Category: Low Fat

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Low Carb Diets and Heart Disease – What Are We Afraid of?

I find it extraordinary how carbohydrate restriction is repeatedly rejected by the medical community as an alternative approach for obesity, metabolic syndrome and type 2 diabetes.

Obesity has reached epidemic proportions in many countries around the world. Diabetes and other obesity related disorders have become increasingly common.

Public health organizations and medical societies usually advocate a low-fat, high-carbohydrate, energy-deficient diet to manage weight. Nonetheless, clinical experience and scientific studies indicate that other approaches may be more effective.

The main argument against carbohydrate-restricted, high-fat diets are concerns regarding their long-term safety. Most such diets encourage increased consumption of animal products and therefore they often contain high amounts of saturated fat and cholesterol. It has been suggested that this may cause unfavorable changes in blood lipids and thereby increase the risk of heart disease. Therefore, several professional organizations have cautioned against the use of low-carbohydrate, high-fat diets.

According to a statement from the American Heart Association AHA, updated January 2012, “eating large amounts of high-fat foods for a sustained period raises the risk of coronary heart disease, diabetes, stroke and several types of cancer.”

An older statement from the Heart and Stroke Foundation of Canada claims that ” low carbohydrate diets often lack vitamins and are low in fibre. A low fibre diet can result in constipation and can increase your risk of colon cancer. Low carbohydrate diets tend to replace carbohydrate with fat and protein. High intake of protein can result in large amounts of calcium in the urine, and loss of bone mass. High intake of fat, particularly saturated and trans fat, can lead to atherosclerosis, heart disease or stroke”.

These statements are based on observational data at best. Randomized clinical trials generally don’t support these conclusions. In fact, low carbohydrate diets have demonstrated their therapeutic value in numerous studies, and often outperform other diets when comparisons are made. Nonetheless, they are still ignored by governments and medical societies. Keep in mind though, that carbohydrate restriction is a matter of definition. Some diabetic associations have accepted moderate carbohydrate restriction as an alternative approach for weight loss in type 2 diabetes.

Doctors, cardiologists included, commonly recommend low-fat, high-carbohydrate diets to patients with heart disease, as well as for cardiovascular prevention. Limitation of saturated fats and cholesterol is advocated. This is what doctors are urged to do by clinical guidelines. The guidelines are written by specially selected experts and published by professional organizations.

Interestingly, there is often no mention of individual differences between patients. The low-fat, low saturated fat, low cholesterol, high-carbohydrate approach is recommended for all. It doesn’t matter whether you have high blood pressure, whether  you are obese or overweight, have the metabolic syndrome, or whether you have diabetes.

I have nothing against low fat diets. Look at the DASH diet for example. Extensive research indicates that this diet lowers blood pressure and cholesterol, and is associated with lower risk of several diseases, including heart disease. Furthermore, it was recently suggested that the DASH diet may be used for weight loss as well. I would be very satisfied if may patients would stick to the DASH diet. I usually urge them to do so. I am sure it benefits their health. The same thing can be said about plant based diets. Furthermore, I very often recommend a Mediterranean type diet to my patients. There is a lot of scientific date supporting the use of this diet for cardiovascular prevention as well as for patients with heart disease.

Low Carb, Obesity and Metabolic Syndrome

The role of diets takes on a different perspective when it comes to obese patients, and those with metabolic syndrome, where weight loss is a priority. For years I have struggled with the low-fat, high-carbohydrate, energy-deficient dietary approach to manage these conditions. Simply put, the results have been disappointing. Often weight loss is limited and not sustained, and there are very limited improvements in metabolic function. However, I might admit the lack of result is more often due to lack of compliance than something else. Maybe we provide instructions and recommendations that patients are unable to comply with, no matter how hard they try.

 

I have found that people suffering from obesity or metabolic syndrome are much more likely to lose weight and improve their metabolic function on a low-carb, high-fat diet.

However, my clinical experience is that the effects of such a dietary approach on blood lipids are a bit hard to predict. Commonly there is an elevation of total cholesterol and LDL-cholesterol (“bad cholesterol”) which may be considered harmful. However, at the same time there is most often an elevation of HDL-cholesterol (“good cholesterol) and triglycerides are lowered.

So the question is; Should I not recommend a dietary approach that works in terms of weight loss and metabolic control, because there may be a slight elevation of LDL-cholesterol? According to the medical associations and the clinical guidelines, I should not.

Low Carb Diets and Heart Disease – The Scientific Studies

My purpose is not to go through all available scientific data on the issue of carbohydrate restriction and heart disease. However, I will try to convince you that the available data does not support the conclusion that low-carbohydrate diets are less safe than other dietary approaches for people who are obese, overweight or suffer from the metabolic syndrome.

