After the tremendous success of the keto diet, many cardiologists and nutritionists began 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.

Then these revisions led to the introduction of the keto diet in the treatment of diabetes and cancer, as it became clear to the scientists that the cells of cancerous tumors feed on glucose from bread and starches in general, and that cutting bread with bread is a possible solution to stop the progression of the disease and even cure it.

Countless diets come and go every day, but these days there's a system we don't stop hearing about. Whether you call it a low-carb diet, Atkins diet, keto or paleo, the principle is the same: reduce starchy foods and be full of fats and protein. .

Obesity and diabetes specialists are increasingly relying on low-carb diets, and an increasing number of trials are showing that this approach helps people lose weight at least as much as traditional low-fat and low-calorie diets, and more people are eating this way not to lose weight but because they see it as more health.

However, many doctors warn of the dangers of eating low carbs, and point to large population studies linking low-carb diets to an increased risk of heart attack, stroke and early death.

Confusingly, these warnings do not seem to align with clinical trial results, which are generally a better type of medical evidence than population studies.

Many have now shown that low-carb diets in general 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 do see an increase, other indicators of heart health usually improve.

It's so confusing, that some question whether the causes of heart disease are wrong.

“It made me wonder if I believed in the cholesterol hypothesis at all,” says Eric Westman, an obesity specialist at Duke University in North Carolina.

With increasing rates of obesity and 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 lost weight on his own this way and recommended them in diet and cookbooks.

His advice to eat steak, cream, and butter while avoiding most fruits and vegetables made him a pariah from the cure.

Critics said people wouldn't be able to hold on to it, and if they did it would kill them, says Westman, who studied under Atkins.

New York cardiologist Robert Atkins before and after the diet

For many people, low-carb diets obviously work. By the early 1990s, randomized trials showed that such diets were as good, at least as low-fat, for weight loss, and often just slightly better. In one trial, people on 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 are generally moving in the right direction, says Westman, who led some of those studies.

What is the explanation? The central idea is that controlling weight requires more than just counting calories. For starters, the same amount of calories from fat or protein makes people feel fuller than if that amount came from carbohydrates, which explains why people on low-carb diets experience less hunger than those on low-fat diets. Westman's studies helped show that although most people on low-carb diets don't count calories, they tend to consume only 1,200-1,500 calories per day, well below 2,000 calories per day for women and 2,500 for men. "They eat less because they're not hungry," Westman says.

Another key insight is about what happens when we change the body's main energy source. We usually feed our cells 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, which tells cells to start taking in, 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've got an influx of calories and need to get rid of 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 cell type, 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 go several hours without eating any carbohydrates.

The reason for having low carbs is to reduce insulin secretion and provide as much ketones as possible.

For most people, the transition into what's known as "ketosis" happens within a few days of cutting down on lots of carbohydrates.

Eating very low levels of carbohydrates is also known as the ketogenic diet.

In addition to people trying to lose weight, many people have adopted a low-carb or keto diet because they see it as a way to live healthier and extend their lifespan. Some followers of ketosis believe that getting into ketosis has a range of metabolic benefits, including warding off cancer and Alzheimer's disease although there is no good evidence for this. Low-carbohydrate diets are used by neurologists to induce ketosis as a treatment for certain forms of epilepsy, and are examined in other conditions as well.

What has recently given low carb intake more legitimacy 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 dangerously high 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.

Medical doctrine says that because diabetes increases the risk of heart disease, it is very important that sufferers avoid saturated fats, which are mainly found in red meat and dairy products, as they are believed to raise cholesterol and clog arteries.

The NHS advice in type 2 diabetes is that people should reduce fat to a minimum and eat starchy foods like pasta, for example.

But this ignores the fact that diabetics may find two benefits in low carbs. In addition to losing weight that improves their insulin sensitivity, avoiding starch and sugar reduces hyperglycemia. Remember that starches are 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 might say that while a few days of low-carb eating leads to 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 10 randomized trials found that low-carb diets were more effective than low-fat diets at improving glycemic control in people with diabetes during the first year, but the differences disappeared after that. But there is evidence that for those who keep it up, the health benefits can persist in the long term, such as a study of 128 people with type 2 diabetes who went to low-carb counseling sessions run by David Unwin, a family physician in Southport in United kingdom. After an average of two years' follow-up, about half were able to stop taking all diabetes medications.

