Carbohydrate wars

We know sugar is Bad. 

but, what about eating complex carbohydrates such as rice, sweet potatoes and brown bread- surely they are good?

Today, as we deal with widening waistlines and a rise in type 2 diabetes and other inflammatory diseases, scientists and journalists are asking the question: "Does our diet, rather than lack of exercise, hold the answer?."   

You may be thinking that we're all just eating more than ever before, with no food shortages or periods of fasting, and that what we eat has changed: more sugar, processed foods and oils.

So let’s see what history and science tells us.

For the last 10 years a new way of eating started to become popular- the ‘High fat, moderate protein, low carbohydrate’ movement.  

This concept.  In many cultures across the world, from Africa to the Artic, indigenous people have been eating foods high in saturated animal fat and very low in carbohydrate for centuries, without ill effect.  But, 10,000 years ago, this eating habit changed with the introduction of modern agriculture and the widespread production of wheat, corn, vegetables and fruit. 

Many of you will have read Dr Aitkins 1970’s book on eating a high saturated fat diet of cheese and bacon, while avoiding carbohydrates such as sugar, bread and pasta- even whole grain and pasta.  You may even have heard of the undertaker called Thomas Banting who in the 1800’s was prescribed a similar diet, by a French physician, to loose weight after many failed attempts on other diets.  

A more recent advocate for high fat low carb eating, Prof. Phinney, explains that eating too much carbohydrate is dangerous, eating  65% of your calories as omega- 3 fats can help you loose weight and stay healthy.  

In the field of sports medicine, Prof. Tim Noakes, a marathon runner and physician, who previously advised athletes to load their diet with carbohydrates to improve performance, now follows and prescribes the high fat/low carb diet.

Despite some scientific studies showing the benefits of low carbohydrate( < 30%), high fat (65-80% fat) diets in certain patient groups, there still remains a consensus that carbohydrates, in the form of whole grains, are an essential part of human health and that increased fat, particularly saturated fat, is bad. 

The studies which conclude that 'low' carbohydrate diets are not beneficial and may reduce life expectancy have not used what Prof Phinney considers 'a very low' carbohydrate intake i.e. below 30% of total calories.  He explains that above this level, patients will not be in a state of nutritional ketosis which should produce beneficial affects.

In 2009 I read the China study by Dr Campbell and his father. Although their epidemiological findings came under criticism for reporting association of eating habits with health outcomes, I still 'felt' a diet of mixed vegetables, some wholegrain rice and fruit, no animal products and no sugar, was the optimum way of eating.  I did however add fish to my diet to improve protein and omega 3 intake and continue to eat and cook with olive oil.  

Since the late 1990's I also 'understood' that the only diet to improve ones lifespan was the Mediterranean diet and more importantly, that olive oil was better at lowering bad cholesterol than the drugs we were prescribing. called statins.  

Then came Nina Teicholz’ best selling book 'Big fat lies' and I suddenly began to wonder whether the blame for ill health really lay with saturated animal fats.  Her book explains that the evidence for recommending low saturated fat intake is weak.  

She also found holes in the mediterranean diet studies in relation to living longer, which was a bigger fat surprise!

So who is right?  And what should all of this mean for you and your diet?

Before, considering an extreme Ketogenic diet or even before lowering you carbohydrate intake it’s useful to understand The relationship between weight gain, carbohydrates and insulin.

Insulin is the growth hormone that is normally produced from your pancreas gland, behind your stomach, in response to eating sugar or other carbohydrates-even whole grain carbohydrate like brown bread.  But,If you didn’t produce insulin you would develop very high blood sugars and type-1 Diabetes. 

Insulin essentially mops up sugar, which is toxic in high levels, and helps store it in your body in different energy forms such as glycogen and fat.

If you constantly eat too much sugar or carbohydrate you will eventually produce chronically high insulin levels that remain high even when you are not eating carbohydrates.  And, as Insulin causes the body to store fat, you will lay down adipose (fat) tissue under the skin, in your liver, and over other organs. This will also increase the fat in your blood called triglycerides (part of the cholesterol blood test) and cause narrowing of your blood vessels (called atherosclerosis).

If you continue to eat lots of sugar you also become desensitised (or resistant) to the insulin, meaning you need to produce higher levels of insulin every time you eat carbohydrates. The result is that you lay down even more fat throughout the body and risk developing type 2 diabetes.


This diagram shows the spectrum of carbohydrate tolerance. You may be very intolerant of carbohydrates, so when you eat just 30% of your calories as carbohydrates you produce high levels of insulin. Or on the other end of the spectrum you may be very tolerant of carbohydrates and can eat 60-70% of calories from carbohydrates without producing high levels of insulin. There are also people in between these two extremes.


Can anyone become resistant to insulin and intolerant of carbohydrates ?


  • Having an increased waist circumference through increased food intake or reduced physical activity will mean you need to produce more insulin to deal with the continuous intake of too many calories. 

  • If this process of overeating and no exercise continues your body will continue to produce high levels of insulin.

Inherited insulin resistance

  • Type 2 Diabetes is the best example as most people in the early stages are producing high levels of insulin. But, because the body’s tissue are resistant to actions of insulin, sugar cannot be stored in muscle cells and so remains in the blood.

  • A family history of type 2 Diabetes means that you may have inherited those genes for type 2 diabetes and are therefore as risk of developing insulin resistance if you eat too many carbohydrates and do not exercise.

  • Women who have polycystic ovarian syndrome (PCOS) are 5-10 times more likely to be Glucose (Carbohydrate) Intolerant than other women and therefore at higher risk of insulin resistance.

How do you treat insulin resistance?

  • Decrease carbohydrate intake. Sweet potatoes, brown rice, quinoa or wholegrain bread are the better carbs to eat. The fibre helps with diegstion and also causes a slower absorption of sugar from the stomach.

    But try and get your carbs from vegetables which also contain lots of fibre, vitamins and minerals.

  • Exercise: Type 2 diabetics who exercise regularly can reduce their blood sugars and even ‘reverse’ the disease. One of the first studies to show this was in 2001 in the New England journal of medicine. Men and women who exercised on exercise bikes 5 days a week lowered their high blood glucose level back to normal range.

  • Medications: For type 2 diabetes there are medications which help the cells in the body become more sensitive to insulin, which improves the uptake of sugar.

  • Dr Phinney's research has shown that improved insulin sensitivity can be achieved by reducing the daily carbohydrate intake to below 30% of total calories and replacing these calories with fat such as olive oil, avocados, nuts, seeds and butter. The exact amount of carbohydrate depends on how insulin resistant you are i.e. the more insulin resistant you are the less carbohydrate your body can tolerate.

here’s a link to a large study showing that exercise and diet are better than the standard diabetic medication at lowering blood sugar:

My advice In this world of food on offer everywhere you go:

  • Keep the carbs low by eating lots of lovely vegetables, fill-up on good fats (still controversial) and eat qaulity protein like fish and nuts and seeds.

  • Enjoy sugary foods as treats now and again

  • Fast i.e. don’t eat breakfast! so that you have a 16 hour window without eating, it’s easier than you think.

  • And ofcourse, go for a walk every day or cycle.

We’ll talk about fasting in the next blog and maybe fats and then get to protein and our dilemna of eating animal products that affect climate change.

Happy eating!