Originally published on HVMN by Nate Martins
“If I eat so much fat, won’t I get heart disease?”
The shortest answer is NO. There are different types of dietary fats and keto diet is focusing on saturated and unsaturated fats which gives you energy and compensate for reduction of energy that comes from carbs.
These are commonly found in animal products and oils (coconut oil, palm oil, palm kernel oil, olive oil). For years, saturated fat was believed to be a key cause of heart disease. The opinion was primarily based on the result of public health studies which had many methodological flaws and biases which were neglected during the studies.
A recent, more comprehensive study found that people who ate more saturated fat had an overall lower mortality rate and no increase in death from heart disease. So, incorporating saturated fat while following a ketogenic diet doesn’t appear to be the health risk it was pegged.
Avocados are the poster child of “good fats.” This type of fat, often found in plant-based foods, can be separated into polyunsaturated fats (found in fish and walnuts) and monounsaturated fats (found in avocados, flaxseed oils, nuts and seeds). There’s evidence that replacing saturated fats with “good” unsaturated fats can lower the risk of heart disease and help prevent insulin resistance.
A recent study illustrated that switching from a carb rich diet to a diet higher in unsaturated fats reduced cardiovascular risk, lowered blood pressure, and improved cholesterol and lipid levels.
These are harmful fats, found mostly in vegetable oils when they’re partially hydrogenated through heating. They’re also found in processed snacks, baked goods and margarine–foods to avoid while on ketogenic diet.
Regarding the keto diet, experts recommend focusing not on total cholesterol levels of the food, but instead on the impact food has on LDL and HDL ratios. Consuming plenty of polyunsaturated fats increases blood HDL levels while reducing LDL. Since saturated fats and trans fats increase LDL levels, these should be reduced.
Still, it’s important to keep track of blood biomarkers when starting out on a ketogenic diet to help ensure the diet isn’t increasing risk factors for heart disease.
Produced by the liver, cholesterol is also derived from our diet. People often assume that eating foods rich in cholesterol will raise cholesterol levels and increase the likelihood of a heart attack. But it’s more complicated than that. Cholesterol-rich foods feature heavily in the keto diet (butter, eggs, red meat); but there are two types of cholesterol. “Bad” LDL cholesterol (think L = lethal) is linked to clogging of the arteries. “Good” HDL cholesterol (think H = healthy) clears cholesterol from the blood.
Research shows there is a weak relationship between levels of dietary cholesterol and blood cholesterol. The effect isn’t the same for everyone either. There are “responders” and “non-responders” to dietary cholesterol; some people experience higher fluctuations in blood cholesterol levels according to the amount of cholesterol they eat, while others are more stable.
“You’ll get fat eating all that fat!”
Often the biggest misconception about the keto diet: eating fat leads to weight gain or obesity.
That’s likely because we’ve been conditioned to believe eating a low-fat diet leads to weight loss. But all dietary fat doesn’t end up as belly fat.
When we eat proteins and carbohydrates, the pancreas releases insulin into the blood. Insulin is a hormone that signals to our cells to absorb nutrients (such as glucose) and to start using glucose for energy. Any excess glucose is stored as glycogen or converted into fat by the liver or specialized fat storage cells.
Insulin isn’t released when fat is consumed. Fat is absorbed in the intestines and enters the bloodstream circulation as lipoproteins. Fat is a major source of energy for the body, so much of the fat consumed in food is used to keep us alive.
Excess fat is broken down and stored as fatty acids in the liver, or as body fat. This shows that even though proteins, fats, and carbohydrates may be metabolized differently, in both mechanisms the excess food energy is stored as body fat.
Dietary Fat Doesn’t Immediately End Up as Body Fat
Instead, it should be recognized that in excess food in general–whether carbohydrates, proteins or fat–can become body fat.
Low-calorie, low-carbohydrate diets are increasingly recognized to be more satiating than low-calorie mixed diets (meaning, overall calorie intake is reduced to promote weight loss). Many people on the keto diet commonly experience the feeling of being more satisfied after eating, and this could contribute to weight loss–but scientists have yet to find a clear advantage of keto for weight loss when compared to any other calorie-controlled diet.
“Keto diets aren’t ‘complete’ and lead to nutrient deficiency.”
Balance is important in any diet, and a proper keto diet should incorporate nutrient-rich foods.
Losing essential micronutrients is another concern raised by keto diet sceptics. People say eating a diet based on fat and protein from animal sources means losing those micronutrients found in higher-carb grains, legumes, fruits, and vegetables. Some also claim low-carb diets contain too little fiber and thus may cause long-term constipation. That’s inaccurate.
Nutrient-Rich and Keto-Approved
There are many options for nutrient-rich, low-carb foods, and they should be frequently incorporated into the keto diet.
Examples include non-starchy fruits and vegetables such as leafy greens, mushrooms, bell peppers, and berries. The trace minerals and vitamins found in grains can also be obtained at higher percentages in good-quality meats and dairy products. Moreover, compounds such as phytates and tannins in grains hinder the bioavailability of several minerals.
A properly constructed keto diet may even be higher in nutrients than a standard American diet, especially when things like candy, refined flour, soda, and processed carbs are eradicated.
