After the enormous success of the keto diet, many cardiologists and nutritionists have begun to reconsider the actual causes of heart disease, especially since the keto diet is based on a significant reduction in carbohydrates and reliance on fats as an alternative source.
These reviews then led to the introduction of the keto diet in treatments for diabetes and cancer, as it became clear to scientists that cancer cells feed on glucose from bread and starches in general, and that cutting bread is an available solution to stop the progression of the disease and even cure it.
The countless and countless diets come and go every day, but these days there is a system that we never stop hearing about, whether you call it a low-carb diet, the Atkins diet, keto, or paleo, the principle is the same: reduce starchy foods and satiety with fats and proteins .
Obesity and diabetes specialists are increasingly relying on low-carb diets, and an increasing number of experiments are showing that this approach helps people lose weight, at least like traditional low-fat and calorie diets, and more people eat this way not to lose weight but because they see it as more. Health.
Even so, many doctors caution against the dangers of eating low-carbohydrates, and point to large-scale population studies linking low-carb diets to an increased risk of heart attack, stroke and premature death.
The puzzling thing is that these warnings do not appear to coincide with clinical trial results, and are generally a better type of medical evidence than population studies.
Many have now shown that generally low-carb diets do not raise levels of "bad cholesterol," which has long been seen as a major risk factor for heart attack and stroke, and even in people who are high, other indicators of heart health usually improve.
It's so baffling, that some even question whether the causes of heart disease are wrong.
"It led me to question whether I believed in the cholesterol hypothesis at all," says Eric Westman, an obesity specialist at Duke University in North Carolina.
With rates of obesity and increasing diabetes threatening public health, questions about the safety of low-carb diets are becoming increasingly urgent.
So, is cutting carbs a safe way to lose weight and stay healthy, or is it a recipe for heart attacks?
Low-carb diets were first popularized in the 1970s by New York cardiologist Robert Atkins, who personally lost weight in this way and recommended them in diet and cooking books.
His advice to eat steak, cream and butter, while avoiding most fruits and vegetables, made him shun the treatment.
Critics said people wouldn't be able to hold on to it, and if they did it would kill them, says Westman who studied during the Atkins era.
New York Cardiologist Robert Atkins Before and After the Diet
For many people, low-carb diets clearly work.
By the early 1990s, randomized trials showed that such diets are as good, at least as low in fat, for weight loss, and often slightly better.
In one experiment, people who followed a low-carb diet lost an average of 4.4% of their body weight after a year, compared to 2.5% among those in the low-fat group.
Contrary to warnings, people's cholesterol levels and other blood test results generally move in the right direction, says Westman, who led some of those studies, "That was a great moment."
What is the explanation?
The central idea is that controlling weight requires more than just counting calories.
First of all, the same amount of calories from fat or protein makes people feel more full than if that amount came from carbohydrates, which explains why people who follow low-carb diets experience less hunger than those who follow a low-fat diet.
Westman's studies helped show that although most people who follow a low-carb diet do not count calories, they tend to consume only 1,200 to 1,500 calories per day, well below 2,000 calories per day for women and 2,500 for men.
"They are eating less because they are not hungry," says Westman.
The other major insight has to do with what happens when we change the body's main energy source.
We usually feed our cells with glucose, a simple sugar into which all forms of sugar or starch are converted.
Glucose is highly reactive, so our bodies usually keep the amount in the blood within a narrow range to avoid damage to blood vessels and cell structures.
When glucose levels rise after eating, we quickly release the hormone insulin that tells cells to start taking up, using and storing glucose.
Insulin has a host of other effects, but it can be summed up as a signal to our bodies that we are getting a caloric flow and we need to eliminate them.
Crucially, insulin causes fat cells to convert glucose into fat and store it.
But in the absence of glucose, the body has an alternative fuel source: fat.
Depending on the type of cell, the stored fats can be converted into fatty acids or into molecules called ketones, which can be used for energy.
This usually happens overnight when we have spent several hours without eating any carbohydrates.
The reason for having low carbohydrates is to reduce insulin secretion and provide it with ketones as much as possible.
