ketosis and 3) therapeutic ketosis.

Since ketosis requires a serious restriction of your carb intake, fasting is a very efficient way to get there fast (pun intended). Instead of eating low carbs or no carbs, it is easier not eating at all. In fact, many people are in a mild state of ketosis every morning after 10-12 hours of not eating. Intermittent fasting protocols such as 16:8, OMAD (one meal a day), the warrior diet and other fasting modalities has proven very efficient and popular – not only for getting in ketosis, but also as a very efficient treatment for Type 2 diabetes.

Nutritional ketosis is the process of manipulating the macronutrient ratio to roughly 75% fat, 20% protein and 5% carbs. The precise ratio is often debated and probably very individual. The most difficult part is getting the carbs really low, as many vegetables also contains carbs. An extreme version is the carnivore régime that completely cuts away all plant-based food sources. I hear the vegan community cringe, but let’s save that discussion for another time. By the way, it is entirely possible to combine a vegan and ketogenic lifestyle, all though it requires a lot of supplements to work.

Therapeutic ketosis is the process of obtaining or reinforcing a state of ketosis by ingesting external ketone supplements. To be efficient it must be combined with fasting and/or nutritional ketosis.

It takes from a few days to a few weeks to get in ketosis, but most will need additional 60-90 days to get completely fat-adapted. You can purchase inexpensive instruments to measure ketones in your urine, breath or blood, so you can precisely monitor the cause/effect relations of your food and exercise. You have to experiment a little, but it is part of the fun.

A ketonic eating paradigm is considered to have a long list of benefits and the weight loss may in the long run be the least interesting. A fat-adapted body that primarily runs on ketones is believed to benefit longevity, reduce inflammation, autoimmune syndrome and decrease the risk of cancer and Alzheimer’s. I know, these are rather big claims, but do a little research on your own and you will find that there is a solid body of scientific research to back it up.

Diving and ketosis

Divers have many reasons to be healthy. GUE takes this a step further as the only diving organization that dares to quantify a minimum required baseline for health and fitness on different certification levels. That means a fairly low BMI, good cardiovascular health and no smoking. As divers we want to be relatively immune to temperature stress and we want to have a reasonable amount of muscle and joint flexibility to be able to carry heavy gear and have good posture while diving. We also need a lean body and efficient circulation to promote successful elimination of inert gases and to provide an extra energy reserve in emergency situations.

And we want to maintain our vigor for as long as possible, so we do not have to eBay all our dive gear in our mid-forties for health reasons. I am 55 and I plan to keep diving for many years.

These health parameters are expressed in the fitness test that all GUE instructors have to complete yearly to stay in teaching status and also in the swim and breath-hold test that is a part of all GUE courses.

A diet without processed food and refined carbohydrates (such as Atkins, Paleo or LCHF), or a more targeted keto-protocol with a specific controlled macro-ratio will greatly benefit your diving because it promotes all the above health parameters.

The improved mental clarity that many experiences while on ketosis will also give you an edge on a dive. It will increase your situational awareness – it could be described as having much more helium in the cylinder…

But emerging evidence published in the American Journal of Physiology suggests that ketosis also can prevent CNS oxygen toxicity. Ketones are neuroprotective and the molecules help to preserve brain energy metabolism under periods of high oxidative stress associated with diving and hyperbaric oxygen therapy. This research is sponsored by US Navy and spearheaded by Dr. Dominic D’Agostino and his team. [6]

The conclusion is that not only will be being in a state of ketosis (induced by nutrition, periodic fasting and/or supplemental ketones) benefit your mental state during the dive, if will also protect you from seizures while doing decompression with elevated pO2 values or if you have to undergo recompression therapy after the dive.

It is not surprising that the benefits of being in ketosis such as improved mental clarity and ability to run on the body’s internal fuel for many days has sparked interest in the military community, and it is very likely that right now several special forces are operating behind enemy lines while being in ketosis.

In short

If you are struggling with the waistline, it is worth considering this: Improved health is not a result of weight loss. Weight loss is a result of improved health. A food paradigm that will reduce inflammation, increase your mental functions and control metabolic hormones will eventually also reduce your waistline in a sustainable manner.

Don’t take my word for it. Do your own research. Between YouTube, the blogosphere and the podcasts universe you will find information to last you a lifetime. But to make it easier for you, I have listed a few of the – in my opinion – most creditable keto-warriors. I personally tend to lean towards people that 1) base their advice on solid research, 2) walk the talk and 3) has clinical experience with real patients.

This list will help you steer away from the worst bro-science.

Google keto + Dom D’Agostino, Ted Naiman, Ben Bikman or Peter Attia.

[1] [2] [3] [4] [5] [6]

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