The initial recommendations to avoid saturated fat and cholesterol were based on observations from epidemiological research. Some of this research was led by the famous American scientist, Ancel Keys. In a personal reflection from 1995

Keys wrote: “These observations led to our subsequent research in the Seven Countries Study, in which we demonstrated that saturated fat is the major dietary villain.” Keys observed that death rates were related positively to the average percentage of dietary energy from saturated fatty acids, but negatively to dietary energy percentage from monounsaturated fatty acids. In short; saturated fats seemed to increase risk, while monounsaturated fats appeared to lower risk.

Since then, an independent association of saturated fats with the risk of heart disease has not been consistently found in epidemiologic studies. Replacing saturated fats with carbohydrates has not been shown to be beneficial. In fact, replacement of saturated fats with refined carbohydrate can worsen blood lipids when insulin resistance is present, by increasing triglycerides, the number of small LDL particles, and by decreasing HDL-cholesterol. Some studies have indicated that replacing saturated fat with monounsaturated or polyunsaturated fat may be beneficial, although the latter was not supported by the recently published Sidney Diet Heart Study.

The relationship between the consumption of fat, saturated fat in particular was studied in the Swedish Malmö Diet and Cancer Study published in 2007. In this large prospective observational study, no trend towards higher cardiovascular event risk for women or men with higher total or saturated fat intakes, was observed. This study was later included in the much cited Siri-Tarino meta-analysis published 2010, showing no significant evidence for concluding that dietary saturated fat is associated with an increased risk of heart disease.

A number of randomized clinical trials have compared low-carbohydrate diets with other dietary approaches. In many of these studies, low carb diets have resulted in more short-term weight loss in healthy women, individuals with severe obesity with high prevalence of the metabolic syndrome and type 2 diabetes, overweight adolescents, overweight individuals with hyperlipidemia, and  premenopausal women, compared with low-fat diets. Furthermore, negative effects on blood lipids with low-carbohydrate diets were not observed in these studies and markers of the metabolic syndrome were generally improved.

Most of these randomized trials are short term studies. Thus, the long-term effects of low-carbohydrate diets still remain to be clarified. Recently, it has been suggested that such diets may be harmful.

In a systematic review and meta-analysis of observational studies, published November last year, Noto and coworkers found that low-carbohydrate diets were associated with a significantly higher risk of all-cause mortality. However, they did not find an association between low-carb diets and the incidence of, and mortality from cardiovascular disease. The authors acknowledge that their analysis is based on limited observational studies, and that large-scale trials on the complex interactions between low-carbohydrate diets and long-term outcomes are needed. It is also necessary to point out that there was a substantial difference between studies, regarding both study design and definitions. Such heterogeneity may make meta-analysis problematic.

A Few Final Words

There are many different versions of low-carbohydrate, high-fat diets. Some promote the consumption of saturated fat, while others don’t. For a patient with heart disease or someone with elevated cholesterol, I usually recommend monounsaturated fat and polyunsaturated fats rich in omega-3. I find that using the Mediterranean approach, when selecting which fats to eat may be very helpful.

Although it does not comply with guidelines, I commonly recommend individuals who are obese or suffer from the metabolic syndrome to cut down on carbohydrates and increase fats. In most instances, I find these recommendations very useful. I don’t recommend my patients to stay in ketosis for long periods of time. However, if they choose to do so, if they feel well, and if their health is improving, I find no reason to tell them not to.

If an obese person with metabolic problems manages to achieve weight loss and improve his or her metabolic function on a low carbohydrate diet, it is hard to understand how such an achievement may be harmful.

I look forward to the day when low-carb, high-fat diets are accepted by public health representatives and medical associations for the treatment of obesity, metabolic syndrome and type 2 diabetes.

The medical community, which I am a part of, accepts that drugs that lower cholesterol, and slightly reduce the risk of heart disease (although having considerable side effects, among them increased risk of diabetes) are given to 25 percent of adults in many countries around the world.

I find it a bit hard to accept that the same medical community does not accept and recommend a dietary approach for obesity and the metabolic syndrome, that causes weight loss, increases wellbeing and improves metabolic function, and indeed appears to outperform other diets in this respect.




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What Is the Best Diet for Type 2 Diabetes?

An interesting scientific paper on the efficacy of different dietary approaches in type 2 diabetes recently caught my eye. The study has not received much media coverage although it certainly addresses a question of importance to millions of people worldwide.

More than 20 million people in the US have type 2 diabetes. According to the International Diabetes Foundation (IDF), the number of people diagnosed with diabetes in the last twenty years has risen from 30 million to over 246 million, or about 7.3% of the world population. Approximately 90% of those have type 2 diabetes. Diet and nutrition play a central role in the well-being of all those people. 

The study, which is a systematic review, was published in a recent issue of the American Journal of Clinical Nutrition. A systematic review is an unbiased survey of all the scientific evidence available on a given question. In this case, Ajala and coworkers from Plymouth UK addressed the efficacy of different diets to induce weight loss and improve glycemic control and lipid profile among people with type 2 diabetes.