A well-formulated keto diet should feature plenty of whole, unprocessed foods and shouldn’t lead to nutritional deficiencies.
“Doesn’t the keto diet cause dangerous ketoacidosis?”
These are two very different terms, but ketosis and ketoacidosis are often confused. The keto diet doesn’t cause ketoacidosis.
Ketosis indicates the presence of ketones in the blood at > 0.5 mM. Achieving ketosis can happen through diet or fasting.
When people reach ketosis through fasting, ketone levels naturally plateaued at ~8 mM after 41 days of starvation. This is far lower than ketone levels during ketoacidosis. A ketogenic diet should only result in ketone levels that fall within a natural and safe range.
This is a condition typically seen in Type-1 diabetics, where ketones and blood sugar levels are both dangerously high (ketone levels at 20+ mM). The key factor in the development of ketoacidosis is a lack of insulin. The cells cannot shuttle in glucose from the bloodstream for energy use and the body has no signal to stop releasing fats (which are converted into ketones). Those who have even a small amount of insulin secretion do not often reach this metabolic state.
When ketone levels get too high, the blood becomes too acidic, which could potentially become life-threatening. Other medical problems linked to ketoacidosis include alcoholism, overactive thyroid, and infections such as pneumonia or drug abuse.
Ketoacidosis isn’t a danger directly associated with the ketogenic diet.
“Could the keto diet cause hormonal imbalance?”
Hormonal response between individuals on the keto diet varies widely (including between men and women). A careful keto dieter should be able to maintain a healthy hormonal balance.
Hormonal imbalance is a hot-button topic when it comes to the keto diet. There’s a discrepancy in the scientific results, which may stem from differences in the exact dietary protocols used, and the cohorts studied.
This is one of the first hormones most people think will suffer via the ketogenic diet. Cortisol is called the “stress hormone” in the body due to its role in stress response, and several other functions like breaking down fat and protein to make glucose. It also controls sleep and wakefulness as well as regulation of blood pressure.
Chronically high cortisol levels are detrimental to health and may increase the risk of heart disease. Are these levels possible to attain while on the keto diet? Only if you aren’t careful.
A lack of sodium on the ketogenic diet can cause the brain to send signals to the adrenal gland to increase the release of hormones responsible for water balance. Cortisol is released alongside these other hormones.
If sodium consumption is enough to maintain a normal water balance, then cortisol levels should stay stable. Few studies have measured cortisol levels of people on keto and the results are inconclusive. One study found that cortisol increased over time in subjects given a ketogenic diet with a low/inadequate sodium intake.
Another study showed no change in cortisol after six weeks of a well-formulated ketogenic diet. Cortisol is infrequently measured, which may be an indication that generally, doctors and scientists have few concerns about cortisol on a ketogenic diet.
A supposed danger of the keto diet is a negative impact on thyroid function.
The thyroid hormones have several functions, including control of the body’s metabolic rate, digestion, and muscle control, among others. The ketogenic diet is linked with a decline in the amount of active thyroid (T3) in the body, which is why it’s assumed the diet impairs thyroid functioning.
However, this is not backed by any solid studies. The body’s sensitivity to T3 has been hypothesized to increase as a result of the ketogenic diet, in a similar way increased sensitivity to other hormones occurs during the diet. As the body becomes more responsive T3, it may function just as well or even better than before with lower T3.
Studies point to the beneficial effects of lowered T3 to assist in sparing lean muscle. Lowered T3 is even hypothesized to be an adaptive mechanism increasing longevity.
Regarding metabolism: one study found when men on either the ketogenic diet or the low-fat diet were compared, their resting metabolic rates were not different despite lowered T3 on the ketogenic diet. Of the several studies done on the ketogenic diet, none have reported significant cases of hypothyroidism–essentially, the thyroid can function fine while following a ketogenic diet.
“I’ve heard that the keto diet causes kidney stones and gallstones.”
The unfounded association between the ketogenic diet and kidney stones is perhaps due to the supposed link between dietary protein and kidney stones–there’s a common confusion between the ketogenic diet and a high-protein diet.
Can Keto Cause Kidney Stones?
Kidney stones are mineral deposits in the kidneys. They can be caused by multiple things–including dehydration, high sodium intake, family history, and excessively high consumption of protein (> 200g per day). A true ketogenic diet is low-carb, moderate-protein, and high-fat. There’s no solid evidence that protein consumption at levels seen in a typical ketogenic diet could cause kidney stones.
Another common false connection exists between the keto diet and increased risk of gallbladder issues.
The main role of the gallbladder is to store bile (which is made in the liver), and in turn, the role of bile is to digest fat. People assume that eating a lot of fat is somehow linked to an increased risk of gallstones, which are solid deposits of cholesterol and bile that can form in the gallbladder. But most of the cholesterol in the bloodstream is made inside the body (as part of a tightly regulated process inside the liver), not derived from the diet.
None of the common causes of gallstones (including inherited body chemistry, body weight, low gallbladder motility, and low-calorie diet) is linked to the keto diet.
Comparing those who lose weight on a low-fat diet versus a low-carb diet, studies show those on the low-fat diet are more at risk of developing gallstones. And eating high fat is thought to stimulate gallbladder emptying, which could be even protective against stone formation.