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  • Sugar, a luxury in the past but now part of our daily diets, is contributing to weight gain. It’s found in our drinks and most processed foods either as sucrose (table sugar) or high-fructose corn syrup (a mixture of fructose and sucrose).

    The spotlight in recent months has turned particularly on fizzy drinks, which can contain high amounts of fructose, offer little in the way of nutritional value and satiety (that full feeling) and, unfortunately, as we all know, are very easy to consume.

    The 1 February 2014 issue of New Scientist magazine includes a cover story on the health effects of consuming sugar. The international article includes a section on a study by Dr Lisa Te Morenga and her colleagues from the University of Otago.

    Listen to this Radio NZ Our Changing World programme: Sugar: Desirable But Deadly which features Dr Lisa Te Morenga.

    In 2013, the Science Learning Hub reported on the study commissioned by the World Health Organisation and published in the British Medical Journal, see the article New weight-loss research.

    Sugar intake and body weight

    The researchers found that reducing free sugars in the diet has a “small but significant” effect on body weight in adults. Increasing sugar intake was associated with a corresponding increase in body weight, which is reported to occur comparatively rapidly. The weight loss or gain keeps on going for as long as a subject continued on an increased or decreased consumption of free sugars. For sugar-sweetened beverages, the risk of being overweight or obese increased among children with the highest intake of sugary drinks compared with those with the lowest intake.

    The authors of the research conclude that, while obesity has many causes, “when considering the rapid weight gain that occurs after an increased intake of sugars, it seems reasonable to conclude that advice relating to sugars intake is a relevant component of a strategy to reduce the high risk of overweight and obesity in most countries”.

    A contentious issue

    The issue is contentious (as things often are when there are economics involved), just as the effects of tobacco used to be, but it seems with free sugars (sugars that are added to our food and drink and sugars found naturally in syrups and fruit juices), we wind up consuming more calories than we need. There is even some suggestion that sugar may be addictive, leaving us craving more and leading to overeating. Many researchers note the timeline correlation with our first-world bulging waistlines and the almost ubiquitous addition of high-fructose corn syrup to processed foods and beverages (particularly in the United States) since the 1970s, although it should be again be stressed that several factors contribute to obesity, including sedentary lifestyles.

    According to the New Scientist article, “between the early 1970s and the early 2000s, adults in the US increased their average daily calorie intake by 13%, largely by eating more carbohydrates, including sugar. In 1996, the average US adult swallowed 83 more calories per day from added sugar than in 1977. Today, yearly sugar consumption in the US is close to 40 kilograms per person – more than 20 teaspoons a day.”

    New guidelines on the way

    The World Health Organisation (WHO) is working on new consumption guidelines that recommend free sugars form only 5% of daily calories (down from their earlier 10% recommendation) or about 8 teaspoons a day for men and 6 for women. For some context, a 355 ml can of cola contains the approximate equivalent of 10 teaspoons (39 grams – 4 grams per teaspoon). This is irrespective of the type of sugar used (or more accurately, the relative percentage of fructose/sucrose in the added sweeteners).

    Natural sugar in fruit, veges, milk still OK

    These sugars are not to be confused with sugars that occur naturally in fruit and vegetables, or the lactose in milk. As far as nutritionists are concerned, these fall into some sort of ‘naturally occurring’ loophole where the nutritional content and/or fibre value of such foods give the sugar content a get-out-of-jail-free card.

    Activity idea

    Increased sugar intake is one of many factors that contribute to obesity. In Obesity risk factors activity students participate in a simulation demonstrating that both genetic make-up and environmental factors influence an individual’s likelihood of becoming obese.

    Related content

    Read the related article Academics consider case against sugar.

    Useful links

    Read the 2015 Who report Guideline: Sugars intake for adults and children.

    In 2022 the Health Star Rating system was upgraded, making it tougher on sugar and salt – read the press announcement on the MPI website.


    O’Callaghan, T. (2014). Sugar on trial: What you really need to know. New Scientist. Iss. 2954. (Published 1 February 2014).

      Published 4 March 2014, Updated 7 August 2020 Referencing Hub articles
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