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Type 2 Diabetes and Prediabetes

Before we go further, let me touch on few basic issues, just for the sake of clarification. Type 2 diabetes is a chronic condition that affects the way our body metabolizes sugar (glucose). Glucose is the body’s primary source of fuel. With type 2 diabetes, the body either resists the effects of insulin — a hormone that regulates the movement of sugar into our cells — or doesn’t produce enough insulin to maintain a normal glucose level.

Glucose comes from two major sources, food and the liver. Our liver produces and stores glucose. When glucose enters the blood stream, insulin is released from the pancreas. Insulin enables sugar to enter the cells of the body where it is used for energy production. Without insulin, or when insulin resistance is present, glucose builds up in the blood stream. This is what happens in diabetes. Elevated levels of blood glucose may cause a number of symptoms, and increase the risk of developing heart disease and stroke.

It is not fully understood why people develop type 2 diabetes, but certain factors increase the risk. Overweight is a risk factor. However, many overweight and obese individuals never have diabetes, and many people with type 2 diabetes are not overweight or obese. If our body stores fat primarily in the abdomen, the risk of diabetes is higher than if the body stores fat elsewhere such as on our hips and thighs. Family history and physical inactivity also increase the risk of diabetes.

The risk of type 2 diabetes increases with age. Lately, type 2 diabetes has become increasingly common in children, adolescents, and young adults. The main goals of therapy are to improve glucose metabolism and thereby reduce blood sugar levels and to mitigate the risk factors for the main complications of diabetes, heart disease, and stroke. Overweight often contributes significantly to the development of type 2 diabetes. Therefore weight loss often plays a large role in the treatment of the disorder.

Prediabetes is a condition in which blood sugar level is higher than normal, but not high enough to be classified as diabetes. Left untreated, prediabetes often progresses to type 2 diabetes. There is good evidence showing that dietary modification can prevent the progression from prediabetes to type 2 diabetes. Howvever, the optimal dietary approach to type 2 diabetes is less clear. Before I discuss the recent study by Ajala and coworkers, let’s have a look at the background stage.

What Is the Best Diet for Type 2 Diabetes?

For some years, experts and scientists have debated what dietary approach is best to control and treat type 2 diabetes. Most regulatory authorities, like the British Diabetic Association, European Association for the Study of Diabetes (EASD), American Diabetes Association (ADA), Canadian Diabetes Association and many more usually recommend a carbohydrate intake of 50-60% of total energy intake, total fat intake less than 30% of energy, with restriction of saturated and trans fat intake. Some experts believe there is insufficient evidence to justify these recommendations.

Almost five years ago, an international group of scientists and experts on diabetes, nutrition and carbohydrate metabolism published an overview paper suggesting a critical appraisal of the role of carbohydrate restriction in type 2 diabetes mellitus and the metabolic syndrome. The authors pointed out that current nutritional approaches often emphasized a reduction in dietary fat.

They believed that such approaches often were ineffective, leading to more reliance on drug therapy. They argued that carbohydrate restricted diets were at least as effective for weight-loss as low-fat diets and that the substitution of fat for carbohydrate was beneficial for the risk of cardiovascular disease. Furthermore, they provided evidence suggesting that carbohydrate restriction improved control of blood glucose and reduced insulin fluctuations. They believed the recommendation to reduce the intake of saturated fat in type 2 diabetes lacked scientific evidence.

The authors concluded: “Finally, while no systematic study of clinical practice has been done, anecdotal evidence suggests that carbohydrate restriction is a common clinical recommendation for diabetes. We believe that there is a need to codify these recommendations in light of current evidence.”

In the recent systematic review by Ajala and coworkers, data was collected from all studies published up to July 2011 that compared low carbohydrate, vegetarian, vegan, low glycemic index (GI), high fiber, Mediterranean, and high protein diets with control diets including low-fat, high-GI, ADA diet, EASD diet, and low-protein diets. Only randomized controlled trials with an intervention lasting longer than six months were selected. A total of 20 studies including 3073 individuals fulfilled the defined criteria and were selected for the metaanalysis. Measured outcomes were HbA1c (which reflects glucose control), difference in weight loss, and changes in HDL-cholesterol (“good cholesterol”), LDL-cholesterol (“bad cholesterol”) and triglycerides.

The low carbohydrate, low-GI, Mediterranean, and high protein diets all led to a greater improvement in blood glucose control (HbA1c) compared with their respective control diets, with the largest effect seen with the Mediterranean diet. Low-carbohydrate and Mediterranean diets led to a greater weight loss compared with their control diets. Low carbohydrate, low-GI, and Mediterranean diets all led to an elevation of HDL-cholesterol. Only the Mediterranean diet led to a significant reduction in triglycerides. High protein diets had no effects on markers of lipid profile. One study from their review compared the effects of a vegan diet to the low-fat ADA diet. The vegan arm had a significantly lower levels of total cholesterol, LDL-cholesterol, and HbA1c, indicating better glycemic control by the vegan diet. Similar results were obtained in one study that compared the effect of a vegan diet with the EASD diet, with more weight loss on the vegan diet.