For most people, the switch to what is known as "ketosis" occurs within a few days of cutting back on too many carbohydrates.
Eating very low levels of carbohydrates is also known as a ketogenic diet.
In addition to people trying to lose weight, many people have adopted a low-carb diet or keto diet because they see it as a way to live healthily and extend life.
Some adherents of ketosis believe that going into ketosis has a host of metabolic benefits, including stopping cancer and Alzheimer's disease although there is no good evidence for this.
Neurologists use low-carb diets to induce ketosis as a treatment for certain forms of epilepsy, and are being investigated in others as well.
What has granted lower-carb intake more legitimacy recently is its effect on type 2 diabetes.
This condition occurs when the body's cells become less sensitive to insulin, a condition known as insulin resistance, which leads to a dangerous spike in blood sugar after meals.
In the long term, these increases in sugar contribute to many of the health consequences of diabetes, including nerve damage, and kidney and heart disease.
The medical doctrine says that because diabetes increases the risk of heart disease, it is very important that sufferers avoid saturated fats, which are found mainly in red meat and dairy products, as they are believed to raise blood cholesterol and lead to clogged arteries.
The National Health Service advice in type 2 diabetes is that people should reduce fats to a minimum and eat starchy foods like pasta, for example.
But this ignores the fact that people with diabetes may find two benefits in lower carbs.
In addition to losing weight, which improves their insulin sensitivity, avoiding starch and sugar reduces hyperglycemia.
Remember that starch is long chains of sugar molecules.
People with diabetes often measure their blood sugar at home and can see for themselves that starting the day with meat and eggs increases blood sugar by less than toast or cereal.
Skeptics would argue that while a few days of low-carb intake lower blood sugar levels, it's hard to stick to this way of eating.
There is mixed evidence on this issue.
For example, a review of ten randomized trials found that low-carb diets were more effective than low-fat diets in improving blood sugar control in people with diabetes during the first year, but the differences subsequently disappeared.
But there is evidence that for those who maintain it, the health benefits could persist in the long term, such as a study of 128 people with type 2 diabetes who went to low-carb counseling sessions led by David Unwin, a family physician in Southport at United kingdom.
After a follow-up of an average of two years, nearly half were able to stop all diabetes medications.
Many have begun to question whether “bad cholesterol” really poses a risk to heart health because of findings like these, and diabetes doctors and patient support groups have begun to question the low-fat nodule as well.
Bodies like Diabetes UK and Diabetes Australia now say that eating low carbohydrates is a viable option for losing weight.
Ten years ago, we couldn't hear that.
Then the American Diabetes Association took another step forward last year and said that of all dietary strategies, low carbohydrates have the most supportive evidence for improving blood sugar control.
However, as more people adopt this method of eating, questions have been raised about its safety.
In some cases, low-carb diets can lead to an alarming change in people's cholesterol levels.
The idea that certain types of cholesterol can cause dangerous plaques to build up in our blood vessels is one of the pillars of mainstream medicine.
There are several different types of cholesterol particles in the blood.
A type called high-density lipoprotein (HDL), and it is associated with a reduced risk of heart attacks, and this is sometimes known as good cholesterol, and bad cholesterol is a type called low-density lipoprotein or "LDL", and it is also believed that another type of fatty molecule called triglycerides Harmful as well.
If you see a lipid analysis, what does HDL mean?
HDL
is the beneficial type that collects cholesterol deposits from the lining of the arteries and returns them to the liver, thus maintaining the health of the heart and arteries.
Obesity
Source: Wikipedia pic.twitter.com/rNDrboqHCf
- Tahoor Charitable Society (@Tahoor Charity) May 24, 2019
Some people who follow low-carb diets see levels of bad cholesterol rise significantly.
Although they appear to be in the minority, the number of these "excessive respondents", as they are called, is unclear.
Westman estimates that only a small percentage of people who try such diets will be hyperresponsive.
In one of his experiments from 2004, two people out of 59 randomly selected withdrew to low-carb because of their higher levels of bad cholesterol.
