The findings of Alessandro Bartolomucci and collaborators (1) are really interesting and open a wide avenue of new hypothesis for the overwhelming obesity epidemic of our time. A lot of environmental changes of the last decades, repeatedly described, are logically and easily related to the increasing obesity prevalence. However, the dimensions of the phenomenon suggest that, beyond abundant energy dense food and sedentarism, less obvious factors are involved. Stress and disruption of circadian rhythmicity are being given attention. But the results of Bartolomucci et al with individually caged mice are absolutely new and inspiring: under normal chow diet these animals eat less and loose weight, but given access to a high fat diet they eat more and become obese, i.e., they exhibit an increased hedonic response (1).
We wonder if these individually caged mice could be a model of individualism, social isolation, and weak bonding societal conditions in present human societies. At least for children, and for the strange case of children obesity, this seems a forceful hypothesis, deserving consideration. Healthy children used to present a lack of interest in food, complaining when forced to abandon playing to attend the family meal. What is going on with these present day children that do not like to play outdoor games, and prefer instead being seated with palatable food at hand?
Will it be bonding problems, with mothers going back to work when their babies are only a few months old? With parents returning home late and too tired with no time for children? Perturbations of bonding create vulnerability to addiction behaviour (see 2). Another possibility is the putative effect of an egotistic attitude in children favoured by an indulging behaviour of parents that put no resistance to children wishes, don't teach them to respect and care for the other, and don't even allow them the oportunity to dream and/or aim at anything. Research work on these hypothesis could help to improve mental and physical health of next generations.

Laura Ribeiro, Diogo Pestana and Isabel Azevedo
Department of Biochemistry, Faculty of Medicine, University of Porto
4200-319 Porto, Portugal

References

1. Bartolomucci A, Cabassi A, Govoni P, et al (2009) Metabolic Consequences and Vulnerability to Diet-Induced Obesity in Male Mice under Chronic Social Stress. PLoS ONE. 4:e4331.

2. Henry JP (1997) Psychological and physiological responses to stress: The right hemisphere and the hypothalamo-pituitary-adrenal axis, an inquiry into problems of human bonding. Acta Physiol Scand 161, Suppl 640: 10-25.