Ajala and coworkers conclude that their review provides evidence that modifying the amount of macronutrients can improve glycemic control, weight, and lipids in type 2 diabetes. In their analysis, low carbohydrate diets appeared to provide superior weight loss, better control of blood glucose, and better lipid profile, compared with low-fat diets. The authors also conclude that vegan and vegetarian diet may improve glucose control and promote weight loss in type 2 diabetes.

The Mediterranean diet is rich in olive oil, legumes, unrefined cereals, fruit, and vegetables, low in meat and meat products, and with moderate contents of dairy products (mostly cheese and yogurt), fish and wine. The total fat in this diet is typically 25-35% of calories, with saturated fat less than 8% of calories. The meta-analysis indicates that a Mediterranean diet provides better control of blood glucose, greater weight loss, and a more favorable lipid profile compared with a conventional diet and ADA diet.

A meta-analysis of such widely different studies may be problematic. For example, the control diets differed significantly between studies and the duration of the studies ranged between six months and four years. The definition of a low carbohydrate diet varies between studies. While the authors acknowledge the limitations of their study, they believe that low carbohydrate, low-GI, Mediterranean and high-protein diets should be considered in the overall strategy of diabetes management.

What is the best diet for type 2 diabetes?  Although there is probably not a simple answer, the question reflects one of the main challenges of modern medicine. It is likely that our dietary recommendations will have to be tailored to the needs of the individual. A one-size-fits-all approach is unrealistic. Although not providing any definitive answers, the study by Ajala and coworkers is an important contribution to our understanding of this highly important issue.

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Diet or Drugs to Prevent Heart Disease

The risk of heart disease has been associated with countless different things.

Smoking, diabetes, high blood pressure, overweight, obesity, sitting and watching TV, eating too much fat, eating too much sugar, not eating certain fats, eating meat, not eating fish, eating too much animal fat, eating cholesterol, eating saturated fat, eating trans fats, high blood cholesterol, high LDL-cholesterol, inflammation, family history of heart disease….

Is it really possible to avoid being hit by this dreadful disease, the most common cause of death and disability worldwide?Should we change our lifestyle? How can we improve our diet? Should we take drugs for prevention?

The risk of heart disease increases with age. So, if we become old enough, we will probably have heart disease sooner or later, and most likely die from it. But that is not necessarily a bad thing. We all have to die from something. Dying from something else is not a goal by itself.

So maybe we would be more accurate if, instead of aiming at preventing, our goal was to delay the onset of heart disease. However, defining our goal is probably less important than defining the methods to achieve it.

A huge number of healthy adults will have heart disease in the next ten years. Many will be treated with drugs, some will have angioplasty and stents, and some will have open heart surgery. Many will die from the disease. A substantial number will be left with severe disability. Many will not be able to work, and many will not enjoy the quality of life they had before the disease hit them. So, I presume we all agree that delaying the onset of heart disease is a worthwhile target.

Who should worry about getting heart disease? Probably everybody. But, who should worry the most? Who is most likely to be struck by heart disease in the next few years?

This is where it comes to the so-called risk factors. If you have many risk factors, the risk of having a heart attack or stroke becomes higher. The strongest risk factors are smoking, diabetes, high blood pressure, high levels of LDL-cholesterol, low levels of HDL-cholesterol, overweight or obesity, and family history of premature coronary artery disease. If you don’t have any risk factors, your aim should be to avoid them at all costs. But, if you have some of these risk factors, what can you do?

A Visit to Dr. Oxenhaler

Let’s assume you are a responsible person (you probably are by the way, because you are reading my blog), and you want to do everything you can to delay the onset of heart disease.

Maybe your father had a heart attack in his fifties. Maybe you have gained a bit of weight, and maybe your cholesterol level is a bit too high. So, you decide it’s time to have a chat with your general practitioner, Dr. Oxenhaler, the family doctor. Last year he put you on a drug to lower your blood pressure. This time, you are better prepared for your visit because you have been reading my blog.

You are sitting in front of Dr. Oxenhaler in his office. He just finished measuring your blood pressure, and now he is watching your blood work on his computer screen. This is how the conversation might evolve.

‘Is there a specific reason you decided to come to see me. Have you been having chest pain or discomfort of any kind?’
‘No Dr. Oxenhaler. I was just worried. I’ve been reading lots of stuff about heart disease on the internet. I was wondering what I should do to avoid having a heart attack.’
‘Well, I guess you should be a little bit worried, but I’m glad you care. That’s the first step. Your blood pressure is fine, thanks to the medication I prescribed for you last year. However, your cholesterol is 277 mg/dl (6.9 mmol/L), that’s  way too high.’
‘How about my LDL cholesterol?’