Westman and others say they learn most often about this response in relatively lean and muscular people, and he thinks he may hear about more of these conditions now, because low-carb intake is increasingly being adopted as a long-term approach to healthy eating rather than just a short-term strategy for losing weight. the weight.
You don't have to be skinny and problematic to have an over-response, as Phippan Bhardwage, a family physician in Wokingham, UK, noted high harmful cholesterol in two out of 38 of his patients who started eating low-carbohydrates for diabetes, says Bhardwaj. Command. "
The strange thing about hyper-responders is that while the LDL level rises, other health indicators tend to move in the right direction.
These include high-density lipoprotein (HDL), triglycerides, blood pressure, and many other measures related to glucose and insulin response.
This was the case for two of Bhardwaj's hyper-responders.
We were reassured by scanning the arteries to the heart to check for any plaques. "You see what is really happening under the hood. They were perfectly fine," he says.
The fact that some people see elevated levels of bad cholesterol on a low-carb diet while other parameters improve now leads some to question whether low-density fats really are a major determinant of risk to our hearts.
Many of the cases against this type of cholesterol are based on population studies of the past few decades, which have found that people with high levels of low-density lipids were more likely to have heart attacks.
But these types of studies can only find correlations between blood markers and health outcomes, and not prove that one leads to the other.
The root cause of heart disease could be another factor in which low-density lipid levels rise as a side effect.
The main suspect for this other thing is "insulin resistance," says Gary Tobies, a longtime advocate of carbohydrate reduction and has just written a book called "On the Keto."
This idea does not conflict too much with our current understanding of the root causes of heart disease.
Doctors are already aware that type 2 diabetes, obesity, and heart disease are often associated with "metabolic syndrome".
However, instead of heart disease being a disorder of "damaged channels" where arteries get clogged because we consume so much fat, the real problem may be a preparation for insulin resistance, which in turn boosts insulin levels, fat storage and heart disease.
"If this is true, then the medical research community made a huge mistake and we still need to fix it," says Tobies.
Another important piece of evidence that made us believe that low-density lipids is an important factor is the success of cholesterol-lowering drugs called statins that reduce heart attack rates according to multiple randomized trials, and are the most respected type of medical studies.
But many other drugs that lower LDL levels do not protect against heart attacks, and statins have many effects on the body, including reducing low-level systemic inflammation.
And statins may actually protect the heart through their anti-inflammatory effects.
Some say it is the arrival of statins that has put us so focused on LDL levels.
"Doctors only spend 5 or 10 minutes with a patient, so it's a good idea to write a prescription and track your low-density lipoprotein," says Brett Sher, an American cardiologist and medical director of the Diet Doctor website that promotes low-carbohydrate eating.
While practicing clinicians focus on low-density lipoprotein levels for their patients, cardiologists studying heart health biomarkers these days are debating whether low-density lipoprotein levels are really the most important indicator, or whether things like the ratio of total cholesterol to lipoprotein are debating. High-density, or the ratio of high-density triglycerides to high-density lipoprotein, will be most beneficial.
The over-responders would be fine if their biomarkers were judged on either of these two measures: high levels of HDL protein and low levels of triglycerides.
One experiment often used to confirm the risks of low-carb diets found that people with type 2 diabetes saw LDL levels rise by an average of 10% after a year of dieting.
However, there was an improvement in most of the other 25 health indicators tracked such as weight, blood pressure and HDL.
The participants' overall risk of developing heart disease decreased by 12%.
To illustrate how confusing this is to the public, this particular trial is cited as evidence against low-carbohydrate intake - because LDL levels have increased - and in favor of the diet as the overall risk is reduced.
Sher admits that we don't yet know how dangerous it would be if people following a low-carb diet had higher levels of LDL while other health indicators improved.
What we need is more studies that track excessive responders over time to find out if they develop heart disease.
Meanwhile, where does the uncertainty leave the average person wanting to lose just a few pounds?
Westman says the appearance of excessive responders should not stop people from trying a low-carb intake.
"That would be crazy, like telling someone not to take a useful drug because it sometimes has side effects."
