Intended for healthcare professionals


Eating behaviour and obesity

BMJ 2008; 337 doi: (Published 21 October 2008) Cite this as: BMJ 2008;337:a1926
  1. Elizabeth Denney-Wilson, research fellow1,
  2. Karen J Campbell, public health research fellow2
  1. 1Centre for Primary Health Care and Equity, University of NSW, Sydney, NSW 2052, Australia
  2. 2Centre for Physical Activity and Nutrition Research (C-PAN), School of Exercise and Nutrition Sciences, Deakin University, Vic 3125, Australia
  1. e.denney-wilson{at}

    Eating fast and until full trebles the risk

    In the linked study (doi:10.1136/bmj.a2002), Maruyama and colleagues show a significant positive association between two eating behaviours (eating until full and eating quickly) and overweight in a large sample of Japanese adults.1 The study builds on evidence that eating behaviours are important in promoting positive energy balance (taking in more energy than is expended) and may contribute to the current epidemic of obesity. The drive to overconsume energy when it is available is probably an evolutionary imperative; however, until the last decade or so most adults did not have the opportunity to take in enough energy to enable fat to be stored.

    The ideal situation whereby our eating behaviours are controlled by biological regulatory systems that tightly regulate appetite and consumption and keep our weight in check—is being challenged. We do not know what drives us to eat quickly or to eat until we are full. Have these drivers changed in parallel with the obesity epidemic and are they modifiable? It may be that the changing sociology of food consumption, with fewer families eating together, more people eating while distracted (for example, while watching television), and people eating “fast food” while on the go all promote eating quickly. Furthermore, the increased availability of relatively inexpensive food, which is more energy dense and served in substantially larger portions, may promote eating beyond satiety. Maruyama and colleagues show that the combination of these two factors—eating quickly and eating until full—are additive (odds ratio for being overweight and having both eating behaviours compared with having neither 3.13 (95% confidence interval 2.20 to 4.45) for men and 3.21 (2.41 to 4.29) for women).

    Experimental studies show that humans are relatively ineffective at regulating energy intake.2 For example we rely on visual cues (such as the amount of food that has been removed from a plate) more than the internal cues of fullness3; the volume of food eaten is not modified in response to increased energy density; food consumption increases with variety offered; and the volume eaten is predicted by volume served.

    The effect of the changing food environment on children in particular is likely to be challenging for the future health of the population. As with adults, there is little evidence of short term energy regulation in the face of changing environmental stimuli,4 and the capacity for regulation seems to decrease as children age.5 A study of preschool children found that the strongest correlate of the amount of food consumed at a meal was the amount served, and that the amount consumed was not influenced by energy consumed as snacks between meals.

    Furthermore, a study in preschool children reported that 85% of parents encouraged children to eat more than they may have wanted, and that the same proportion then did, with 38% eating substantially more.6 It seems likely that any early capacity for energy regulation may be over-ridden by parental pressure to eat more.7

    Clinicians should recognise that behavioural counselling, using cognitive therapy, can help in the management of this aggressively “eat more” food environment. Evidence suggests that adults can successfully modify their speed of eating and in turn their energy intake.8 9 Furthermore, adults are likely to be responsive to monitoring feedback regarding feelings of fullness. Helping patients to increase their daily physical activity will further reduce energy imbalance.

    Given the fundamental importance of preventing overweight, clinicians need to engage with parents. Evidence shows that parents can be supported to make effective changes to their children’s eating habits,10 and that young children can be taught to recognise internal cues and alter consumption accordingly.11 Clinicians should encourage parents to adopt a child led feeding strategy that acknowledges a child’s desire to stop eating that begins from birth. Reassure parents that well children don’t starve. Furthermore, because children find it difficult to regulate their energy intake, it is important to inform parents of the environmental stimuli that promote positive energy balance such as serving excessively large meals.

    Discussion about replacing energy dense snack foods and drinks with core foods and water, appropriate serving sizes and body weight, what comprises a healthy diet, eating in non-distracting environments, eating together with an adult, and role modelling with slow and relaxed eating is likely to be useful.


    Cite this as: BMJ 2008;337:a1926



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