Sugar & Sugar Free Diets

By Charlotte Foster BSc (Hons), MSc, RD.

Talk on following a “sugar free” diet has become so prevalent in recent years that I’m pretty sure that even tribal communities in far flung regions of our planet have had conversations about this latest dietary craze!

We feel it is important to examine the evidence around the concept of the sugar free diet by looking at some key points.

What is sugar and can we actually eat a diet which is sugar free?

The problem today is that there is a liberal use of the term sugar which has instilled fear into food lovers.

Fact – most foods will contain sugar. The term “sugar-freer” seems to have been used as a marketing tool and attached onto a plethora of food products/ recipes and diets. The problem is, it has left us more confused than ever before about what is in our food and what implication that does or doesn’t have on our health.

So let’s unpick the different definitions to discover the sweet truth!

The definitions of sugar…

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  • Carbohydrates – organic compounds made from molecules of carbon, hydrogen and oxygen. “Carbohydrate” refers to sugars, starches and cellulose (fibre) and contributes as a source of energy in the diet for many animals. They are categorised by their chemical structure into monosaccharides, disaccharides, oligosaccharides and polysaccharides.
  • Starch- Many dietary sources of starches (e.g. rice, potatoes and cereal grains) will provide B vitamins, iron, and folate. In the UK, potatoes provide a large dietary source of vitamin C (usually containing ~11-16mg of vitamin C per 100g of potatoes) because we eat so many of them!
  • Fibre – structurally they are classified as polysaccharides (3 or more monomers) and are found in plant sources. They are neither digested nor absorbed in the small intestine. There are soluble and insoluble forms of fibre, both of which are needed in the diet for a healthy digestive system (to help with stool formation).
  • Naturally present sugars – e.g. found in fruits as fructose or in dairy products (such as milk and yoghurt) as lactose.
  • Refined sugars (processed sugars added to foods) – These come from sugar cane or sugar beets, which are processed to extract the sugar. It is typically found as sucrose, which is the combination of glucose and fructose.
  • Intrinsic sugars – integrated into the cellular matrix of foods e.g. sugar found in fruit and vegetables
  • Extrinsic sugars – sugars that are not integrated into a cellular matrix e.g. lactose in milk.
  • Non-milk extrinsic sugars (NMES) –sugars that are not integrated into a cellular matrix and not from a milk/ dairy source e.g. honey, fruit juices, table sugar. This term has now been replaced by “free sugars”.
  • Free sugars – alternative name for NMES (see above).

Where did concerns over the health effects of sugar arise from?

A lot of concern and discussion around sugar arose off the back of a commentary by a Professor of Clinical Paediatrics at the University of California  (1). This commentary expressed the author’s opinions on the role they believe sugar has to play in the development of diet-health related disease and was not a robust scientific review or a presentation of novel research (1). However, they do mention a couple of published research papers to support their case, one of which is written by Lustig (introducing possible bias) (1).  Also, there was no critical appraisal (carefully critiquing the results to decipher their impact) of the evidence regarding the relationship between sugar and diet-related disease development. It would seem that these headlines may be portraying a slightly false picture.

A report published in 2015 by Scientific Advisory Committee on Nutrition (SACN) looked at randomised controlled trials and found that sugar-sweetened drinks (compared to low calorie drinks) resulted in increases in weight gain and body mass index in children and adolescents. It is being overweight which increases a risk of diet-health related diseases.  SACN’s report emphasised that no association between developing type 2 diabetes and total or individual sugars intake. However, prospective cohort studies associate greater consumption of sugar sweetened drinks with an increased risk of developing type 2 diabetes (2).

Should we try and reduce our sugar consumption?

We are all individual and therefore this is not an easy question to answer.

Sugar is a highly dense source of energy (calories) and so can be useful for those trying/needing to gain weight. Dietitians may recommend having high energy containing foods/ fortifying your diet with sugar based foods as strategies for adding extra energy in a concentrated food source. This is often the same with fat sources.