Dr. Oxenhaler watches you carefully, his glasses sliding down on his nose. He takes a deep breath.

‘I see you’ve been reading. That’s good. Education is the key to better health. Your LDL cholesterol is 182 mg/dL (4.7 mmol/L), that’s also way too high. HDL-C, the good cholesterol is 40 mg/dL (1.0 mmol/L) which is too low. Considering your family history and your history of high blood pressure, the risk is quite high. By using the Framingham risk calculator, I can see that your risk of having a heart attack in the next ten years is about 17 percent.’

You feel a little numb like the blood is draining from your head. Dr. Oxenhaler notices your paleness and becomes a bit more sympathetic.

‘Don’t be scared though. We can take care of this. Treatment is available. By putting you on a cholesterol lowering drug, we can lower your risk substantially.  Your cholesterol will go down and so will LDL-cholesterol. Your risk of heart attack will be much less’.
‘But I read that the effect of statin drugs is very small when they’re used for prevention in people who don’t have heart disease’.
‘That’s a misinterpretation. The risk reduction in the clinical trials is about 30 percent among high-risk individuals, which in my mind is quite substantial.’
‘You’re talking about relative reduction then Dr. Oxenhaler, aren’t you?´

There is a momentary pause. You catch a glimpse of surprise in his eyes. He looks at his watch and then back at you, a faint smile on his lips.

‘Yes, relative reduction, that’s correct’, he says.
‘I’ve read that statins have lots of side effects as well.’
‘Side effects are very uncommon. A small number of people have muscle pain, but it’s rare. Most people do not have any problems with cholesterol-lowering drugs.’
‘I read that some people have memory loss.’

He looks surprised.

‘I don’t recall any of my patients complaining of memory loss from statins.’

Now you can’t help wondering whether Dr. Oxenhaler is taking statins. You dismiss the thought immediately. You have to keep focus.

‘I’ve heard there is  more risk of diabetes if you take statins,’ you say,

He loosens his tie a bit, and he has stopped smiling. You’re aware that you’re using up a lot of his time. There are more patients waiting for him.

‘Let me just tell you that the benefits of statins definitively outweigh the risks’, says Dr. Oxenhaler.

But you’re not giving up.

‘Isn’t there something I can do by myself, change may diet or exercise more?’, you ask.
‘Diet and exercise is fine. Cut down on fats, especially saturated fat and don’t eat too much cholesterol. That’s helpful. But it won’t replace statin treatment when it comes to reducing your risk.’
‘I heard about a study published recently in The New England Journal of Medicine showing that a Mediterranean diet could lower the risk of heart attack and stroke if you have risk factors like I do’
‘You’re right indeed, but the effect is very small. Besides, diets are usually hard to stick with.’
‘I read that the relative risk reduction was about 30 percent on the Mediterranean diet compared to a low-fat diet. Isn’t that about the same effect that statins have in a similar population?’ Could a Mediterranean diet be an alternative to statin therapy?

Dr. Oxenhaler does not answer right away. He stares at the computer screen.

‘Very well, why don’t you try the Mediterranean diet for six months and then come visit me again. We’ll measure your cholesterol and decide what to do. If it’s still high, I definitively recommend statin treatment to cut your risk’, he says eventually, still watching the computer screen.

‘Isn’t it possible that the diet is helpful, although my cholesterol stays the same?’

Now he is looking at you again, more seriously than before. You can’t really tell whether he is annoyed or not.

‘If we are to succeed in lowering your risk of heart disease, we must lower your LDL-cholesterol. That’s a fact.’
‘But, I just read about the Women’s Health Initiative showing that reducing the intake of fat lowered cholesterol, but did not cut the risk of heart disease’.

Now he is up on his feet and offering his hand. He shakes his head in disbelief, but he is smiling again.

‘Please come back to see me in six months. Good luck with the Mediterranean diet. Go easy on the wine though. And for God’s sake don’t believe everything you read on the internet….’

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The War of the Diets – Low-Carb or Low-Fat

There is an ongoing war in the world of diet and nutrition. I call it the war of the diets. This war started many years ago and there just appears to be no end to it. Both sites are blaming each other for a huge number of casualties. Like in so many wars before, it is unlikely that there will be a winner. Books are published, articles written, videos and web pages flourish. Everybody’s expected to choose a side. 

History

Approximately three decades ago public health authorities decided that we should limit the amount of fat in our diet, primarily saturated fat, as it raises blood cholesterol and increases the risk of heart disease. The McGovern Committee’s report, “Dietary Goals for The United States” was published in 1977. Although possibly not based on solid scientific data, the committee’s main results were confirmed a few years later by the USDA. The main conclusion was that Americans should “avoid too much fat, saturated fat and cholesterol”.

