The physiology of nutrition is a very interesting subject. Understanding the effects foods has on the physiology of the individual can allow some useful information to be generated regarding improving people’s lives through better health. However, it should always be remembered that humans have interesting behavioural quirks that can alter or even negate completely the expected physiological responses to normal eating. This alteration occurs because behaviour modifies the original expected input and replaces it with something undefined. These behavioural aspects of nutrition are actually much more pertinent than is often thought because humans are driven by their behaviours and often this behaviour is not rational. This makes predicting outcomes from human experiments troublesome for science, and explain why so much controversy still exists within the context of nutritional matters that appear relatively simple on the surface, but highly complex because they are modified significantly by human behaviour.
Behavioural aspect of nutrition can have a significant effect on physiological responses. Observing someone eat for example, reduces the amount of energy they consume. This decreasing the risk of nutrient overload and the risk of obesity.
For example, the act of watching someone eat may significantly alter their energy intake. In a recent study, researchers set out to understand the effects of observation on the energy intake. To do this they analysed the previous data that had been published on the subject in a meta analysis. The results of this analysis showed that evidence of observation by subject involved in laboratory eating significantly reduced the intake of energy compared with control conditions when the subjects were not observed. The authors suggested that laboratory studies should take this into account if they are planning on using laboratory based energy estimates in their study design by minimising the degree to which subject think they are being observed. This is a great example of behaviour altering an expected physiological response, and just one of many that is found in normal free living individuals. Restraint during eating is much more likely when others are present due to the social aspects of peer interaction and social conditioning.
People eat less in a social setting when being observed. It would be interesting to explore how being observed affected the quality of the food intake.
Many eating disorders are kept secret by their sufferers, even from their own families, with bulimia being a cogent example. Restraint by bulimics occurs when presented with the social constructs of an eating environment surrounded by others. It is often only when in isolation that bulimics will indulge in eating binges that they are characterised by. Those who are attempting to lose body fat and improve their body composition are also much less likely to overeat in the presence of others based on the social stigma of being seen to break the bounds of their diet. Even normal weight individuals are likely to show restraint at buffet and other similar social eating events due to the social stigma associated with being labelled greedy. So it is not surprising that research supports the anecdotal evidence in that when observed by others, energy intake falls, and when unobserved it rises significantly. The breakup of family eating time and the emergence of solitary eating may therefore be contributing to obesity more than is thought.
RdB