Many are starting to question whether "bad cholesterol" really poses a risk to heart health because of findings like these, and diabetes doctors and patient support groups are beginning to question the low-fat doctrine as well.

Authorities such as Diabetes UK and Diabetes Australia now say eating low-carb is a viable option for weight loss.

Ten years ago, we wouldn't have heard that.

Then the American Diabetes Association went one step further last year and said that of all the dietary strategies, low-carb had the most supporting evidence for better glycemic control.

However, as more people adopt this method of eating, questions about its safety have been renewed.

In some cases, low-carb diets can cause a worrying 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 a pillar of mainstream medicine.

There are several different types of cholesterol particles in the blood;

A type called high-density lipoprotein "HDL", which is associated with a lower risk of heart attack, and this is sometimes known as "good" cholesterol, and "bad" cholesterol is a type called "low-density lipoprotein" or "LDL", and another type of fat molecule is also believed to be called triglycerides. harmful as well.

If you see a lipid test, what does HDL mean?


It


is the useful type of HDL 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.

#obese

Source: Wikipedia pic.twitter.com/rNDrboqHCf

— Tahoor Charitable Society (@Tahoor_sa) May 24, 2019

Some people who follow low-carb diets see their levels of bad cholesterol rise significantly.

Although they appear to be in the minority, the number of these "hyper-responders", 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 out of 59 randomized people withdrew to low-carb because their bad cholesterol levels were high.

Westman and others say they often learn about this response in people who are relatively thin and muscular, and he thinks he may now hear about more of these cases, because eating low-carb is increasingly being adopted as a long-term approach to healthy eating rather than just a short-term strategy to lose weight. weight.

You don't have to be skinny and troubled to have an excessive response. Vipan Bhardwaj, a family physician in Wokingham, UK, observed high LDL cholesterol in two of his 38 patients who started eating low-carb for diabetes. matter."

What's strange about hyper-responders is that while LDL 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.

Such was the case for two of Bhardwaj's hyper-responders.

His reassurance was increased by scanning the arteries to the heart to check for any plaques. "You see what's really going on under the hood," he says. "They were perfectly fine."

The fact that some people see a rise in levels of bad cholesterol on a low-carb diet while other parameters are improving is now leading some to wonder if LDL is really a major determinant of risk to our hearts.

Much of the case against this type of cholesterol was built on population studies in the past few decades, which found that people with higher levels of LDL were more likely to have heart attacks.

But these types of studies can only find associations between blood markers and health outcomes, and not prove that one leads to the other.

The root cause of heart disease could be something else in which LDL levels are elevated as a side effect.

The main suspect for this other thing is "insulin resistance," says Gary Tobbis, an American science journalist who has been a longtime advocate of reduced carbs and has just written a book called "On Keto."

This idea does not contradict our current understanding of the root causes of heart disease.

Doctors already know that type 2 diabetes, obesity and heart disease are often associated with metabolic syndrome.

However, instead of heart disease being a disorder of the "damaged ducts" where arteries become clogged because we consume too much fat, the real problem may be predisposition to insulin resistance, which in turn boosts insulin levels, fat storage, and heart disease.

"If true, then the medical research community has made a huge mistake and we still need to fix it," says Tobis.

Another important piece of evidence that led us to believe that LDL is an important factor is the success of statins called statins that reduce heart attack rates according to multiple randomized trials, the most respected type of medical study. But many other drugs that lower LDL levels don't protect against heart attacks, and statins have many effects on the body, including relieving low-level systemic inflammation. And statins may actually protect the heart through their anti-inflammatory effects.

Some say it's the arrival of statins that has us focusing so heavily on our LDL levels. "Doctors only spend 5 or 10 minutes with the patient, so it's convenient to write a prescription and keep track of LDL," says Brett Sher, an American cardiologist and medical director of the website Diet Doctor that promotes low-carb eating.

While practicing physicians focus on their patients' LDL levels, cardiologists who study biomarkers of heart health these days debate whether LDL levels really are the most important indicator, or whether things like the ratio of total cholesterol to lipoprotein High-density lipoprotein, or triglyceride-to-high-density lipoprotein ratio, would be most beneficial. Over-responders would be fine if their biomarkers were judged on either of these two scales: higher levels of high-density lipoprotein, lower levels of triglycerides.

One trial often used to confirm the dangers of low-carb diets found that people with type 2 diabetes saw LDL levels rise by an average of 10% after a year of following the diet. However, there was an improvement in most of the other 25 health indicators that were tracked, such as weight, blood pressure and high-density lipoprotein. The participants' overall risk score for heart disease was reduced by 12%.

