Diet in insulin resistance.

 Whilst I see my role as a clinician is to establish the diagnosis of insulin resistance and explain the pathophysiology of this to the patient, I make the following suggestions. But for implementation of these diets, the individual needs the help of a dietitian who understands and agrees with the basic concept of an insulin aware diet.

At the outset it should be appreciated that insulin resistance occurs both in the overweight, those with normal weight and the underweight.

The factors which lead to insulin resistance of course being hereditary and lifestyle. The latter include exercise and stress, age and concurrent medication, infection and trauma. All of those factors are important but the one most neglected and misunderstood is diet.

Concerning diet books. There are many of these now available and are referred to as "insulin aware diet books". Whilst each of these books takes a different approach they all have much to offer in understanding the pathophysiology of insulin resistance. A list of these books will later be attached as a reading list. The underlying theme of all of these books however is an understanding of those foods which over-stimulate the production of insulin. This over-production is referred to as "hyperinsulinaemia".

Consequently when looking at a new book on diet, always check the index for the words "hyperinsulinaemia", "impaired glucose tolerance" and "insulin resistance".

In a discussion of diet it is important to recognise two completely different groups of compounds; the first are the micronutrients - the vitamins, minerals, essential fatty acids, essential amino acids and the like; the second are the macronutrients - the proteins, carbohydrates, fats & oils. On one hand attention to the correct balance of

"macronutrients" has been neglected.

On the one hand vitamin, mineral and nutrient supplements come from the health shop and there has always been a lot of information in relation to this. On the other hand the macronutrients come from the butcher, the baker, the greengrocer and the supermarket and we all - doctors and the community alike - have been given a barrage of conflicting advice. But certain basic principles are now emerging. Firstly it is important of course to have an adequate intake of vitamins, minerals and the essential amino acids and fatty acids but this is grossly inadequate unless there is a correct balance of macronutrients. The macronutrients of course being carbohydrates - which should be complex; protein which should be lean and fat free and vegetable, plant and animal oils and fats. So far so good and there is general agreement on all that I have said.

However it is the implementation of the correct balance of macronutrients that causes confusion and controversy.

My clinical experience would suggest that in the younger individual where insulin resistance is predominantly receptor type insulin resistance which is switched on or off during and after puberty; during and after the luteal phase of the menstrual cycle in women; during and after pregnancy; during and after both acute and chronic stress at all ages whether due to trauma, infection or traumatic emotional events - in all of these situations insulin resistance is increased during the event and should revert to normal after the event.

Much more research needs to be done on the reasons why insulin resistance fails to revert to normal in some individuals and not others but certainly dietary and lifestyle factors predispose to continuance of increased insulin resistance.

As discussed elsewhere, it must be understood that hyperinsulinaemia and insulin resistance are normal physiological responses in the body-

- just as elevation of the body temperature and elevation of the pulse are physiological events in response to infection. These individuals then with the primary receptor type insulin resistance usually respond to the Insulin Aware Diet without going into Dietary Ketosis which will be discussed below. In the insulin aware diet a balance of macronutrients is recommended; as a start the recommendations of Barry Sears in his book "Enter the Zone" is a good concept to embrace - namely the "40/30/30" diet - "40% complex carbohydrate; 30% fats and oils; 30% lean protein". Whilst most men and women before middle age will respond to the Insulin Aware Diet, some, particularly those whose diet history reveals a longstanding dietary imbalance, require the carbohydrate levels to be lowered. Dietary ketosis may not be achieved in these individuals however.

Dietary ketosis is the second level of dietary manipulation to achieve control of insulin resistance.

To understand this dietary procedure, it is suggested that you read the chapter "Doctor to Doctor" in the book by Ezrin and Kowalski. Dietary ketosis alone does not achieve weight reduction unless there is concurrent reduction of the total calorie intake. It is possible in fact to gain weight when in dietary ketosis if there is a high intake of calories. However dietary ketosis avoids over-stimulation of insulin production and as insulin has been called the "hunger hormone", it is then possible to limit the calorie intake. The concept of dietary ketosis is the basis of the very low calorie diet "Modifast". The recommended guide to achieving dietary ketosis is to measure the presence of ketones in the urine with Ketostix or Keto-Diastix.

However there are some individuals who despite strictly following the Modifast diet or the Ezrin/Kowalski diet, fail to excrete ketones in the urine. This problem has not been adequately addressed; it may simply reflect the extreme efficiency of some to prevent loss of ketones in the urine. But a common mistake is not to appreciate the very small amount of food necessary in this diet. To help to understand this concept further, it should be understood that when on a normal diet, glucose is metabolised in the cells to carbon dioxide and water, the carbon dioxide being blown off through the lungs. However in dietary ketosis, whilst the brain continues to require glucose, the muscles switch to burning fat with the production of ketones. These ketones may be recycled in the liver but may also be excreted in the urine. In this context it should be appreciated that in the individual on a normal diet in aerobic exercise, there is sufficient oxygen to ensure that glucose and glycogen (muscle sugar) is burnt to carbon dioxide and water. However in anaerobic exercise or where the rate of combustion of glucose and glycogen exceeds the rate of supply of oxygen to the muscle, then anaerobic metabolism provides the energy with the build up of lactate in the muscles; this build up of lactate is responsible for the sore muscles following exercise. If this sounds complicated, let's face it, it is! The above is only a very brief outline of the provision of energy when our body burns its fuel. Put simply, glucose (blood sugar) or muscle sugar (glycogen) plus oxygen releases energy plus carbon dioxide plus water. Alternatively fats plus oxygen produce energy plus ketones. The removal of the waste products, carbon dioxide and ketones is achieved by the lungs and kidney respectively.

In conclusion then it would appear that most individuals will overcome insulin resistance by following an insulin aware diet (see below) providing they exercise and are successful in losing weight. Some however with longstanding insulin resistance may need to follow the dietary concept of dietary ketosis. Finally, whatever diet is followed, the dangers of fasting should be fully understood.

Click here to see my thoughts on fasting.

Click here to look at the Dietitians Insulin Aware diet

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