Soon, the demonization of fat, primarily saturated fat, spread around the globe. Public health authorities in Scandinavia and the rest of Europe based their recommendation on the same arguments as the USDA. Although possibly a misinterpretation or oversimplification of the available evidence, in a few years time this led to something we could call the “low-fat mania”. The war of the diets had started. Food manufacturers began providing us with low-fat varieties of almost every food alternative we know. But, fat is difficult to replace, because it is commonly an essential component of good and tasty food. Instead of fat, different types of refined simple sugars, such as the famous high fructose corn syrup were used to make people like the fat-free varieties. The low-carb, low-fat controversy had risen to new heights. Carbohydrates were on the attack, fats were retreating.

As the years went by it became apparent that obesity was on the rise. People were getting fatter and fatter, despite all the low-fat food. Furthermore, type 2 diabetes seemed to be skyrocketing. Was it because we were not following the public health guidelines or was it because of the guidelines themselves? Or is it something completely different? What about inflammation, drugs and harmful chemicals in the environment. No wonder detox is becoming so popular.

Is it possible that the public authorities were wrong? Is it sensible to make general recommendations on diet and nutrition that applies for everybody? Should the obese, sedentary, middle-aged male follow the same diet recommendation as the thirty years younger normal weight, well-trained university student?

Furthermore, research and experience was starting to show that one of the most effective way for an obese or overweight person to lose weight was to cut down on carbohydrates and increase fat consumption. This concept was but forward by Dr. Robert Atkins in his book, The Atkins Diet Revolution, published 1972. Although severely criticized by the scientific and medical community at that time, the low carbohydrate, high fat (LCHF) concepts have survived and are still going strong. The LCHF supporters blame the “low-fat mania”, induced by public health recommendations for the current obesity epidemic which they say is all down to over consumption of sugars and carbohydrates. They are gaining more and more followers and some say the war of the diets may be turning.

One of the biggest culprits of the ongoing war is the concept that a calorie is a calorie. If you eat more than you burn, you will gain weight, if you burn more than you eat you will lose weight. If this is true, the cause of obesity is quite simply that people eat too much and exercise too little. The cure for obesity would also be very simple; eat less and exercise more.

However, there is a lot of evidence indicating that it is not all about calories. Some recent studies have indicated that weight loss seems to be greater on a low-carb diet than on a conventional low-fat diet that has the same number of calories. However, this is not true for all studies. Different macronutrients may possibly have different effects depending on individual factors, such as stature, body weight, age, metabolism, insulin resistance and level of physical exercise.

Carbohydrates

The cells of our body need a constant supply of energy in order to be able to function normally. This fuel is provided by the so-called macronutrients; carbohydrates, fat and protein. Carbohydrates are a very important source of energy for the human body. In some parts of the world, more than 80% of the energy consumed comes from carbohydrates. Public health authorities today recommend that 45 – 65% of our energy consumption should be provided by carbohydrates.

Before I go further, let’s clarify a few issues. How do we classify carbohydrates? Which carbohydrates are defined as sugars?

Carbohydrates are compounds that contain carbon, hydrogen and oxygen. They are generally classified as monosaccharides, disaccharides and polyscaccharadies. Saccharide means sugar, mono means one, di means two and poly means many. A monosaccharide contains one sugar molecule, a disaccharide contains two sugar molecules and a polysaccharide contains many sugar molecules.

Monoscaccharides and disaccharides are commonly termed sugars or simple carbohydrates, while polysaccharides are usually termed complex carbohydrates or starches. Cellulose and other fibers are also carbohydrates, but they do not provide energy as the body does not possess the enzymes necessary to digest them. Cellulose is commonly found in starchy foods, and although it does not provide energy, it contains vitamins, minerals and other nutrients. This is one of the reasons fiber is considered a healthy food choise. Sugar, however, provides only energy and does not contain vitamins, mineral or fiber.

The three monosaccharides found in food are glucose, fructose and galactose. Fructose is the one most commonly used as a food additive. It is the sugar molecule that has the sweetest taste. High-fructose corn-syrup is commonly added to foods when they are processed.

Three disaccharides are frequently used in food as well; sucrose, lactose and maltose. Sucrose is the typical, white table sugar and contains one molecule of glucose and one molecule of fructose. Sucrose is added to many processed foods.

Glucose and fructose may indeed work very differently for the human body. Glucose is metabolized by every organ in the body. It is our cells most important source of energy. If we don’t get glucose through our diet, our body makes it by a process called gluconeogenesis. Fructose is different as it can only be metabolized in the liver. Depending on our body’s need for energy, fructose will be metabolized to glucose, although this has been debated by some. However, if our energy needs are already met, which is often the case, fructose will be metabolized to fat.

By eating modern diet, rich in added fructose, we may indeed be overloading our liver. Much of the fructose delivered to the liver will be metabolized to fat. Through different complex mechanisms, over consumption of sugar, primarily fructose, may contribute to obesity and the metabolic syndrome as well as many other modern-day diseases like high blood pressure, cardiovascular disease, cancer and Alzheimer´s disease.

