Sugar And Blood Sugar Levels:

Understanding Sugar's Role in Blood Sugar Management

First what is sugar? 

Sugar isn’t just the white stuff that you can add to cake and tea. It is also referred to as dextrose, maltose, glucose, sucrose, fructose on the back of a packet. In fact, if a word ends in -ose then it’s probably a form of sugar. The sugar that you add to cakes is cane sugar which is 50% glucose and 50% fructose bound together.


When you eat sugar in any form, your blood sugar rises to supply your body with energy. When your blood sugar rises, the hormone insulin is released into the bloodstream to remove the glucose (sugar). Some glucose is used by the body and goes to the muscles and brain, where it is used as energy, but any excess goes to the liver. The liver then turns this excess into fat as storage to be used another day. However, if you are constantly supplying your body with food and therefore energy, then your body won’t use this surplus and so it will continue to remain as fat.


Balancing your blood sugar.

The key to successful weight loss is the balance your blood sugar and to keep levels on a steady plateau rather than highs and lows. It’s when your blood sugar drops that you start to feel hungry. What happens when you eat a food high in sugar is that your blood sugar levels rise dramatically causing a spike in your blood sugar levels. This might feel great at the time – but what goes up must come down and often with a bang. The result several hours later is mood swings, feeling agitated, low energy levels and intense sugar and carbohydrate cravings. This then leads to eating more sugar and up you go again! When your blood sugars are in a healthy range then you will feel energetic and alert. It’s only when these blood sugars drop too low that tiredness and lack of concentration sets in.


You want to try and choose foods that have a more stable effect on your blood sugar levels. This is food with a lower glycaemic load. Low glycaemic foods include beans, chickpeas, fruit, lentils and whole-grain bread. Medium glycaemic foods are oats, spaghetti, brown rice, sweet potato and white bread. High glycaemic foods are cereals such as cornflakes and rice krispies, dates, white rice, white potato and raisins. This isn’t to say that you shouldn’t eat these high-glycaemic foods – but you need to be aware of the effect on blood sugar and make sure that you consume with some protein and fat to slow down the effect in the bloodstream.


Foods with a low-glycaemic load also encourage your body to burn fat, which if you are looking to lose weight is what you’re aiming for! A study (ref. below) found that feeding people a low glycaemic meal and then putting them on a treadmill 3 hours later meant they burnt more fat than they would have done after eating the same number of calories of a high-glycaemic meal. Lower-glycaemic foods are likely to make you feel fuller for longer and so will result in eating fewer calories.

A study (ref. below) found that if you match two types of meals for calories – but one has a high-glycaemic load and the other low, the meals with the higher glycaemic load activate parts of the brain associated with reward and craving – and resulted in an increased hunger four hours later.


What about fruit?

Fruit mainly contains fructose and therefore is classed as a sugar. However, it is a slow releasing sugar as your cells can’t run on fructose alone, it needs to be converted to glucose. This act of converting the fructose to glucose slows down the sugar’s effect on the metabolism and so your blood sugar doesn’t rise as quickly. Some fruits, such as dates and grapes, contain pure glucose and so will have a greater effect on blood sugar levels. Others, such as apples contain mainly fructose and so are a good option. Bananas contain both fructose and glucose and can also have a speedy reaction on blood sugar levels. Berries have a very slow releasing effect on your body and are a very good option.



The influence of high-carbohydrate meals with different glycaemic indices on substrate utilisation during subsequent exercise. Ching-Lin Wu et al. Br J Nutr. 2003


Effect of dietary glycaemic index on brain regions related to reward and craving in men. Belinda S Lennerz et al. Am J Clin Nutr. 2013

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Author: Katherine Bright MBANT, CNHC