How useful are recommended serving sizes and daily intake guides?
Serving sizes on food labels are meant to reflect a realistic portion of the food that a person might normally consume on one eating occasion.
In theory you should be able to use these serving recommendations to monitor and control how much you're eating. But the portion size (the amount you actually eat) and serving size don't always marry up, and following the recommended serving sizes isn't necessarily as sensible or straightforward as it sounds.
Different approaches to serving sizes
In Australia, it's up to the manufacturer to determine the serving sizes, but the system is flawed. Serving sizes are often inconsistent between comparable products, and even within the same brands, and some are simply unrealistic.
In the US, serving sizes are regulated by its Food and Drug Administration (FDA), but this system has also been criticised as being out of date and unrealistic. In many instances serve sizes are smaller than the amounts typically eaten, with critics arguing they understate the kilojoules, sodium and saturated fat people will actually consume as a result.
In Australia as well, in some food categories such as cereal products, serving sizes are lower than the typical reported amounts consumed by adult Australians and those recommended in the Australian Guide to Healthy Eating. So it's not surprising that studies have found that people generally can't correctly estimate the number of servings in a package.
Daily intake guide labelling
Many food manufacturers use these industry recommended serving sizes to determine the daily intake guide (DIG, or %DI) for kilojoules and other nutrients which they display on front-of-pack.
CHOICE has long believed that the DIG labelling system is confusing and requires consumers to undertake complex calculations to use the information effectively, and this was confirmed by the independent panel that reported to Australian government on food labelling
in January 2011.
And more recent research
, commissioned by CHOICE and conducted by The George Institute for Global Health
(TGI) in 2011, found serving sizes vary significantly between similar products in common food categories.
So even if consumers could understand the information on DIG labels, the inconsistent serving sizes on which they are based means they fail to provide consumers with the necessary information to easily compare the nutritional content of similar products.
Serving size research
TGI examined the labels of 1,130 food products across six categories - snack foods, breakfast cereals, cereal and nut bars, ready meals, soups and yoghurts.
In most categories there was a wide range of serving sizes for similar products. All food categories (with the exception of the chilled soup product type) had inconsistent serving sizes and in the most extreme case, the maximum serving size of flavoured and fruit based yoghurts was ten times greater than the minimum.
Products with DIG didn't show any greater consistency in serving size than those without. In some product categories - corn chips, most breakfast cereals, chilled ready meals and canned soup - the average serving size was significantly lower for products with DIG than products without. However, the opposite finding resulted from analysis of extruded snacks, frozen ready meals and yoghurt.
Within the snack food category, data for 337 products was analysed across eight product types, including corn chips, popcorn and wholegrain chips.
• Of 40 corn chip products, serving sizes ranged significantly, with a minimum serving size of 25g and a maximum of 100g.
• Similarly, 32 popcorn products produced an 87g difference between the minimum (13g) and the maximum (100g).
• Potato crisps - the most popular snack food product on record, with 101 products – also produced a significant range between the minimum 19g and maximum 50g serving size.
• Within the snack food category, it was interesting to note that similar products from the same brand varied their serving sizes. For example, Coles Organic Sweet and Salty Popcorn recommended a serving size of just 20g, while Coles Butter Microwave Popcorn had a serving size of 100g.
In the ready meal category, frozen ready meals, also a popular product with 172 labels, proved to be the most difficult to compare, with the maximum serving size (450g) almost four times that of the minimum (115g). Serving sizes also varied greatly within the well-known brands. For example Lean Cuisine Classic Beef Stroganoff with Pasta had a 280g serving size, while Lean Cuisine Rich Beef Lasagne was 400g/serve.
The variation continued in the ready- to-eat breakfast cereal category. The 33 plain adult cereal products surveyed produced a five-fold range between the minimum 10g and maximum 55g serving sizes. Of 110 muesli products, Whisk & Pin Summer Muesli set their serving size at 80g, while the minimum in this category was just 25g.
The only exception to the trend of wide-ranging serving sizes was in the chilled soups product category, where 22 products all set the serving size at 300g.
What's clear from this research is that vast differences in serving sizes occur across the board and the voluntary adoption of the DIG system by the food industry hasn't provided consumers with the consistency they need in order to make healthy decisions.
The expert panel that undertook the Review of Food Labelling Law and Policy, commissioned by the Australia and New Zealand Food Regulation Ministerial Council, presented its final report, Labelling Logic, in January 2011.
The panel studied front-of-pack labelling systems and recognised numerous disadvantages with the DIG system in its final report, including:
• The system's reliance on literacy and numeracy skills
• The significant cognitive processing required to interpret labels may be confusing for some people
• The panel also recognised inconsistent serving sizes as a major issue with DIG labels.
TGI's report further supports the findings.
This research from TGI conclusively confirms what CHOICE has long suspected: that DIG simply doesn't provide consumers with the information they need to compare products easily and make healthier eating choices.
CHOICE believes the Health Star Rating system, which is based on 100g/mL of the product, more easily helps consumers compare products at a glance and identify the healthier options. We're campaigning for all food companies to put health star ratings on their product labels, and calling on the government to reject the confusing DIG system promoted by industry.
Manufacturer-recommended serving sizes can be variable and unrealistic, as the following examples seen by CHOICE in supermarkets demonstrate. So they shouldn't form the basis of a front-of-pack labelling system for our food products.
Comparable products, different serving sizes
Same product, different serving sizes
- A serving of Woolworths Home Brand Quick Oats (30g) vs a serving of Freedom Foods Quick Oats (60g)
- A serving of McCain Healthy Choice Chinese Chicken and Cashews (280g) vs a serving of McCain Healthy Choice Plus Honey Stirfry Chicken (420g)
Unrealistic serving sizes
- A Mars Bar serving is 18g, 36g or 53g depending on the pack size
- A serving of Smith's Chips Original is 19g, 27g or 45g depending on the pack size
- A 225g tub of Bulla Yoghurt Crunch contains 2.25 servings (conveniently, one single serving is just under 600kJ, the generally accepted reasonable energy for a snack)
- A 300mL bottle of Golden Circle Healthy Life Probiotic juice contains 1.5 servings, although people can reasonably consume the whole bottle in a single sitting
- A serving of Domino's and Pizza Hut pizza from their regular range is just one slice; we believe most people would eat at least two or more
To help reduce portion distortion – and control kilojoule intake:
- Eat from smaller plates and bowls and use smaller spoons for serving and eating. One US study found that switching from a 10- to a 12-inch dinner plate (equivalent to switching from a 25cm to 30cm plate) caused people to consume 22% more calories at a meal. Australian research has shown that reducing portion sizes is an effective technique for weight loss.
- Drink from tall narrow glasses rather than short wide glasses. Studies have found that people pour 28-77% more into short wide glasses.
- Pre-portion your foods. Don't eat directly from a box or bag or container that contains multiple servings of a food such as a family size bag of chips or a tub of ice cream. It's hard to keep track of how much you're eating so it's easy to overeat.
- Don't have second helpings.
- Choose the smallest container/cup/plate on offer when buying takeaways. They usually contain more than enough food (and kilojoules).
- Don't be tempted by value meals or supersized/king-sized portions. They may be good value for money, but they're often bad bargains in terms of kilojoules.