I read with interest the interview with Dr John Schoonbee (Changing world health, August 2017), particularly the section regarding dietary guidelines and the concept that dietary fat is not the reason for increasing rates of obesity and diabetes.
I read with interest the interview with Dr John Schoonbee (Changing world health, August 2017), particularly the section regarding dietary guidelines and the concept that dietary fat is not the reason for increasing rates of obesity and diabetes.
The evidence on the link between dietary fat and subsequent disease came from the Seven Countries Study (Keys, A), first published in the late 1970s with regular updates. This study attracted criticism on its methodology from an early stage, leading many to question the validity of the dietary fat/obesity link, resulting in the counter argument that dietary carbohydrate plays a much larger role.
We have indeed witnessed a nutrition transition as a result of urbanisation and food industry marketing; the per capita food consumption in kcal per person per day has increased in all regions of the world since 1969 (Kearney, 2010), alongside an overall global increase in refined sugar intake.
But we cannot have a meaningful debate on the drivers of obesity without considering the physical activity transition. Physical activity is important for the prevention of chronic disease morbidity and mortality; there is a positive association between sedentary time and markers of metabolic risk in young people (The Sedentary Behaviour and Obesity Expert Working Group, 2010). Today's working and leisure time environments actively promote greater sedentary behaviour, with sedentary behaviour and TV viewing at a young age being predictive of becoming overweight as a young adult.
Dr Schoonbee's interview highlighted the lack of clear evidence on nutritional guidelines. What is needed is an untangling of the association between diet, activity and disease with an open, clear mind.
Nicola Oliver
18 August 2017