Carbohydrates are classified in different ways. They are often divided into two categories; sugars and starches. Sugars are also known as simple sugars or simple carbohydrates, and starches are referred to as complex carbohydrates. The widespread processing of carbohydrate-containing foods has given rise to some new terms. The term highly “processed” refers to foods that are primarily sugar or products made from grains that have been highly refined and sweetened. Examples of such foods are beverages and sugared cereals. In contrast, whole grains and foods made from them are referred to as minimally processed, fiber containing, or quality carbohydrates.

The Role of Insulin

Carbohydrate is the primary stimulus of insulin release from the pancreas. Insulin is necessary to promote glucose uptake by the cells of the body and to inhibit glucose output from the liver. There is a phenomenon called insulin resistance which is commonly associated with overweight, obesity and the metabolic syndrome. Insulin resistance  implies a diminished response to a given concentration of insulin. When insulin resistance is present, insulin may not be able to deliver its actions when carbohydrates are ingested. Insulin resistance is a precursor to type – 2 diabetes.

As insulin resistance develops, a number of physical and biochemical changes may occur. The liver turns more blood sugar into fat and blood levels of triglycerides rise. Blood pressure may rise above normal and levels of HDL cholesterol (the good cholesterol) may go down. Weight gain usually occurs, particularly around the center of the body. This situation may harbor inflammation. Inflammation has been associated with high levels of insulin, type – 2 diabetes and increased risk of cardiovascular disease. Studies have shown that low carbohydrate diets may promote weight loss and metabolic advantages among individuals with insulin resistance.

The Metabolic Syndrome

Approximately 30 percent of individuals in the United States have the so-called metabolic syndrome. The syndrome is defined as three of the following

  • Waist circumference > 102 cm (40 inches) in men and > 89 cm (35 inches) in women
  • Fasting triglycerides > 1.7 mmol/L (150 mg/dL)
  • HDL – cholesterol < 1.0 mmol/L (40 mg/dL) in men and < 1.3 mmol/L (50 mg/dL) in women
  • Blood pressure > 130/85 mm Hg or the use of blood pressure medication
  • Fasting glucose (blood sugar) > 6.1 mmol/L (110 mg/dL) or the use of diabetes medication

These derangements in combination increase the risk of cardiovascular disease. Insulin resistance appears to play a central role in the metabolic syndrome. Although avoidance of saturated fat is a primary target in the public health recommendations, it is likely that low carbohydrate diets may be much more effective among individuals who suffer from the metabolic syndrome.

Fat

Physiologically fats are long chains of carbohydrate molecules. The predominant fats in foods and in the body are triglycerides which are made up of three fatty acids attached to a glycerol molecule. Sterols, such as cholesterol and phospholipids, phosphate containing fats are also common. These fats compose the category known as lipids.

Fatty acids are chains of carbon and hydrogen, ending with a so-called carboxyl group. The lengths of the fatty acid chain vary from 4 to 24 carbons. The term saturated implies that no more hydrogen atoms can be incorporated into the molecule. The term unsaturated means that there is room for more hydrogen atoms, monounsaturated meaning that there is room for one such atom and polyunsaturated meaning that there is room for more than one atoms. Although so-called trans fatty acids may be found in small amounts in nature, they are usually produced synthetically by partial hydrogenation of polyunsaturated fatty acids. This is done in commercial food processing to make liquid oils more solid and to increase the shelf life of the product. A number of studies indicate that trans fatty acids negatively influence cardiovascular risk.

Two 18 carbons fatty acids are essential fatty acids – linoleic (omega-6) and alpha – linolenic acid (omega-3). The body cannot manufacture these fatty acids, so they must be consumed in the diet. Fortunately, those two essential fatty acid are widely found in food.

From a health perspective, there are certain fats that have been emphasized, because of the proposed effect on the risk of cardiovascular disease. Unsaturated fatty acids such as omega – 3 fatty acids are considered healthy options. Conversely it has been recommended that the consumption of saturated fatty acids be limited and that trans fatty acid consumption be as low as possible due to detrimental effect on the risk of cardiovascular disease.

Usually fats in food are a combination of saturated, monounsaturated and polyunsaturated fatty acids. We commonly tend to identify fat in the food based on the type of fatty acid that is predominant. We know that butter and steak for example predominantly contain saturated fatty acids and olive oil for example contains mainly unsaturated fatty acids.

The polyunsaturated omega – 6 and omega – 3 fatty acids are building blocks for the so-called prostaglandins. The prostaglandins play an important role for inflammation in the human body. The omega-3’s are building blocks for anti-inflammatory prostaglandins and the omega-6’s are building block for inflammatory ones. Both these fatty acids therefore play an important role. However, it has been suggested that the overabundance of omega-6 in the western diet compared to omega-3 may be undesirable.

