Researchers at the University of Illinois at Urbana-Champaign in the US served a free soup lunch to 54 adults, half of whom ate from normal 18-ounce soup bowls, while the other half ate from identical bowls that, unbeknownst to the participants, were slowly refilled through tubing connected to out-of-sight soup cauldrons.
Those who ate out of the refilling bowls consumed 73 percent more soup than did participants who ate from the normal soup bowl during the 20-minute lunch. Although they averaged 113 more calories than those eating from normal bowls, those eating from the bottomless bowls believed they consumed the same number of calories as the other participants and rated themselves as being no more full.
"People use their eyes to count calories and not their stomachs," said lead researcher Brian Wansink, professor of marketing and of nutritional science at Illinois. "This can be dangerous to our diets."
Because we appear to judge our food intake by visual cues, such as an empty bowl, Wansink said that people worried about overeating should carefully consider the size of portion servings in restaurants and in their kitchens.
He suggested, for example, repackaging snacks and other bulk foods into small plastic bags. The visual cues from the filled bags can lead individuals to think that a smaller-than-normal serving was a satisfying full serving. This underlines a possible new trend in packaged food, where the portion size is directly related to tackling the issue of obesity, and where information is clearly stated or even defined by specific guidelines.
The issue has certainly gained momentum, and in many countries has now entered mainstream political discourse. Recently released figures suggest that in excess of 200 million adults across the EU may be overweight or obese.
Obesity, defined as a Body Mass Index over 30, is a risk factor for a host of illnesses including heart disease, hypertension and respiratory disease. According to the Commission, obesity accounts for between 2 to 8 per cent of healthcare costs in Europe.
The food industry is therefore finding itself increasingly on the front line. Regular working groups looking at the issues of consumer information and education and promotion of physical activity, are also beginning to investigate the composition of food and portion sizes, as well as marketing and advertising.
New voluntary labelling initiatives have already been implemented in the EU and a tighter code of advertising could be on the way. Indeed the food industry is fearful that the Commission might eventually draw up legislative proposals for food labelling and advertising.
But while the issue of obesity is perceived by some to be a threat to the industry, it is also an opportunity. Food manufacturers are already tapping into the growing trend for health positioned products. French consumers alone spent €360 million on functional foods and drinks in 2002, with Datamonitor forecasting spending to rise by 40 per cent to €506 million in 2007.
Market analysts Datamonitor claimed earlier this year that the numbers of functional food consumers in major European markets are growing each year by around 6 to 7 per cent. With the European food industry spending an approximate 3 to 4 per cent on R&D, new product design to formulate foods that push health benefits will play a fundamental role.
There are already signs that changes in consumption patterns are underway. A recent report from Mintel shows a significant difference in some advertisers' spending on promoting their products to children.
Masterfoods, for example, spent €8.21 million on promoting its Mars bar tin UK children's media in 2000, but this had dropped by a massive 71.4 per cent by 2003, to €1.72 million - a change attributed to growing consumer concerns about health.
The University of Illinois paper, entitled "Bottomless Bowls: Why Visual Cues of Portion Size May Influence Intake," was co-written by James E. Painter, a professor of family and consumer science at Eastern Illinois University, and Jill North, a graduate student in food science and human nutrition at Illinois. It appears in the current issue of Obesity Research, a leading nutrition journal.