Obesity, systems and complexity.

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Obesity, systems and complexity
Harry Rutter
@harryrutter
Evidence trajectories
Time
Hunch-based
Level of activity
Evidence-based
All possible interventions
Evidence of cost-effectiveness
Evidence of effectiveness
The dangerous olive of evidence…
Source: Swinburn et al, Lancet 2011
+ research difficulty

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Obesity strategy analysis
Source: Johnston, Matteson, Finegood, Simon Fraser University: personal communication

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Geoffrey Rose
Change in the adult BMI distribution
Health Survey for England 1991 to 1993 and 2011 to 2013
Adults aged 18+ population weighted

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http://en.wikipedia.org/wiki/File:Colosseum_in_Rome,_Italy_-_April_2007.jpg
2014 Surgeon General’s Report, Fig 2.1. Thanks to Cliff Douglas @cdoug

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Source: Swinburn et al, Lancet 2011
Evidence base
Public/media/political discourse
Political mandate
Source: Swinburn et al, Lancet 2011
Evidence base
Public/media/political discourse
Political mandate
Conclusions
• Don’t treat complex systems as simple: of course many
things appear not to 'work’, we're judging them on the
wrong criteria
• Linear cause and effect is (relatively) easy to look for, but
that doesn’t mean it’s always helpful to do so
• Shift from reductionist, linear, single perspective thinking to
transdisciplinary, non-linear systems thinking
• Don’t forget the lessons of Rose: population level prevention
involves shifting the population curve in ways that may be
indiscernible at individual level
• Conceptualise actions as driving perturbations within
systems, not as hammers applied to nails
• Move from ‘does it work?’ to ‘does it contribute?’