ABSTRACT
Portion sizes of foods high in fats and sugars have increased over the last two decades in many countries. Larger portion sizes are contributing to a higher energy intake which in turn is likely to increase the risk of obesity. Experimental studies investigating the links between portion size and obesity are difficult to conduct, whereas short-term laboratory studies of portion size and food intake demonstrated a clear link between portion size and quantity eaten. Observational studies with weaker study design for assessing causality such as cross-sectional studies provide additional information from larger samples of free-living participants. Taken together, evidence suggests that larger portions of energy-dense foods reduce diet quality which may lead to excess weight gain over a period of time. In parallel, portion sizes of nutrient rich foods such as fruits and vegetables are too small. Actions for encouraging more optimal food portions involve many stakeholders such as the food industry, retailers and restaurants and cafes. Reducing portion size of high energy density foods is achievable if done gradually to recalibrate cultural norms and expectations for these foods.
