To the Editor: Over the past 20 years, the prevalence of obesity in the Australian population has more than doubled — from 8.1% in 1981 to 20.5% in 2000.1,2 The rapid and widespread nature of the obesity epidemic suggests that environmental change is a major contributing factor.

The patterns and types of foods consumed by Australians have changed markedly within a single generation. One major area of change is the availability and consumption of "fast" foods.3 A key feature of fast-food marketing is the use of "upsizing", a strategy designed to provide the consumer with a "value-for-money" addition to their meal. Upsizing is commonly employed within the context of "meal deals": complete meal options comprising the major food item (burger or chicken product) and, for a small extra cost, larger serving sizes of items such as hot chips and soft drink. Recent data from a US survey have shown that upsizing provides disproportionate increases in energy content relative to purchase cost.4 However, no published data have demonstrated the impact of point-of-sale fast-food upsizing on total energy, fat and sugar availability for Australian fast-food meal-deal options.

On 28 July 2002, we purchased major meal deals and the advertised upsizing portions from the four major fast-food chains present in most large Australian cities: McDonald's, KFC, Red Rooster and Hungry Jack's. In order to assess six portions of each meal deal, we purchased two from each of three outlets. The weight and volume of chips and soft drink (non-diet variety) were measured, and nutrients were analysed using the AusNut and AusFoods Australian food databases.5 A summary of our findings is presented in the Box. On average, a 12% increase in purchase cost increased energy availability by 23%, with a 25% increase in fat (10.3 g) and a 38% increase in sugars (18.8 g). The upsizing meal option providing the greatest energy gain was the "fillet burger combo" from KFC (50% increase in energy for a 16% increase in cost). Large meal deals provided on average 5733 kJ (35.4% energy from fat and 21.4% energy from sugar).

Based on data from the 1995 National Nutrition Survey, these single meal deals constitute 52% and 77% of the average daily energy intake of male and female Australians, respectively.6

Upsizing is a marketing strategy aimed at increasing the purchase cost of the items by providing the consumer with an added incentive or greater value. Using this strategy, upsizing meal deals double the energy gain relative to the additional cost. Importantly, upsizing also increases fat and sugar intake. With the growing disease burden of overweight and obesity on the Australian healthcare system, the public needs to be aware of the passive increase in energy consumption that can occur in pursuit of "value-for-money" eating options. Excess consumption of sugar and fat from fast-food meal choices adds mainly "empty calories" to the diet, with little nutritional gain and with a real risk of expanding the nation's waistline.