About low carb and low GI diets

It is important that anyone with a medical condition or who is pregnant should consult their doctor before starting a low carb or low GI diet (for instance, diabetics may find it reduces or even eliminates their need for insulin).

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Why low carb?

Many people who have had little success in controlling their weight with low calorie, very low calorie and low fat diets have discovered that restricting carbohydrate is a far more effective method of both losing excess weight and keeping it off. They also report additional advantages: they eat more, the food they are allowed is more palatable, and they no longer suffer the hunger pangs, lack of energy, weakness, headaches, cravings and feelings of control and deprivation frequently experienced with calorie/fat restriction. A further plus with low carb diets is that there is generally no need to weigh foods or restrict portion sizes.

Is low carb the new 'healthy eating'?

Low carb diets have been around for many decades but their popularity declined in the 70s, 80s and 90s due mainly to unsubstantiated concerns about their safety. However, research since then has shown these concerns to be scientifically groundless. In fact, better understanding of the science behind low carb diets and the link between high carbohydrate intake and obesity, heart disease and diabetes has led many researchers to believe that low carbing is actually more healthy than the low fat/high carb diet we are all currently advised to follow. An article which appeared in The New York Times on 7 July 2002 by journalist Gary Taubes, 'What if It's All Been a Big Fat Lie?' gives an excellent insight into this fascinating subject.

Since then Gary Taubes has published a book called 'Good Calories, Bad Calories: Challenging the Conventional Wisdom on Diet, Weight Control and Disease' (called 'The Diet Delusion' in the UK) providing detailed scientific evidence demonstrating that weight loss is not simply a matter of eating fewer calories, that heart disease is not simply a matter of eating too much fat and that obesity, heart disease and diabetes are instead caused by the insulin-triggering high carbohydrate diet that has become our standard diet.

In similar vein, Dr John Briffa has written various books including 'Escape the Diet Trap', Zoe Harcombe has written 'The Obesity Epidemic - What Caused it? How Can We Stop It?' and countless others have published their own books on this theme of how the traditional weight loss advice of a low fat/low calorie diet and more exercise ignores the reality of how our bodies work and how concerns about low carb diets causing heart disease are not supported by the science.

Low carb diets are not however just about reducing carbs. The Atkins Diet in particular teaches the benefits of plenty of salads and vegetables, fruits if you can tolerate their sugar content and other unprocessed wholefoods such as pulses or legumes (peas, beans and lentils) and wholegrains. It also warns of the havoc that the hormones and other chemical additives and residues that we increasingly find in our food can play with our metabolic processes. Genuine low carb diets are not fad diets or quick weight-loss diets - they are a nutritionally and hormonally based way of eating which promotes improved health, prevents and treats diabetes, improves heart disease risk factors and produces weight loss in the up to 60 per cent of the population who are carbohydrate-sensitive.

Low carb high fat (LCHF) diets

Low carb dieters increasingly call their diet "low carb high fat" or "LCHF" for short. Low carb diets were always relatively high in fat but some people mistakenly tried to do a low fat (and therefore very high protein) version of it. Not realising that in the absence of carbs, the body will make glucose out of protein too, they were unwittingly defeating the low glucose/low insulin purpose of their low carb diet. Dieters starting calling the proper high fat version of the diet "LCHF" to emphasise this aspect of the diet.

Low carb diet trials

Diet trials have shown that, contrary to popular belief, low carb diets (and LCHF diets) are very effective and safe. These trials have also shown unexpectedly good improvement of risk factors for heart disease such as triglycerides, cholesterol and blood pressure. The consistency of these recent findings is causing more and more experts to question their long-held beliefs that to be healthy a diet must be low in fat. Here are some of the studies:

Low carb diets are better for weight loss than low fat diets

'The low-carbohydrate diet was more effective for weight loss and cardiovascular risk factor reduction than the low-fat diet.'

Bazzano, L.A., et al., 'Effects of Low-Carbohydrate and Low-Fat Diets: A Randomized Trial', Ann Intern Med., 2014; 161(5):309-318; DOI: 10.7326/M14-0180

Low carb diets are safe for the heart

'The low carb diet was shown to have favourable effects on body weight and major cardiovascular risk factors.'

