Benefits of maintaining reasonably stable blood sugar

At the time of writing, I am wearing a continuous glucose monitor, because I am participating in a study being conducted by the Epidemiology Unit at the University of Lausanne. The study asks me to monitor my glucose, to track my food intake and my activity levels, and to eat standardised breakfasts, to see what happens to glucose levels. It’s been fascinating to see my blood sugar levels climb fast after a meal of white bread, (which I never normally eat!) and then drop rapidly as the pancreas releases insulin to balance my sugar levels. Insulin prepares the cells to receive the glucose, which they need, and the sugar levels return to normal. It’s also interesting to see how a meal of protein, fat and veg does very little to my sugar levels.

Why is it important to have reasonably stable blood sugars? Well, a few reasons: consistently high sugar levels (hyperglycemia) can lead to insulin resistance, which means that the cells become less sensitive to insulin, and won’t allow entry to the glucose. Over time this can lead to diabetes.

If you want to lose weight it’s also really important to stabilise your blood sugar. Because if your sugar levels shoot up after eating refined carbohydrates, they will drop again quickly, and then you feel hungry again. Processed, refined carbohydrates drive sugar levels high, there is a strong insulin response from the body which drives them low again, and then you’re hungry again! This is why a low fat, high carb diet is so difficult to stick to – it’s keeping you hungry!

Tim Noakes and the Banting diet

In South Africa, around 2012, we all heard about the controversy surrounding sports scientist, Prof Tim Noakes, and the Banting diet, which is essentially a low carb, high fat diet. Prof Noakes, who had previously always advocated a high carbohydrate diet for athletes, did an about-turn and began to promote the Banting diet, a ketogenic diet, to control blood sugar levels and for weight loss. Initially Noakes was roundly condemned and disparaged by the scientific community. I would say that Noakes at that stage was acting on a well-informed hunch, backed up by some research at that time, and on his own body’s negative response to carbohydrates, as well as his weight loss and feeling of wellbeing on a ketogenic diet. The diet became hugely popular in South Africa, affecting what restaurants served and what supermarkets sold, and had benefits for many people.

Much has changed since then, and much more research has come out that supports Noakes’ theory: a low-carb, high fat diet can be effective for weight loss, for stabilisation of blood sugar levels, for brain health, and even for  prevention and treatment of some forms of cancer. But it is not for everybody, and it may not be optimal to stay on it for the long term. For an excellent overview of this research, go to

So what is a ketogenic diet and is it for you?

It’s a high fat, moderate protein, low carb way of eating. Typically you eat 60 to 75% of calories from fat, 15-30% from protein, and 5-10% from carbohydrates. Most people, when they see that you should consume a considerable amount of fat, are horrified.  Many of us have been brought up in an era when we were told that the low fat, high carb diet is healthiest. I was one. I remember going to a dietician for help with weight loss, and she told me to stick to around 5g of fat a day. That’s a tiny teaspoon of olive oil! We now know that fats are healthy, (except for trans fats and industrial seed oils!) and that for most people, even good saturated fats, like coconut oil and butter, are healthy. However many doctors, most of whom know little about nutrition, still recommend low fat, high carb diets. And as we’ve seen, high carb diets, especially when they consist of  mostly refined carbs, play havoc with your sugar levels. And that drives hunger. However, and this is important, there are complex carbohydrates, such as sweet potato, whole fruits like berries or plums, or oats, that do not play havoc with your sugar levels. You have to find what works for you.

A ketogenic diet allows your body to gradually become fat adapted, ie it learns to rely on fat and ketones as fuel, and not on glucose. Ketones are produced by the body and used for energy, when the body is in “nutritional ketosis.”  If you like, you can test your ketone levels with urine strips or a prick of your finger. Being in ketosis has a lot of benefits. Your body burns fat to provide you with energy. Fat, especially together with protein, is satiating, so you are not as hungry. The brain likes to run on ketones, too. There is new research that neurodegenerative disease, such as Parkinson’s and Alzheimers, may be linked to brain insulin resistance, where the neurons don’t get the glucose they need. Ketones are an excellent alternative fuel for the brain.

There are some people who should not attempt a ketogenic diet

  • if you’re pregnant or breastfeeding, if genetically metabolising fat is not optimal for you, or if you have had your gall bladder removed. (The gall bladder’s role is to break down fat). The body does, however, adapt to not having a gallbladder, and so this is individual – you will know if you are digesting the fat well or not.
  • Also if you have high cortisol levels, and are really stressed, a ketogenic diet may add to that stress.
  • While most people can eat a lot of fat and there is no impact on their cholesterol, for some people, especially those who have familial high cholesterol, this is not the case. Athletes too, especially those who do explosive movements needing muscle power (eg martial arts) need more glucose. However endurance athletes may do really well on a ketogenic diet as they can do long distances fuelled on their own body’s fat.

The most sensible advice seems to be to follow a cyclical approach, i.e first allow your body to become fat-adapted by following a ketogenic diet for a few weeks. (This may be difficult in the beginning as the body adapts. For more advice, recipes and tips on keto diets go to After that it’s probably best to switch between a higher carb diet – say 30% carbs, (but always complex carbohydrates, never processed carbs – just add some fruit and more root vegetables) and the ketogenic diet. Trying intermittent fasting, too, where you eat all your meals say within an 8 to 10 hour window, is a good way to enter into ketosis.

It’s about experimenting! Every body is different, and you have to find what’s right for you. Tune into your own body and see how it responds. But give it time when you start a keto diet – the body may protest in the beginning, but later you may feel the freedom of less hunger and more stable blood sugars.