Some studies indicate that consumption of saturated fats may increase blood levels of LDL – cholesterol (the bad cholesterol).  There is an association between blood levels of LDL- cholesterol and the risk of cardiovascular disease. Some studies have indicated that replacing saturated fatty acids with polyunsaturated may decrease the risk of heart disease. However, there is indeed very weak scientific evidence linking saturated fat with increased risk for cardiovascular disease.

What Is a Low Carbohydrate Diet?

For general health, public health authorities recommend that carbohydrate intake should be 45 – 65 percent of total energy intake. Let’s look at what this means. An adult woman who engages in daily walking activity may need an estimated 2.000 kcal per day. A recommendation that carbohydrate be 45 – 65 percent of total energy implies that 225 to 325 grams of carbohydrates should be consumed daily.

There is no readily available definition of what “low carb” means. In the first stage of the Atkins diet the upper limit of carbohydrate consumption is 20 grams daily. However, in later phases, carbohydrate consumption is increased. I guess that every diet that recommends less than 100 grams of carbohydrates a day will have to be considered a “low carb” diet.

Most low carbohydrate diets recommend increased consumption of fat in order to meet the body’s requirements for energy.

The War of the Diets

The Hundred Years War is thought to be the longest single war in history, it lasted 116 years. It consisted of a series of battles between England and France, beginning in 1337 and ending in 1453. It began when King Edward III of England invaded France, claiming the throne of France for himself. His successors kept the fight going. Shakespeare admirers will know that Henry V defeated the French at the Battle of Agincourt in 1415.  Joan of Arc led the French to several successes in 1429. Paris was finally liberated from English rule in 1436, and the French finally sent the English out of France completely in 1453.

I don´t know whether the War of the Diets will last for more than hundred years or if there will be a Joan of Arc type dietitian or physician that will come to the rescue, only time will tell. However, I guess that a scientific or a theoretical war may actually have some positives. It certainly provokes lively debates and it may actually stimulate scientific research. The downside is that if you have already chosen a side, you run the risk of neglecting, or not choosing to accept scientific results or arguments that don´t support your own opinion. This may cause argumentation that should be based on scientific data and reasoning to take on the form of propaganda. Unfortunately, we see this happening all the time.

Maybe carbohydrates are not bad as such and maybe fat is not bad either. It may indeed be that when you put those two together that problems start to occur. Maybe moderation is the key as so often is the case.

Some of the “low carb” spokesmen have made the headlines recently. The work and writings of Gary Taubes, Robert H. Lustig, Jonny Bowden, Jeff S. Volek, Stephen D Phinney and Andreas Eenfeldt has surely helped us to better understand the mechanism behind obesity and the metabolic syndrome. It has certainly opened our eyes to the fact that fat is not a problem in our diet today. However, the low-carb supporters have to be careful. If their argumentation is not based on real science and takes the form of propaganda, the cause will be damaged.

Recently a retired thoracic surgeon made the international news headlines by “speaking out on the real cause of heart disease”. This media coverage did certainly not help the low-carb cause although it was meant to do so. Recently I wrote an article explaining why I did not like the surgeons opinionated, nonscientific approach to this important issue.

Recently the UCSF introduced a very interesting video series called “The Skinny on Obesity” where Dr. Robert H. Lustig plays a key role. Keep in mind that if Dr. Lustig is a soldier participating in the War of the Diets, this could be a propaganda film. But, I like it anyway and I think everybody should watch it.  Dr. Lustig is on a crusade against the junk food industry and he has my full support. The videos are professional, informative and fun to watch. I look forward to see more episodes.

A few final words on the war of the diets. Low carb or low fat. Who will prevail?. I am a clinician. I am not going to choose sides in the War of the Diets. I don’t have to. I will take what is best from both sides. I will use scientific data to guide my way to choose what is best for my patients. But, I guess I am allowed to some opinion. Here it is:

  • I doubt that generalized diet recommendations can be given that apply to everybody
  • Over consumption of fat is a rare problem nowadays
  • Saturated fatty acids are not dangerous for our health
  • If your primary target is lowering blood levels of LDL cholesterol (the bad cholesterol) you may benefit from reducing the consumption of saturated fat
  • Mono – and polyunsaturated fats may be a healthier food choice than saturated fats
  • Over consumption of simple refined sugars may contribute to obesity
  • People who are overweight or obese may not tolerate carbohydrates as well as those who are normal weight
  • Individuals who are overweight or obese are likely to lose weight and improve their metabolic function and well being by reducing carbohydrate consumption and eat more fat
  • Not all carbohydrates are bad
  • Choose complex carbohydrates rich in fiber
  • Avoid simple refined sugars
  • If you are an athlete or exercise a lot, the use of simple carbohydrates can be warranted to provide you with easy access fuel
  • People are different and have different metabolic function. Therefore dietary recommendations should be tailored according to the individual needs.

 

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