To illustrate how confusing this is to the public, this particular trial was cited as evidence against eating low carbs - because LDL levels have gone up - and in favor of this diet as overall risks are down.

Cher acknowledges that we don't yet know how serious it is if people on a low-carb diet experience higher LDL levels while other health indicators improve.

What we need is more studies that track hyper-responders over time to see if they develop heart disease.

In the meantime, where does the uncertainty leave the average person who just wants to lose a few pounds?

Westman says the emergence of hyper-responders shouldn't stop people from trying low-carb eating.

“That would be crazy, like telling someone not to take a helpful drug because sometimes it has side effects.”

On the other hand, unlike most medications, we don't know how common this side effect is.

Trials tended to report normal changes in LDL only than the low-carbohydrate responders group.

Despite the newfound enthusiasm for these diets among diabetes and obesity specialists, many cardiologists and dietitians remain critical of it.

A joint 2019 report on heart disease prevention from two US cardiologists said low-carb diets are associated with higher mortality rates.

"Evidence is still weak about the long-term cardiovascular safety of the ketogenic diet," says Donna Arnett of the University of Kentucky and one of the authors of the guidelines.

“There is conflicting evidence,” says Tracy Parker, a dietitian at the British Heart Foundation, as we know saturated fats raise blood cholesterol. Parker says that if people are intent on reducing their carb intake, the safest bet is to replace carbs with oils from plants and fish. However, she acknowledges that this would make what is already a restricted diet even more restrictive, because people would have to avoid all starchy and sugary foods but also meat and dairy.

It's not that eating low carbs is the only way to lose weight, says Roy Taylor, a diabetes specialist at Newcastle University in the UK. Taylor pioneered the use of meal replacement drinks to help people lose weight quickly on a low-calorie, low-fat diet, and showed that if people with type 2 diabetes could lose about 15 kilograms this way, he could also introduce diabetes. in the healing phase.

Unfortunately, none of the trials comparing low-carb diets with low-fat diets lasted long enough to see which method helped people maintain weight for the long haul. In fact, a recent review of several different diets, including low-carb, low-fat and Mediterranean diets, concluded that most people regained the weight they lost 12 months after starting it anyway.

Of course not everyone can stick to a low-carb diet, some find they miss bread, rice and pasta.

Mike Lane of the University of Glasgow, UK, who worked with Taylor on the meal replacement diet strategy, says his obesity clinic now offers advice on both low-fat and low-carb diets. Better, whether it was a low-fat or low-carb diet and we didn't find a difference in weight loss."

The idea that different people may find better results in different foods is supported by recent research that suggests there is no such thing as a healthy, one-size-fits-all diet.

Alternatively, genetics, 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, it would still be a marked change from the previous strict orthodoxy that saturated fats are an inevitable path to heart attack.

At the moment, there are more questions than answers.

But even before the advent of the low-carb diet, there were growing concerns that the cholesterol theory of heart disease was on shaky ground, and now hyper-responders are making it seem even more volatile.

“There is a possibility that this subgroup of patients may overturn the philosophy that LDL is the most important risk factor for heart disease,” Scheer says, and I am cautiously optimistic.

Low-carb diets are controversial as a method for weight loss, but they have been used for decades to treat severe epilepsy in children and are being explored for other conditions.

In epilepsy, avoiding carbohydrates so that the body enters a state called ketosis, when cells have to switch to using fats for energy, causes many metabolic changes within brain cells.

It may work by making brain cells less "excitable" or prone to uncontrolled firing, or by reducing damage to brain cells when seizures occur.

Ketogenic diets can be very beneficial for children whose seizures cannot be controlled with epilepsy medication says Bhai van de Boer, a spokesman for the British Dietetic Association, who helped children on the diet at Great Ormond Street Hospital in London .

The keto diet is currently being investigated as an additional option for conventional cancer treatments.

They appear to make tumor cells more sensitive to the effects of chemotherapy and radiation, because those cells have been converted to rely on glucose as an energy source.

The metabolic changes that diet introduces to brain cells may also protect the brain from neurological conditions such as Parkinson's and Alzheimer's diseases, and promising individual case studies have been conducted in this regard.

But in these cases, scientific research is still in its infancy.

—————————————————————————————-

This article is translated from New Scientist and does not necessarily represent the site of Medan.