NHS expert DR DAVID UNWIN shares his revolutionary plan
How does low carb help type 2 diabetes?
Rather like hybrid cars, our body is designed to burn two fuels — sugar or fat in its case.
Cutting back on sugar and starchy carbohydrates that digest down into sugar means we’re better able to burn fat.
This can help people with obesity, or type 2 diabetes (those who essentially have a problem with sugar) because they then become a ‘fat burner’, helping to get rid of excess belly fat.
A small bowl of boiled rice, for instance, has the same effect on blood sugar as ten teaspoons of table sugar (more on that later). Normally glucose is dealt with by the hormone insulin, which pushes it out of the bloodstream and into your muscles; any excess goes into your belly fat or liver
Some people misunderstand low carb, thinking that it must mean the body gets most of its energy from protein and fat instead.
However, it does get the body burning body fat — hence the average weight loss of nearly a stone and half (9kg) I’ve seen in my patients.
Why can’t you have starchy foods?
Going low carb to tackle type 2 diabetes can mean limiting, or avoiding starchy foods because although they contain valuable nutrients and fibre, starchy carbohydrates — cereals, wholemeal bread, rice, some root vegetables (eg potatoes) and tropical fruits — break down in the body to produce surprisingly high levels of sugar (glucose) in your blood.
A small bowl of boiled rice, for instance, has the same effect on blood sugar as ten teaspoons of table sugar (more on that later).
Normally glucose is dealt with by the hormone insulin, which pushes it out of the bloodstream and into your muscles; any excess goes into your belly fat or liver.
But people with type 2 have a particular problem with dealing with glucose, and sugar builds up in the bloodstream where, over time, it can damage blood vessels in vital organs.
While it’s generally accepted that high-sugar foods are a problem for people with type 2 diabetes, the role played by starchy carbohydrates — also made up of sugar — is sometimes overlooked.
Of course, good carbohydrates remain an important food group for other people, but if you have type 2, this ‘hidden sugar’ in foods can undermine your efforts to control your blood sugar levels.
You can easily get fibre and nutrients provided by these starchy carbs and tropical fruits from other food sources.
What about wholemeal bread?
One of the things that surprises people about a low-carb approach to type 2 is that it can mean avoiding foods such as wholemeal bread and bananas. This is because they can contain surprising amounts of ‘hidden’ sugar.
Foods vary a lot in terms of how much sugar they produce when digested — and this is no less true for carbs.
For example, corn flakes are worse than wholemeal bread — this is seen by where they appear on the glycaemic index (GI), a well-established way of comparing what effect different carbohydrates may have on your blood sugar.
The glycaemic index compares different carbs to pure glucose (which has a score of 100, so the higher the score, the more your blood sugar levels will rise after eating that food).
But this doesn’t tell you the whole story — it doesn’t explain what effect a particular sized portion of food has on your blood sugar. For this we use a more sophisticated measure, the glycaemic load (GL). This is measured in grams of pure glucose.
While this is a very useful tool for people with diabetes — and one recognised by an international panel of experts (including from the Harvard School of Public Health in the U.S.) in 2015, I found that in practice, my patients were unfamiliar with ‘glucose’ as a substance and didn’t use grams. So they struggled to visualise what pure glucose was like and what, say, 16g of it represented.
So I enlisted the help of a leading international expert, Dr Geoffrey Livesey, who was recommended to me by one of the very scientists who helped devise the GI and GL, Professor Jennie Brand-Miller,
I asked him to produce charts that represented a portion of food’s glycaemic load as a number of teaspoons of table sugar (table sugar is an equal mixture of two sugars, fructose and glucose).
Essentially what we did is translate GLs in glucose into a simple table of sugar amounts. The original carb calculations were done by the scientists behind GL — we just made it easier for patients to understand.
For instance, using this system, 150g of mashed potato, when digested, can have the same effect on your blood sugar levels as nine teaspoons of sugar, as do three slices of wholemeal bread.
A small bowl of rice in terms of blood sugar levels is equivalent to ten teaspoons of sugar. A banana can have the same effect as nearly six teaspoons.
Our research (well, our maths, really) was published in the peer-reviewed Journal of Insulin Resistance in 2016. Using the data I went on to create a series of seven ‘sugar charts’ to help show the effect different foods may have on your blood sugar levels.
The charts were recently shortlisted for a prize and then endorsed by the National Institute for Health and Care Excellence (NICE). In 2016 they helped me win the national NHS Innovator of the Year title.
Is a banana really like 6 tsp of sugar?
Of course, like the GI before it, and GL, too, our sugar equivalent charts are just a guide to what can happen to a particular person with type 2 diabetes. There are other factors that influence how ‘sugary’ a food is when digested, including what else you ate with it, your state of health and metabolism.
Some varieties of potato are more ‘sugary’ than others. Also the riper any fruit is, the more sugary it tends to be — a green banana will be less so than a very ripe one.
The point is that the information in the sugar charts works as a general guide, and importantly, it’s now helping many thousands of people with type 2 diabetes to make better choices about the food they eat — and as a result, helping them put their type 2 diabetes into remission.
