Globally, an estimated 43 million children under five years of age were overweight in 2011 – a 54% increase from 1990 (1). Overweight and obese children are at higher risk of developing serious health problems including type 2 diabetes and high blood pressure (2). Childhood obesity also increases the risk of obesity, noncommunicable diseases, premature death and disability in adulthood (3,4).

As the rates of overweight and obesity have increased over the last several decades, so too have portion sizes in restaurants, supermarkets and homes (5) suggesting that larger portion sizes may play a role in the obesity epidemic (6). Although a direct, causal relationship between portion size and obesity has not been demonstrated, current research indicates that energy intake in children and adults is influenced by the size of the served portion, with larger served portions resulting in significant increases in energy intake (7-13). The impact of portion size on energy intake may be less pronounced in younger children, however, as studies have shown that children under three years of age are often better able to self-regulate their energy intake than older children (7). These findings seem to suggest that as children age, internal hunger and satiety cues may become less effective at moderating dietary energy intake, and external factors such as portion size begin to play a more important role (9).

As providers and preparers of food in most households, parents also play an important role in determining not only which foods, but how much food children consume. Available information suggests that it can often be difficult for many parents to assess appropriate portion sizes for children and thus they may inadvertently contribute to the problem of overeating in children (14,15). Further evidence suggests that the increasing single-serving sizes (i.e. portion of food or drink that is intended to be consumed in one sitting) of commercially available foods may condition individuals into believing that larger portion sizes are normal, which may not only lead to overconsumption of those foods, but can also be translated into larger portion sizes of home-prepared meals (16).

Behavioural interventions aimed at reducing portion sizes by teaching children to focus on internal cues of hunger and satiety - eating only when they are hungry, eating slowly and recognizing when they are full - may help prevent overeating (9). Limited evidence suggests that allowing children to serve themselves may also help, as some children have been shown to serve themselves appropriately sized portions when given the opportunity (8,17). Other changes to eating habits such as the use of smaller, “child-sized” serving bowls, utensils and plates may also be effective at limiting the amount of food consumed as demonstrated by a small number of studies (18,19). Interventions designed to improve knowledge of appropriate portion sizes for children among parents and caregivers may also help them to make better decisions about their children’s nutrition.

While behavioural interventions may change eating patterns and attitudes of children and their parents and caregivers, changing the food environment through regulatory actions could lead to a reduction in the portion sizes of commercially available foods consumed by children (20). Development and provision of standardized information on nutrition labels for age-appropriate servings based on nutritional needs at different ages would allow parents and caregivers to compare food items and help them to make informed decisions about what to feed their children. Similarly, limiting the amount of commercially available food that can be marketed and sold as a single serving and offering price incentives in the form of reduced pricing for smaller packages or serving sizes could have an impact on the portions purchased by parents, as well as older children who purchase some food for themselves and may be less likely to consider the nutrition information on food labels.

While more research is needed, the current evidence suggests that limiting portion sizes reduces overall energy intake and may therefore reduce the risk of unhealthy weight gain. In particular, data from low- and middle-income countries is lacking. As inexpensive, commercially available food becomes increasingly available worldwide (21), it remains unclear what impact marketing of this food in larger serving sizes will have on the eating behaviour of children from low- and middle-income countries.

In summary, establishing and sustaining healthy eating practices from an early age that focus on smaller portions of nutritious, non-energy-dense foods may form an important part of a comprehensive approach to reduce the risk of childhood overweight and obesity.

References

1. United Nations Children’s Fund, World Health Organization, The World Bank. UNICEF-WHO-World Bank Joint Child Nutrition Estimates (UNICEF, New York; WHO, Geneva; The World Bank, Washington DC; 2012).

2. Han JC, Lawlor DA, Kimm SY. Childhood obesity. Lancet. 2010; 375(9727):1737-48.

3. Bjorge T, Engeland A, Tverdal A, Smith GD. Body mass index in adolescence in relation to cause-specific mortality: a follow-up of 230,000 Norwegian adolescents. American Journal of Epidemiology. 2008; 168(1):30–7.

4. Owen CG, Whincup PH, Orfei L, Chou QA, Rudnicka AR, Wathern AK et al. Is body mass index before middle age related to coronary heart disease risk in later life? Evidence from observational studies. International Journal of Obesity (London). 2009; 33(8):866–77.

5. Piernas C, Popkin BM. Food portion patterns and trends among U.S. children and the relationship to total eating occasion size, 1977-2006. Journal of Nutrition, 2011; 141(6):1159-64.

6. Ledikwe JH, Ello-Martin JA, Rolls BJ. Portion sizes and the obesity epidemic. Journal of Nutrition. 2005; 135(4):905-9.

7. Rolls BJ, Engell D, Birch LL. Serving portion size influences 5-year-old but not 3-year-old children's food intakes. J Am Diet Assoc. 2000; 100(2):232-4.

8. Orlet Fisher J, Rolls BJ, Birch LL. Children's bite size and intake of an entrée are greater with large portions than with age-appropriate or self-selected portions. American Journal of Clinical Nutrition. 2003; 77(5):1164-70.

9. Ello-Martin JA, Ledikwe JH, Rolls BJ. The influence of food portion size and energy density on energy intake: implications for weight management. American Journal of Clinical Nutrition. 2005; 82(1 Suppl):236S-241S.

10. Fisher JO. Effects of age on children's intake of large and self-selected food portions. Obesity (Silver Spring). 2007; 15(2):403-12.

11. Fisher JO, Arreola A, Birch LL, Rolls BJ. Portion size effects on daily energy intake in low-income Hispanic and African American children and their mothers. American Journal of Clinical Nutrition. 2007; 86(6):1709-16.

12. Fisher JO, Liu Y, Birch LL, Rolls BJ. Effects of portion size and energy density on young children's intake at a meal. American Journal of Clinical Nutrition. 2007; 86(1):174-9.

13. Looney SM, Raynor HA. Journal of the American Dietetic Association. Impact of portion size and energy density on snack intake in preschool-aged children. 2011; 111(3):414-8.

14. Bish B, Regis K, Gottesman MM. Educating parents about portion sizes for preschoolers. Journal of Pediatric Health Care. 2005; 19(1):54-9.

15. Croker H, Sweetman C, Cooke L. Mothers' views on portion sizes for children. Journal of Human Nutrition and Dietetics. 2009; 22(5):437-43.

16. Steenhuis IH, Vermeer WM. Portion size: review and framework for interventions. International Journal of Behavioral Nutrition and Physical Activity. 2009; 6:58.

17. Savage JS, Haisfield L, Fisher JO, Marini M, Birch LL. Do children eat less at meals when allowed to serve themselves? American Journal of Clinical Nutrition. 2012; 96(1):36-43.

18. DiSantis KI, Birch LL, Davey A, Serrano EL, Zhang J, Bruton Y, Fisher JO. Plate size and children's appetite: effects of larger dishware on self-served portions and intake. Pediatrics. 2013; 131(5):e1451-8.

19. Fisher JO, Birch LL, Zhang J, Grusak MA, Hughes SO. External influences on children's self-served portions at meals. International Journal of Obesity (London). 2013; 37(7):954-60.

20. Young LR, Nestle M. Reducing portion sizes to prevent obesity: a call to action. American Journal of Preventive Medicine. 2012; 43(5):565-8.

21. Popkin BM, Adair LS, Ng SW. Global nutrition transition and the pandemic of obesity in developing countries. Nutrition Reviews. 2012; 70(1):3-21.