There has been a trend over recent decades for food to be served in larger portion sizes. This portion growth applies equally to food purchased out of the home and food served at home. As portion sizes go up, people can easily eat more than they intended.
As a way to help address ‘portion creep’, a research team designed a program to help educate a group of people on controlling portion size as part of an ongoing weight loss intervention.
Three groups of women, some of whom had already completed a one-year weight loss trial that included portion-control strategies, visited a food lab once a week for four weeks. At each visit, the women were given the same foods to eat, but portion size varied. Each meal had a range of foods with a high kilojoule density like chocolate-chip cookies as well as lower kilojoule density foods such as a salad.
When larger meal portions were served, the women ate more food which was an expected finding. For example, when the portion size was increased by 75 per cent, 27 per cent more food was eaten.
The novel finding of the research was how the food choices differed. Women who had already undertaken portion control training ate more of the lower kilojoule-dense foods and less of the higher kilojoule food. That meant compared to women who had no portion control training, even though the volume of food eaten was the same between the groups of women, the overall kilojoule intake was lower because of eating more of the less kilojoule-dense options.
Choosing to eat greater amounts of healthier lower kilojoule-dense foods such as fruits and vegetables is a more effective and sustainable approach to eating than just trying to resist or control portions of higher kilojoule foods.