However, for many, the sugar content of the diet is something to watch out for. Excess sugar in the diet could mean excess energy (calories) intake. This may lead to weight gain. It is the weight gain (being overweight/obese) that puts us at risk of diet reacted diseases such as type 2 diabetes and heart disease.  People with diagnosis of diabetes may be advised to limit the amount of sugar in the diet or advised to “carbohydrate count” in order to adjust medications and insulin regimens.

How much sugar should we have according to healthy eating guidelines?

Recent guidelines published in July 2015 by SACN advise that the average intake of “free sugars” (previously known as non-milk extrinsic sugars ) should be no more than 5% total energy intake.  This is half of the previous recommendations for 10% total energy intake (3).

5% of total energy intake (as calculated by Public Health England) means:

  • no more than 19g/day of free sugars for children aged 4-6 year olds (3)

This equates to ~ 5 sugar cubes!

  • no more than 24g/day for 7-10 year olds (3)

This equates to ~ 6 sugar cubes!

  • no more than 30g/day 11+ year olds (including adults) (3)

This equates to ~ 7 sugar cubes!

The report highlighted that only 13% (1 in 8) of adults already achieve this 5% recommendation!

How to interpret sugar – label reading…

Sugar can be given a variety of names so the skill of label reading becomes important when analysing a food’s nutritional composition.

Labels on food packaging will state “Carbohydrates” and “Carbohydrates (of which sugars)”. “Carbohydrates” refer to the starchy carbohydrate content as well as the sugars and so should not be used as a sole interpretation of a food’s sugar content. The “Carbohydrates (of which sugars)” figure refers to the sugar content in the food – including naturally occurring sources found in milk or fruit as well as added sugar.

  • High– over 22.5g of total sugars per 100g
  • Low – 5g of total sugars or less per 100g

Be aware!  Sugar is not only present in “obvious” sweet tasting processed foods e.g. cakes/biscuits/ chocolates or sweets, but can be added sneakily to savoury snacks, salad dressings and pasta sauces etc.

Therefore, in order to work out whether a food contains lots of added sugar, you need to check the ingredients list.


Hopefully the list above has highlighted something important… just because “table”/ “caster”/ “granulated” SUGAR may not be listed, it doesn’t mean it’s sugar-free!  These are all sources of sugar (some are natural and found in less processed foods).

This is often where the confusion arises. Many glamorous recipes for batches of sumptuous “sugar-free” brownies will in fact contain plenty of sugar in the forms of honey/ maple syrup/ agarve syrup/ dates or some other dried fruit!

Perhaps these recipes should be renamed “wholefood” or “less processed” rather than “sugar-free”. There is no denying that these recipes contain superior nutritional profiles compared with refined, processed or manufactured versions, but that is often not what is being promoted.

Our hope is, that with a better understanding of the term “sugar”, you will be able to see past this marketing ploy and make an informed decision on how regularly this appears in your diet.

Key take home messages:

  • Sugar has many definitions – watch out for the context of this term i.e. carbohydrates are different to refined sugars
  • Many foods contain high sugar contents; just because it isn’t called “sugar” doesn’t mean it isn’t a source of it.
  • We must consider the food’s overall nutrient profile – what other nutritional benefits does it provide?

For example orange juice vs a full sugar cola drink.

Orange juice though also high in sugar, if “not from concentrate” will contain vitamin C and 150mls will count as one of your 5 a day. Whereas a full sugar cola drink merely contains a sugar hit, caffeine and empty calories.

  • Sugar can still form part of a healthy and balanced diet – it is the amount that we have in our diet which we need to consider.


(1): Lustig, R.H., Schmidt, L.A., Brindis, C.D. (2012) Public health: The toxic truth about sugar. Nature 482; 27-29.

(2): SACN (2015) The Scientific Advisory Committee on Nutrition’s recommendations on sugars. Available at [last accessed 24/03/16]

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