And as I’ve explained in the Mail previously, low-carb type 2 patients are increasingly using blood sugar monitors to get feedback on their own individual reactions and finesse their low-carb diets.
They do this by using a monitor called the FreeStyle Libre — the system used by ex-prime minister, Theresa May. This is how I found to my shock that a ripe banana doubled my blood sugar an hour after eating it, whereas my wife Jen, an NHS psychologist, is more ‘banana tolerant’.
Can ‘sugary’ carbs give you type 2?
Eating too much of anything will make you put on weight and it’s weight gain, that is linked to type 2. The fundamental cause is probably the modern Western diet of highly processed, high-sugar, fatty foods.
‘Sugary’ bananas or wholemeal bread won’t trigger type 2, but once you have it, they are likely to affect your blood sugar levels in ways you might not expect.
Is there scientific proof it works?
Yes, there is increasing evidence to show that low carb can be very effective for type 2 diabetes.
A 2017 review of nine studies including a total of 724 patients concluded that low-carb diets improved blood sugar and blood fats (reduced the ‘bad’ triglyceride and raised ‘good’ HDL cholesterol).
Then in 2019, a larger review published in The American Journal of Clinical Nutrition that compared the standard low-fat approach with low-carb diets in 2,161 people with diabetes, found that low-carb diets improved blood sugar levels better than low-fat regimens.
It’s research like this that has led to growing worldwide support for the low-carb approach. It has been something of a grassroots movement, with patients — and their GPs — leading the way.
Among them is the GP and writer Dr Clare Bailey, who has just published a study comparing a low-carb approach to usual care for people with type 2. This showed low carb lowered weight and improved diabetes control.
And now, the American Diabetes Association has come round to low carb. A report last year concluded that ‘reducing overall carbohydrate intake for individuals with diabetes’ to improve blood sugar control is the approach with the most evidence. That for patients with raised blood sugar, ‘reducing overall carbohydrate intake with low or very low carbohydrate eating patterns is a viable approach’.
Nearer to home in Scotland, the official guidelines for the Scottish NHS now include an option to reduce dietary carbs to as low as just 50g a day to treat type 2.
Why hasn’t my doctor suggested it?
In the field of nutrition, perhaps more than in any other, experts don’t all agree — and low carb is no exception.
For instance, a study last year in the European Heart Journal found that people on lower-carb diets were more likely to die from any cause than people on higher carb diets.
But, as the authors themselves said, they couldn’t show that low carb caused these problems.
Furthermore, it’s worth noting that the people in the study who ate a lower carb diet didn’t just have a different diet, they were generally unhealthier — older, less likely to be physically active, more likely to smoke, consuming more than four times the alcohol of the higher-carb group, with higher blood pressure and substantially higher incidence of type 2 diabetes.
So perhaps it is not surprising really that these overall unhealthy people were more likely to die prematurely.
I have always said, a low-carb diet should be part of a healthier lifestyle, and exercise has an important role — as I will explain in the Mail next week.
But while there are differences of opinion about which diet is best, there is general agreement that for most people with type 2 diabetes, what matters is finding the best way for each individual to lose weight.
Other options include bariatric surgery or Professor Roy Taylor’s ground-breaking work with a very low-calorie diet. It is a matter of personal choice.
Will I miss out on vital nutrients?
This is a common question as carbs, such as cereals or wholemeal bread, are a source of fibre.
The important point to make about the low-carb approach I offer my patients is the advice to ‘turn the white stuff (rice, potatoes and pasta) green’, by swapping it for salads and green vegetables — which are an excellent source of fibre and nutrients.
Research shows that while low carb is often criticised for lacking B vitamins and fibre — two key components of grain-based foods — in fact it can provide both the vitamins needed and more fibre than we need.
Will I be eating fat that’s bad for me?
On a low-carb diet you can choose to eat ‘good’ fats as contained in nuts, oily fish, olive oil, avocados, and some cream and butter.
The latter may surprise you and I admit to being initially concerned about this, having for years told my patients to avoid these dairy products. But I found the opposite, and last year published a paper with a professor of cardiology that found significant improvements in my patients’ levels of fatty cholesterol and triglyceride.
Our results are mirrored by those in a larger study published in 2018 where the researchers looked at 1,600 people and concluded that ‘carbohydrate restriction appear[s] superior in improving lipid markers [blood fats such as cholesterol] when compared with low-fat diets’.
Isn’t the low-carb diet hard to stick to?
Speaking personally, my wife Jen and I have been low carb for over seven years now — and Giancarlo and Katie Caldesi have been low carb for six.
In a way it is true all diets are hard to stick to. But one factor that really helps my low-carb patients is the diet’s effect on hunger. Repeatedly people say how odd not to feel hungry.
One thing I have learnt is how important the ongoing support of your doctor is. This is where there is potential for continuity of care in general practice. And please note, it is important that anyone on prescribed medication for diabetes should first discuss significant dietary changes with their GP, in case changes in medication need to be made.