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The low-carb show 2/4

Many proponents of ketogenic diets strive to keep the body in a permanent state of ketosis. This is a very unnatural state for anybody to be in long term. Not even predatory animals that naturally subsist on a low carbohydrate diet, live in a permanent state of ketosis (6). They actually use gluconeogenesis to transform protein into glucose, and only when they suffer from prolonged starvation or when they are diabetic these animals will go into ketosis. This all makes sense because glucose is needed for intense bursts of energy, which most predatory animals need if they want to catch their prey.

The Inuit (Eskimo) people who live in the Arctic regions of Greenland, Canada, Alaska, and Siberia, are frequently cited by ketogenic diet advocates as a population adapted to a low carbohydrate diet. This is based on misinformation surrounding the dietary habits of the Inuit (7). It’s true that the Inuit traditionally subsisted on an almost all-meat diet, except for some 2 months in the summer when they could add some berries, grasses, tubers, seaweed and some other plant foods to their diet. A study from 1928 (8) on the traditional diet of the Inuit showed that they got most of their calories from fat and their diet was high in protein. They got some carbohydrates from eating raw meat which contains glycogen in the liver and muscle tissue. This, together with the gluconeogenesis from the high protein in their diet, provided them with enough carbohydrates to keep them out of ketosis.

A genetic mutation that occurred several thousands of years ago gave the Inuit a higher resistance to ketosis (9). In a state of fasting the Inuit will only develop a mild ketosis compared to other humans because of this mutation. This mutation is still found in 80% of the Inuit living in Greenland and Canada. A potential reason for this mutation is that ketosis is a dangerous metabolic state because it increases the acid levels in the blood and the diet of the Inuit already made them prone to acidosis. The calcium that the body uses to buffer this acid was also in low supply in their diet, as muscle tissue contains almost no calcium, their intake was well below the recommended intake (10). Mummified remains of two Inuit women that date back more than 2000 years showed that they suffered from osteoporosis, and that they had extensive hardening of the arteries. Reasons for this are the low calcium intake, the lack of sunshine and the high amount of protein in their diet with its acidifying effect.

The life expectancy of the Inuit is actually 10 years lower than for example the Danish population, and they have a much higher incidence of cerebrovascular events. Thus, the diet of the Inuit doesn’t show a population that’s well adapted to a low carbohydrate diet, it shows how well the human body can adapt to extreme circumstances. We can survive on a diet of raw and cooked meat, but we thrive on a plant-based diet.

The proposed benefits

So why do people go on a low carbohydrate or ketogenic diet? The most heard reason to go on a low carbohydrate diet is that it’s a miracle diet for weight loss. There are several mechanisms at work when you go on a low carbohydrate diet. When you start on a low carbohydrate diet you will initially lose lots of weight, but most of this weight is water. As you deprive your body from carbohydrates, you will deplete your bodies glycogen reserves which are stored in your liver and muscles. As the name carbo-hydrate already suggests, they are made out of carbon and water, and for each gram of glycogen that you burn, you will lose 3 to 4 grams of water. This could amount up to 4 kilograms of weight loss when you deplete your glycogen reserves.

When you deplete your glycogen reserves your body starts to use fat as an energy source. Fat is burned inefficiently when there are no carbohydrates present, and in the process several toxic by-products, ketones, are produced. One of these is acetone, the common ingredient in nail polish remover, which the body will get rid of through the lungs. Therefore, people on low carbohydrate diets often experience halitosis, or bad breath. The other toxic by-products are being expelled with the urine, for which the body uses lots of water to flush these toxic by-products out. This diuretic effect of a low carbohydrate diet can account for another 3 to 4 kilograms of weight loss, in the form of water.

If people on the diet keep losing weight after the initial weeks, it’s because they are eating less calories. A known side effect of a low carbohydrate or ketogenic diet is that it reduces your appetite. There is only so much fat that you can eat without getting nauseous. On a low carbohydrate diet, you will lose more weight in the short term, most of which is water weight, but in the long term there is no significant difference between low carbohydrate diets or a conventional weight loss diet.

Another benefit that is often advocated by low carbohydrate and ketogenic enthusiasts are beneficial changes in your lipid profile. These diets could potentially lower your triglycerides and raise your HDL cholesterol, which would potentially give you less chance for any type of cardiovascular event. The studies on the effect these diets have on your LDL Cholesterol are inconclusive, for some people on the diet it goes down, for others it goes up.