On the other hand, unlike most medicines, we do not know how common this side effect is.
Trials tend to report normal changes in the LDL level of only the low carbohydrate group of respondents.
Despite the new enthusiasm for these diets among diabetes and obesity specialists, many cardiologists and dieticians are still critical of the matter.
A 2019 joint report on heart disease prevention from two U.S. states of heart disease said that low-carb diets are associated with higher death rates.
"The evidence remains weak on the long-term cardiovascular safety of a ketogenic diet," says Donna Arnett of the University of Kentucky, who is the guidelines' author.
"There is conflicting evidence," says Tracy Parker, a nutritionist at the British Heart Foundation. We know that saturated fat increases blood cholesterol.
Parker says that if people are intent on cutting back on carbohydrates, a safer bet is to replace the carbs with oils from plants and fish.
However, she acknowledges that this would make what is already a restricted diet more restrictive than that, because people would have to avoid all starchy and sugary foods but also meat and dairy products.
It doesn't mean eating low carbs is the only way to lose weight, says Roy Taylor, a diabetes specialist at the University of Newcastle in the UK.
Taylor pioneered the use of meal replacement drinks to help people lose weight quickly when following a low-calorie, low-fat diet, and he showed that if people with type 2 diabetes could lose about 15 kilograms in this way, and that he could also introduce diabetes. In the healing phase.
Unfortunately, none of the experiments that compared low-carb diets to low-fat diets lasted long enough to find out which method helps people maintain weight for a long time.
In fact, a recent review of many different types of food, including low-carb, low-fat and the Mediterranean diet, concluded that most people regained the weight they lost 12 months after they started anyway.
Of course not everyone can stick to a low-carb diet, some find they miss out on bread, rice and pasta.
Mike Lynn of the University of Glasgow, UK, who has worked with Taylor on a meal replacement diet strategy, says his obesity clinic now offers advice on both low-fat and low-carb diets. “People can use whatever they can to lose weight in a form,” he says. Better, whether it is a low-fat or low-carb diet, we did not find a difference in weight loss. "
The idea that different people may find better results in different foods is supported by recent research indicating that there is no such thing as a healthy one-size-fits-all diet.
Alternatively, genetic factors, habits and gut microbiomes may influence how our bodies handle the nutrients in our diet.
However, even if the most we can say about low-carb diets is that they work for weight loss and are safe for most people, this would still be a marked change from the previous strict belief that saturated fat is an inevitable pathway to a heart attack.
For now, there are more questions than answers.
But even before the advent of the low-carb diet, there was growing concern that the cholesterol theory of heart disease stood on shaky ground, and now the hyper-responders make it seem more wobbly.
"There is a possibility that this subset of patients may upend the philosophy that low-density lipoprotein (LDL) is the most important risk factor for heart disease," says Sher, "I am cautiously optimistic."
Low-carb diets are controversial as a way to lose weight, but they have been used for decades to treat severe epilepsy in children and are exploring other conditions.
With epilepsy, avoiding carbohydrates so that the body enters a state called ketosis, that is, when cells are forced to switch to using fats for energy, it causes many metabolic changes within the brain cells.
It may work by making brain cells less "excited" or susceptible to uncontrolled signaling, or by reducing the damage to brain cells when seizures occur.
Ketogenic diets can be very beneficial for children whose epileptic seizures cannot be controlled with epilepsy medications, says Bhai Van de Boer, a spokesperson for the British Dietetic Association, who helped children with this diet at Great Ormond Street Hospital in London. .
The ketogenic diet is currently being investigated as an add-on to conventional cancer treatments.
And it appears that it makes tumor cells more sensitive and vulnerable to the effects of chemotherapy and radiation, because those cells have transformed so that they rely on glucose for energy.
The metabolic changes that diet introduces into brain cells may also protect the brain from neurological conditions such as Parkinson's disease and Alzheimer's disease, and promising individual case studies have been conducted in this regard.
But in these cases, scientific research is still in its infancy.
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This article is translated from New Scientist and does not necessarily feature Maidan.