211. The Case Against a Low Carb High Fat (LCHF) Diet.

Those who follow this blog will be well aware that there is overwhelming evidence that there are very significant benefits to personal health by having a habitual diet which is LCHF. This has been demonstrated by many different research studies and is confirmed by hundreds, if not thousands, of personal case histories. All of this is now underpinned by sound theoretical logic which identifies the critical role played by insulin resistance in the development of a range of common chronic diseases.

Opposition to LCHF

Nevertheless there are many individuals and organisations which are not persuaded by the force of the arguments and go to considerable effort to discredit this evidence. I have just been alerted to one example, which is a presentation (1) by Dr Pamela Dyson of the Oxford Centre for Diabetes, Endocrinology & Metabolism (OCDEM) which is located at the Radcliffe Department of Medicine, University of Oxford. The title is:

“High fat, low carbohydrate diets as the first approach in managing type 2 diabetes: Against”

At the outset it is disclosed that Pamela Dyson has received honoraria for lectures from pharmaceutical companies including Lilly, MSD, Novo Nordisk and Sanofi, and unrestricted grants from Abbot Laboratories, the Sugar Bureau, the PepsiCo Foundation and Novo Nordisk.

Current official advice

It is accepted that since the 1980s, diets low in saturated fat (SFA) and high in carbohydrates have been recommended in order to reduce the risk of CVD and CHD. Those with Type 2 Diabetes (T2D) should have a diet which is low in SFA. However it is recognised that the roles of SFA and carbohydrates in the management of T2D is being questioned.

Justification for the advice

With respect to the use of a diet which is low in carbohydrates and high in fat (LCHF) as a form of treatment for T2D the position is summed up by a quote:

“To recommend a low carbohydrate, high saturated fat diet in people with type 2 diabetes would be to advocate for a dietary approach that is not backed by current studies”

However the source of this is an article (2) published in Diabetic Medicine which is published by Diabetes UK entitled:

“A critical review of low-carbohydrate diets in people with Type 2 diabetes”

This review is based on 12 different studies. Essentially what we have is mish-mash of different types of studies. In 5 of these studies there are no baseline data and it was not possible to determine the reduction in carbohydrate intake that was achieved. In most of the others the reduction in the intake of carbohydrates was comparatively small so these results would not have been able to provide any useful information on the impact of a low carbohydrate diet. Some were high fat and some were low fat. Some were calorie- controlled and others were not.

Sorting out the wheat from the chaff

In effect 2 separate issues are conflated in this review. On the one hand it is argued that many of the studies did not succeed in reducing the carbohydrate intake substantially and so it is concluded that this approach is not feasible. On the other hand, where there is a big reduction carbohydrates consumed it is argued that there was no significant improvement in T2D. In fact there is only one study which achieved a big reduction in carbohydrate intake and this is that done by Eric Westman and colleagues (3). This reduction was 196 gm, which is much greater than anything achieved in any of the other studies. Perhaps it is significant that this was the only diet which found that that there was a reduction in body weight. The review did accept that the weight loss could not be explained by calorie reduction and that a possible cause was that less insulin would be produced on a diet which is low in carbohydrates.

The crux of the issue

This is almost certainly the key to the widespread success of low carbohydrates in the treatment of T2D as demonstrated by research and by countless diabetics who have discovered for themselves, the beneficial effects of such diets. Incidentally it is also crucial to point out that one of the important results of the Westman study is that there was a dramatic reduction in the use of drugs and several individuals were able to stop using insulin completely. Unfortunately the review failed to mention this.

To any reasonable person one of the best ways to assess any type of treatment must be the amount of drugs that are being used. If this can be lowered then that is very good evidence of the effectiveness of the therapy. Therefore it is highly relevant that other studies which have provided confirmation of this result have not been mentioned in the review. Here are two examples..

A useful contribution to our understanding has been provided by a recent study conducted in Australia under the auspices of the Commonwealth Scientific and Industrial Research Organisation (CSIRO) (4). This investigation was specifically aimed at those with T2D who were overweight or obese. The participants were divided into 2 matched groups. One of these was allocated to a diet containing 14% energy (<50 g/day) of carbohydrates (Low carb, LC) and other had a diet with 53% energy as carbohydrates (High carb, HC). All participants were required to undertake vigorous exercise under supervision on 3 occasions every week. The calorie intake in both groups was similar and the study continued for a full calendar year.

Both groups lost weight and also achieved similar reductions in the HbA1c (the % glucose attached to the haemoglobin which gives a good estimate of the blood glucose over the past 3 months) However in other respects the LC group was superior. In particular, it was found that there was less variation in the blood glucose levels over a 24-hour period, which meant that there were significant reductions in medication needed for glycaemic control. This is highly important because this would equate to considerable savings in the costs of treatment coupled with less likelihood of drug-related side effects. These include hypoglycaemia, which is what happens if a drug reduces the blood glucose to levels which are too low, so that the patient loses consciousness.

In another paper written by members of the same research team it was noted that the total economic costs of T2D have been estimated as A$10.3 billion in Australia and US$174 billion in the USA (5). Referring to the results of the study described here, they comment:

“its most striking benefit is that it reduces the amount of medication someone with diabetes has to take by half. This reduction was three times greater than for people who followed the lifestyle program that incorporates a traditional high-carbohydrate diet plan”.

The outstanding work of Dr David Unwin

In Southport which is not far from Liverpool, Dr David Unwin and colleagues have successfully treated diabetics with a diet which is low in carbohydrates in their General Practice (6). In a study with over 60 people the average weight loss was 9kg, the blood sugars were normalised and most impressive of all, the fat in the liver was reduced substantially.

The case history of one patient is particularly impressive.

This was a 55-year old woman who started out with an HbA1c of 84 mmol/mol (9.8%) which is effectively out of control and a gamma-glutamyl transferase (GGT) of 103 iu/L which showed that the liver function was deranged. Essentially this is a bad case of T2D. She had been prescribed metformin. After 3 months on the LC diet the GGT was down to 12 iu/L (a reduction of almost 90 %!!) and an ultrasound scan confirmed the liver was functioning normally. She also lost 7.9 kg. In the longer term she has lost a bit more weight, the liver function is fine, her HbA1c is just about OK but she has come off the metformin. She has lost 17 cm from her waist and says she feels “10 years younger”.

(Note HbA1c is a measure of blood sugar and GGT is a marker for Non Alcoholic Fatty Liver Disease).

To cap it all, this practice has reduced its expenditure on drugs by at least £30,000 per annum.

Conclusion

We have now reached a point where there is overwhelming evidence that a diet which is low in carbohydrates is a very effective treatment for T2D. Reports that that it does not work are invariably dependent on careful selection of the data and the aspects to be considered. Even without detailed investigations, our existing knowledge of the disease and how it develops inevitably points to excessive intake of the foods which result in raised blood glucose levels as I have explained in a my blog entitled “A FLOOD OF SUGAR” (7). It is therefore no great surprise that those who are skeptical about the benefits of a low carb diet have close links with the drug industry. Surely they are not influenced by the fact that widespread adoption of treating T2D by altering the diet would result in a massive reduction in the sales of drugs such as insulin?

References