So, what do all these fancy terms tell us about the fat in our blood. The fat in our blood comes from two sources, the fats we eat, and the fat stored in our bodies cells. Most of the fat we eat consists of triglycerides and cholesterol. Cholesterol is not made by plants and we thus only find it in food from animal sources. Triglycerides are three fatty acids attached on a backbone of glycerol. These triglycerides get broken down during digestion into the individual fatty acids which are small enough to be absorbed in the small intestine. Once absorbed new triglycerides are formed which get packed together with cholesterol into a lipoprotein to make them ready for transport through the bloodstream.

These lipoproteins deliver the triglycerides to the cells of our body, where they are once again broken down into the individual fatty acids to be used as an energy source for our bodies cells or are stored as triglycerides for later use. When the fatty acids are delivered, what’s left is mostly cholesterol.

Cholesterol is an essential part of our body; the outer layer of the body’s cells is composed of cholesterol and cholesterol is also needed to make several hormones. Our body makes all the cholesterol we need, thus when we eat cholesterol containing foods (animal origin) this creates an excess. Cholesterol in food comes together with dietary fats, and this dietary fat makes the body produce even more cholesterol.

Cholesterol is divided into two main types, HDL (high density lipoprotein) & LDL (low density lipoprotein). HDL cholesterol is often called the good cholesterol because it goes towards the liver from where it is excreted into the intestines. LDL cholesterol transports the cholesterol towards our peripheral tissues and can lead to the build-up of cholesterol in your arteries to form plaques.

The fat that gets stored in our cells for later use are also a source of fat in the blood. If you do not eat for several hours the fat cells start releasing triglycerides into the bloodstream to be used as energy. The fat cells our body has stays constant with adulthood. Thus, what happens when we gain weight is that more fat gets stored in each fat cell, which stretches the fat cells up. This works up to a certain point, till the fat cells become so full that they start to release fatty acids back into the bloodstream, the so-called spill over effect. We see that obese people have higher concentrations of free fatty acids flowing through their bloodstream, but a slim person who eats a low carbohydrate diet can reach the same level of free fatty acids in their blood as an obese person has. This free fat that’s not packed in triglycerides in the bloodstream causes inflammation, oxidative stress and leads to insulin resistance, which in turn causes diabetes type2.

It all depends on what your diet was before you embark on a low carbohydrate diet if your triglycerides will come down. Triglycerides are used by the body to store any calories that are not directly needed, and if you overeat regularly your triglyceride level will rise. The best way to lower your triglycerides are healthy lifestyle choices, which includes eating less calories and avoiding sugar and refined carbohydrates, exercise, limiting your alcohol consumption and not smoking. So, if you’ve been eating lots of sugar and refined carbohydrates and have a sedentary lifestyle, your triglycerides will come down if you adopt a low carbohydrate diet.

HDL cholesterol levels can go up on a low carbohydrate diet as there is much more fat in the bloodstream to be cleared. Low levels of HDL cholesterol are not worrisome as long as the total cholesterol level is not to high either, there’s less need for HDL cholesterol to clear the bad LDL cholesterol out of the bloodstream. Very high levels of HDL cholesterol could actually be harmful. Total cholesterol levels can come down as well on a low carbohydrate diet, but weight loss by any means will lower your total cholesterol level.

The ability to cure diabetes type 2 is another purported effect of the low carbohydrate diet. Type 2 diabetes is a disease of insulin resistance which means that the pancreas is still producing insulin, but the cells become resistant to it. Normally insulin works as the key that opens up the body’s cells and lets the glucose in the bloodstream to enter the cells. When the cells become resistant to insulin the blood sugar level will rise which can lead to lots of health issues. The reason for the body’s cells to become resistant to insulin are intramyocellular lipids, fat particles that get stuck inside the body’s cells and impair the proper functioning of the cells. What you achieve with a low carbohydrate diet is to bring the blood sugar level down by consuming hardly any carbohydrates (sugars). This will help to control the blood sugar level but does not treat the cause of type 2 diabetes, the insulin resistance. Not a low carbohydrate diet but a low-fat diet will give the body the ability to process these fat particles that are stuck in the body’s cells and make the cells once again responsive to insulin (11).

Any diet that induces weight loss will be beneficial for your blood lipids and for managing diabetes. It all depends on what you have been eating before you start the diet, if you’ve been eating lots of white flour and sugar then you will certainly improve on a low carbohydrate diet, but on the long term this type of diet can have lots of undesirable side effects (12).

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