Santos, F.L., et al. 'Systematic review and meta-analysis of clinical trials of the effects of low carbohydrate diets on cardiovascular risk factors', Obesity Reviews, 2012; DOI: 10.1111/j.1467-789X.2012.01021.x

Low carb diets are better for diabetes

'Low carbohydrate diets should be the first point of attack in managing Type 1 and Type 2 diabetes.'

Feinman, R.D., et. al., 'Dietary Carbohydrate restriction as the first approach in diabetes management.', Nutrition 2014 ; DOI: 10.1016/j.nut.2014.06.011

Low carb diets do not cause bone loss

'Although the patients on the low-carbohydrate diet did lose significantly more weight than the controls did, the diet did not increase bone turnover markers compared with controls at any time point. Further, there was no significant change in the bone turnover ratio compared with controls.'

Carter, J.D., Vasey, F.B., Valeriano, J., 'The effect of a low-carbohydrate diet on bone turnover', Osteoporosis International, 2006, Vol 17, Number 9, 1398-1403

High protein diets do not damage the kidneys

'Evidence suggests that protein-induced changes in renal function are likely a normal adaptative mechanism well within the functional limits of a healthy kidney. At present, there is not sufficient proof to warrant public health directives aimed at restricting dietary protein intake in healthy adults for the purpose of preserving renal function.'

Martin, W.F., Armstrong, L.E., Rodriguez, N.R., 'Dietary protein intake and renal function', Nutrition & Metabolism, 2005, 2:25

Ketosis is not dangerous

'This study shows the beneficial effects of ketogenic diet following its long term administration in obese subjects with a high level of total cholesterol. Moreover, this study demonstrates that low carbohydrate diet is safe to use for a longer period of time in obese subjects with a high total cholesterol level and those with normocholesterolemia.'

Dashti, H.M., Al-Zaid, N.S., Mathew, T.C., Al-Mousawi, M., Talib, H., Asfar, S.K., Behbahani, A.I., 'Long term effects of ketogenic diet in obese subjects with high cholesterol level', Mol Cell Biochem, 2006, 286(1-2)1-9

Low carb diets are helpful for PCOS

'In this pilot study, a Low Carb Ketogenic Diet led to significant improvement in weight, percent free testosterone, LH/FSH ratio, and fasting insulin in women with obesity and PCOS over a 24 week period.'

John C Mavropoulos, J.C., Yancy, W.S., Hepburn, J., Westman, E.C., 'The effects of a low-carbohydrate, ketogenic diet on the polycystic ovary syndrome: A pilot study', Nutrition & Metabolism, 2005, 2:35

Low carb diets - their place in healthy eating advice

'We emphasize that strategies based on carbohydrate restriction have continued to fulfill their promise in relation to weight loss and that, contrary to early concerns, they have a generally beneficial effect on most markers of CVD, even in the absence of weight loss. In combination with the intuitive and established efficacy in relation to glycemic control in diabetics, some form of LCD may be the preferred choice for weight reduction as well as for general health.'

Westman, E.C., Feinman, R.D., Mavropoulos, J.C., Vernon, M.C., Volek, J.S., Wortman, J.A., Yancy, W.S., Phinney, S.D; 'Low-carbohydrate nutrition and metabolism', American Journal of Clinical Nutrition, 2007 August; Vol. 86, No. 2, 276-284.

The Atkins Diet for epilepsy

'A modified Atkins Diet is an effective and well-tolerated therapy for intractable pediatric epilepsy.'

Kossoff, E.H., McGrogan, J.R., Bluml, R.M., Pillas, D.J., Ruberstein, J.E., Vining, E.P., 'A modified Atkins Diet is an effective and well-tolerated therapy for intractable pediatric epilepsy', Epilepsia, 2006, 47(2):421-424.

