“Don’t dismiss the importance of sugar in a healthy diet” say Ellern Mede dietetics team. It’s a fact that your brain needs glucose to function. So have we gone too far in cutting out sugars? People with eating disorders often think it’s something to avoid as they get so focused on their treatment programme.

The following quote is from a University of Toronto nineties research paper by G.H Anderson published by the National Centre for Biotechnology Information library:

“There is now considerable evidence that the concern about sugar consumption as reflected by the media in the 1970s was misplaced. Knowledge of sugar consumption has led to the conclusion that current consumption levels are consistent with the achievement of healthful diets. The myths surrounding sugar and health, including the myth that sugar causes hyperactivity, are slow to disappear. Because these myths are misleading and harmful, nutrition educators need to continue to place sugar in the diet in perspective.” 1

As a Dietetics service dealing with active and growing young people who have anorexia nervosa, our balanced perspective about sugar and its place in nutrition must take into account its value. Frequently people with this condition ‘stigmatise’ certain foods. Unfortunately, sugar is particularly in this category. We think its time to take a second look at the evidence and offer some practical guidelines.

Sugar – a sad reputation for a very important food source

With a society focused on the health dangers of fast food and sedentary lifestyles, sugar is often blamed and so for health-conscious people this is a message that is perhaps taken to the extreme. The fact is, a diet excluding sugar would result in the body ceasing to function properly. Sugar plays an important role in a number of bodily functions.

National Guidelines – a helpful but sometimes misinterpreted information source

Public Health England recommends that ‘sugar’ should make up a maximum of 5% of an individual’s daily intake. However what this 5%actually refers to is not ALL sugar but the quantity of ‘free sugar’ or ‘added sugars’ in the diet.  These are sugars added to drinks, food, or in fruit juice, honey or syrup. The guidelines do not mean you should restrict the sugars that occur naturally in fruit, vegetables or milk, or those found in carbohydrates.

A growing young person requires between 2400 and 3000 kcal.  Expressing 5% of that in terms of added sugar would be 120-150 kcal of free sugar daily. In terms of grams, this would equal 30-38g of granulated sugar. (NHS Choices 2 states 30g of sugar daily). This is reasonable, but unfortunately, it is often not what people understand to be the case. Previously guidelines had recommended a figure of 10% of free sugar as intake. A common mistake-over time misinterpreted this as 10g of sugar. Clearly, a dietary intake of  10g of sugar a day is too low.

Functions of Sugar

As sugar is a carbohydrate, it acts as the main source of fuel for the body. Simple sugar acts as an immediate source of energy, whilst complex sugars are able to provide the body with long-lasting energy. Sugars are converted into glucose by the body and transported to cells. Here, glucose is converted into a high-energy molecule which supplies cells with fuel for functions such as muscle contraction. Sugar is particularly important for brain function. This is because the brain depends solely on glucose as a source of fuel, whilst other organs are able to use different sources of energy if glucose is unavailable. This is why low blood sugar level is linked to both poor attention and impaired cognitive function (Mergenthaler et al., 2013).

Energy Storage
When more sugar is eaten than what is needed by the body at the time, it is converted to glycogen and stored in muscles and the liver (Berg et al., 2002). When blood sugar levels are low e.g. between meals and whilst sleeping, these stores can be used to fuel organs which require glucose as an energy source, such as the brain. Excess carbohydrates can also be converted to fatty acids and triglycerides and stored in fat tissue (Shchutz, 2004). Many people with anorexia nervosa have minimal fat stores. Inadequate fat stores affect hormones vital for normal growth and development.

Inadequate sugar will indirectly impair muscle tissue
Although the body’s preferred energy source is carbohydrates, when sugars are scarce the body may turn to other sources of fuel, such as amino acids from dietary protein. As a result, these amino acids cannot be used for other functions such as building muscle/maintaining muscle mass. I.e. sufficient intake of dietary carbohydrates (including sugars) can help conserve muscle tissue. This is important for young people with anorexia nervosa who often present with muscle wastage on admission to hospital for treatment.