Pro-low carb medical professionals

The increasing weight of evidence supporting low carb diets has caused many medical professionals to rethink their previously negative stance. In the UK, General Practitioners Dr Sarah Brewer and Dr John Briffa were early advocates of low carb diets. Many other GPs and hospital doctors have followed them since. Other notable UK low carb medical advocates in the public eye include:

In the USA, practising doctors using low carb diets with their patients include:

In Canada, low carb-friendly doctors include:

In Sweden the "LCHF diet" (as low carb diets are generally referred to in Sweden) has become much more accepted as 'healthy eating' by mainstream medicine than has yet been the case in other countries. Whether or not this acceptance accounts for the extraordinary success of the Swedish low carb high fat website 'DietDoctor.com' or indeed, whether the DietDoctor.com website itself has been the driver in popularising the LCHF way of eating, the obesity epidemic in Sweden seems to have significantly abated. After decades of skyrocketing obesity all around the world, with obesity rates in the US for instance already past 38 percent and going up fast, the obesity percentage in Sweden suddenly stabilised at 14 per cent, just when LCHF became widely popular. A coincidence? Not according to ...

The science behind low carb diets

Low carb diets are based largely on the science of blood sugar control mechanisms. A very simplified explanation of the process is as follows: carbohydrate foods (starches and sugars) are converted by digestion to a form of sugar called glucose. The rising levels in the blood trigger the pancreas to release the hormone insulin. It is the job of insulin to keep the blood sugar levels stable and trigger the process by which excess glucose is removed from the bloodstream and, if not needed for immediate energy, stored as fat.

This storage mechanism was extremely useful in mankind's hunter-gatherer days. It enabled early man to survive in between his irregular and unpredictable meals. Unfortunately, this storage mechanism is not so useful where food, and carbohydrate in particular, is constantly in abundance. Our bodies were not designed to be fuelled by the highly refined carbohydrate-dense foods such as white sugar and flour that are now the staple foods of the Western world. In time the process of evolution might result in a population genetically adapted to such a diet, but this would take millions of years, not the tens of years that such foods have been available to us in the quantities in which we consume them today.

The trick is to stop this constant production of insulin. Low carb diets attempt to do this by avoiding glucose surges ('spikes') in the blood. This can be achieved by restricting carbohydrate overall, and by preferring those carbohydrates which rank low on the glycemic scale (ie which cause less rapid rises in blood sugar).

The Atkins Diet is probably the most well known and widely used low or controlled carb diet, but other examples include Dr Richard Mackarness' Eat Fat and Grow Slim Diet, Protein Power, The Paleolithic Diet, the Stone Age Diet, the South Beach Diet and the Dukan Diet. Although many of these diets have appeared relatively recently, the Atkins Diet dates back to the seventies and Dr Mackarness' back to the fifties. However, the first true low carb diet was around long before that - the Banting Diet. Used by William Banting in 1862 to lose 50lb in less than a year, he was so delighted to have found a way to solve his weight problem that he published a pamphlet "Letter on Corpulence" in 1864 at his own expense. Other diets that have become popular recently involve fasting for defined periods of time (examples include Dr Michael Mosley's '5:2 Fast Diet' - these also generally incorporate a low carb approach.)

By cutting carbohydrate intake to an extremely low level, the body can be made to 'change gear' and burn fat for energy 100 per cent of the time. Low carb diets which aim for this are referred to as 'ketogenic'. However, the change of gear will only happen once the body has used up its other, more readily available energy stores. One way of telling whether this has happened is to test for ketones, which are excreted as a harmless byproduct of this fat breakdown. This is called being 'in ketosis'. (Ketosis is commonly confused with, but has nothing to do with ketoacidosis, which is a serious complication of uncontrolled diabetes.) Testing for ketones can be done quite simply by using urine test strips. Of the numerous variations of low carb diets around today, some are ketogenic and some not. Of the ketogenic type, the Atkins Diet is probably the best known and most widely used.

The link between high carbohydrate intake and obesity, heart disease and diabetes

At best, constantly high insulin levels may make it difficult for the individual to lose or maintain weight. However, if the overproduction of insulin is allowed to continue, insulin resistance may develop, more and more needs to be produced to get the same effect, and ultimately the stressed pancreas may cease to produce enough insulin or give up altogether, producing full-blown diabetes. Not only that, but there is a growing body of evidence to support the belief that it is these constantly high levels of circulating insulin (and not dietary or blood levels of fat) that are the real culprits in creating the damage that results in cardiovascular disease, whether or not diabetes is present.

In other words, many believe that the real villain in obesity, heart disease and Type 2 diabetes may be high dietary intake of carbohydrate, not fat. If this is the case, then it means that for many of us, following the current official 'healthy eating' guidelines may be entirely the wrong way for us to be eating. Swedish Diet Doctor Andreas Eenefeldt's article 'How to Reverse Type 2 Diabetes' is an excellent place to learn more.

Syndrome X / metabolic syndrome, PCOS and acne

A low or controlled carbohydrate way of eating is also increasingly being seen as beneficial in a number of other insulin-related conditions, whether or not weight loss is the primary aim, which include Syndrome X (also called insulin resistance or Metabolic Syndrome) and PCOS (Polycystic Ovary Syndrome). Teenage acne is also now believed to be related to insulin levels by some dermatologists, who advocate a low carb diet as treatment.

Food allergy / food intolerance and candida

Low carb and low GI diets can also help where food allergies / food intolerances and candida (yeast overgrowth in the gut) are a factor in ill health. These conditions are increasingly considered by nutritional medicine practitioners to play an important role in inability to lose weight and other chronic problems ranging from headaches and indigestion to arthritis and irritable bowel syndrome. The literature demonstrates the largely unrecognised prevalence of these conditions and explains how they can be caused or fuelled by over-consumption of refined carbohydrates, leading amongst other effects to blood sugar/insulin imbalance and obesity.

Dr Atkins and many other low carb diet authors acknowledge the existence of food intolerance / allergy and candida. They suggest they may be a reason why so many low carb dieters not only achieve weight loss but also find other health problems have improved or disappeared. Future research may confirm that these conditions are closely linked with the blood sugar / insulin regulation that is the underlying premise of low carb diets. What is for sure is that many low carb diets restrict or eliminate the foods, such as wheat and corn (maize), that are most often implicated in these problems. This and many other reasons for difficulty in losing weight are explained in "Why Can't I Lose Weight".


A very strict version of ketogenic diet has been used for many years in childhood epilepsy that failed to respond to anti-epileptic drugs. Although the mechanisms are not fully understood, the ketogenesis alters the metabolism of the brain in a way that can reduce the risk of seizures. However, this treatment for epilepsy fell out of favour over the years due to difficulty in keeping to the diet and concerns about cholesterol levels.

The concerns about cholesterol levels were shown to be groundless, and moreover, some epilepsy specialists, Dr Eric Kossoff at John Hopkins in particular, discovered that less strict versions of the ketogenic diet, such as the Atkins Diet or a modified version of it, can be just as effective. Furthermore, the explosion in popularity of low carb diets for weight loss purposes has enormously improved the availability of low carbohydrate food substitutes, cookbooks and restaurant menus, which make following a ketogenic or low carb epilepsy diet much easier. In his 2016 presentation "Dietary Therapy for Epilepsy: Current Status and Future Directions" Dr Kossoff explains how ketogenic or low carb diets have become almost mainstream for epilepsy in many parts of the world.

The low carb recipes in the Low Carb Cookbook are particularly suitable for those following the Atkins Diet or a modified form of the Atkins Diet for seizures as they are extremely low in carbohydrates and fit well into the allowance of 10 to 20 grams of carbohydrate per day that are often recommended for epileptics using the diet. Good results have also been obtained by starting the diet with a low level of carbs which is then increased after a period of time. The interactive features of the Low Carb Cookbook are particularly useful as the carbohydrate values of individual ingredients are shown, and ingredients can be adjusted and carb counts automatically recalculated, according to the changing needs of the person using the diet. Recipes can also be added, and imported from other sources.

Low carb vs low calorie diets

About the single worst thing you can do for long term weight loss is to restrict calories excessively. While very low calorie diets do take off weight quickly (which is what most people want), the long term results can be disastrous. The reason is that a severe reduction in calories (say to below 1200 a day) can make the body go into starvation mode, slowing metabolic rate. Once calories get below a certain point, even serious exercise will not prevent this slowing. And once you start eating again (as you can't starve yourself for ever), the lowered metabolic rate will cause you to gain weight even more easily than before. Additionally, significant calorie reduction triggers changes in fat storing enzymes, making them more active. Low carb diets maintain calories at a high enough level to avoid this happening. This is explained more fully in "Why Can't I Lose Weight - The real reasons diets fail and what to do about it".