 Myths and Facts about Sugar

Myth Fact
Unrefined sugar is healthier than refined sugar


Both have the same energy content and are treated by the body in the same way.
Brown sugar is healthier than white sugar


Brown sugar is darker in colour due to containing a higher level of molasses (which contains certain minerals, however in minuscule amounts). There is no health benefit to using brown sugar.
Sugar provides ‘empty calories


Sugar is rarely eaten on its own. It is used to contribute to the colour, flavour and texture of food which can improve its taste and palatability, therefore increasing the range of foods people can eat.
Eating sugary foods causes a fluctuation in blood sugar levels


For healthy people fluctuations in blood sugar levels are not an issue. Eating sugar actually causes a smaller rise in blood glucose than eating starchy foods such as white bread/rice. When sugar is added to some foods (e.g. breakfast cereals) it can actually lower the glycaemic index (blood glucose raising ability) of the product.
Sugar is addictive


Scientific studies do not support the hypothesis that sugar may be physically addictive. In humans there is no evidence that a specific food/ingredient or additive causes a substance-based type of addiction.
Eating sugar will make me gain weight


Changes in weight occur as a result of an imbalance between energy expenditure and intake from all types of food and drink.
Foods labelled as ‘reduced in sugar’ contain less energy. This is not necessarily true. Often these products replace sugar with other ingredients which may result in little or no reduction in energy.

 An example of a Diet suitable for a growing teenager

Below is a menu for a diet plan of approximately 2500 kcal indicating grams of sugar content:

Glass of juice-10 g
Bowl of cereal- 5 g
Toast with spread and jam- 5 g
Morning Snack
Cereal bar-10 g
Main meal-n/a
Yoghurt -15 g
Afternoon snack
Glass of milk-n/a
Chocolate bar-20 g
2 x biscuits-5 g
Glass of milk-n/a
Portion of fruit-n/a

Total sugar = approximately 70 g = 280 kcal = 11.2% of intake

Comment on the above diet plan
Most people would agree the above meal plan to be one of a normal and balanced diet. However, when looking at sugar content, approximately 11.2% of the calorie intake is from sugars -that is over double the 5% that a person might think they should have if they were reading generally accepted guidelines. Although helpful, this 5% figure is far too low for a teenager and certainly too low for a teenager who is already malnourished through an eating disorder. Ellern Mede supports young people with eating disorders to become more comfortable with ‘treat style foods’ such as chocolate and biscuits. This is an essential part of their treatment and one of our main aims is to de-stigmatise certain foods/drinks that are all too often labelled as ‘harmful’ in the media. We include high sugar treat foods as snacks on patient menus occasionally because it is important that they are using sugar and carbohydrates as their main source of energy in order to prevent loss of muscle mass and to help build and maintain fat stores.

To conclude, sugar is an important source of energy for the body. It is important for brain function and meeting requirements helps to prevent protein being used for energy. This is particularly important patients with anorexia nervosa who often need to build up their muscle mass after a period of starvation. Guidelines do recommend 5% of daily intake to come from sugar, however it is Ellern Mede Dietetics Team’s view that this recommendation should not apply to young people, and particularly not to young people with eating disorders due to our focus being on de-stigmatising certain foods and helping our patients meet their high energy requirements.

Useful references

1. https://www.ncbi.nlm.nih.gov/pubmed/1807277 (accessed 3 September 2017) G.Anderson research paper. Department of Nutritional Sciences Faculty of Medicine, University of Toronto, Ontario, Canada.
2 NHS.2015.How much sugar is good for me? [ONLINE] Available at: http://www.nhs.uk/chq/Pages/1139.aspx?CategoryID=51. [Accessed 1 September 2017].
3. Mergenthaler, P., Lindauer, U., Dienel, G., Meisel, A., 2013. Sugar for the brain: the role of glucose in physiological and pathological brain function. Trends in Neuroscience, 36(10), p587-597.
4. Berg, JM., Tymoczko, JL., Stryer, L., 2002. Biochemistry. 5th ed. New York: W H Freeman.
5. Shchutz, Y., 2004. Dietary fat, lipogenesis and energy balance. Physiology and Behaviour, 83 (4), 557-564.