For many people, the effect of carbohydrates on their blood sugar levels is very much like an addictive drug, causing cravings which make dieting or even just controlling their eating effectively doomed from the start. Calorie-restricted diets do not address this problem, and may even aggravate it, if they emphasise intake of carbohydrates. Carbohydrate cravings usually disappear completely once past the initial few days of a low carb diet.

Low carb diets are not crash or fad diets. They are based on the scientifically proven fact that some people (possibly the majority of the population) are metabolically unable to handle large amounts of carbohydrate. The best low carb diets allow the dieter, once the excess weight has been lost, to find their individual level of tolerance for carbohydrates and to get used to the new way of eating. They also gradually guide the dieter to the realisation that going back to the old way of eating will not only put the weight back on but will also expose them to the other health risks that having this type of metabolism is increasingly being shown to involve.

Advances in knowledge since the early days of low carb diets have also shown that the carbohydrate restriction does not need to be as severe as was previously thought necessary to be effective. The new palatability and variety this has afforded low carb diets has made them enjoyable enough for long term use, ie for maintenance once the excess weight is lost. To illustrate the point, low carbers more often refer to their 'way of eating' than their 'diet'. This acceptability as a permanent way of eating is a significant advantage, as keeping the weight off in the long term is important and it is widely acknowledged that low calorie and low fat diets have failed dismally to deliver in this respect.

Low GI and low GL diets

GI stands for glycemic index, which is a way of measuring the rise in blood glucose (or 'blood sugar') after eating carbohydrate foods. Low GI diets are based on the same principle as low carb diets, namely that eating too much of the kind of food that makes your blood sugar rise fast and high (which then triggers high levels of insulin) is an important cause of overweight. The most well-known examples of low GI diets today are probably The GI Diet by Rick Gallop and the South Beach Diet by Dr A Agatston, but the concept of the glycemic index itself was invented by David Jenkins and Thomas Wolever of the University of Toronto in the 1970s/80s, and the earliest low GI diet, the Montignac method, dates back to the 1980s.

Although the 'rules' may look different, the foods eaten on a low GI diet are very similar to those eaten on a low or controlled carb diet. Both approaches involve the avoidance of the highly refined white flour, sugar and other processed grains that have become our staple foods today. Both approaches encourage lots of healthy salads and vegetables (although the Atkins Diet in particular is often misquoted as not allowing vegetables and fruits).

Whereas low carb dieters count carbs, low GI dieters choose their carbohydrate foods based solely on their GI ranking. This can produce distorted results. For instance, if relying on the GI alone, a GI dieter may be put off eating carrots because they are surprisingly high on the glycemic scale. For this reason, the concept of glycemic load (or GL) was invented, which involves multiplying the GI of the food by the carb content of the amount to be consumed. This gives a more meaningful picture of what the overall effect will be of eating that particular portion of food. In the case of carrots, it demonstrates that carrots are still a good choice for GI dieters (although not perhaps low enough in carbs for most low carb dieters).

Low GI diets generally include starchy vegetables (potatoes, parsnips, carrots etc), fruits, pulses and wholegrains from the outset, wherease many low carb diets prohibit these 'good' carbs in their initial phase, then gradually add them back according to the individual's ability to tolerate them. (Unfortunately some people do not have a very high carb tolerance - which is why low GI diets may not be restrictive enough for such people to lose weight on them. By the same token, some low carb plans are not low enough in carbs for some people either.)

Both low GI and low carb diets are concerned to a certain degree with fats. However, low GI diets tend to promote the avoidance of fat, saturated fat in particular, whilst low carb diets, and most notably, the Atkins Diet, do not. (What is not often recognised is that the Atkins and other low carb diets have always paid attention to fat - but they distinguish between 'good' and 'bad fats'. For instance, olive oil and fish oils and certain saturated fats are 'good' fats, while trans fats (hydrogenated oils) are 'bad' fats. Unfortunately, saturated fat got the blame for the wrongdoings of trans fats years ago, before it was recognised that there was more than just one type of saturated fat. This fact is now becoming more widely recognised.)

A low carb diet is more restrictive than a low GI (or low GL) diet, but everything allowed on a low carb diet is generally permitted on a low GI Diet (because foods that are low in carbs cannot have much of a glycemic effect). So the low GI dieter can for instance use recipes developed originally with low carbers in mind, such as those in the Low Carb is Easy Cookbook.

Further resources and references