May 1, 2019

expert reaction to conference poster looking at rice and obesity

Research presented at the European Congress on Obesity states that an extra quarter cup of rice per person per day may be enough to lower worldwide obesity levels by 1%.

Dr Gunter Kuhnle, Associate Professor in Nutrition and Health, University of Reading, said:

“This is an interesting study but it simply looks at two things and assumes they are linked – we just can’t know from this whether either thing causes the other.

“The study uses high quality data from the UN and FAO, and conducts analysis using a standard approach – and shows that the population in countries with high rice intake have lower obesity rates than countries with low intake.  Although the authors adjust for a number of confounders, it is important to note that the study compares countries and not individuals, and that even after adjustment for factors such as GDP, the observed association is mainly driven by mainly Asian countries with low GDP per caput.  It is therefore very questionable whether these findings can be extrapolated to other populations.  It looks from the figures that the association is mostly driven by a small number of countries and is not universally true – it looks like this relationship might not apply outside Asia.

“White rice consists mainly of carbohydrates, and there is no reason to assume that carbohydrates from rice – and not other sources such as grains or potatoes – have a different effect on obesity.  It is also important to note that white rice contains very small amounts of micronutrients or fibre when compared with other staple foods.  It is therefore very likely that rice intake in this context is simply a surrogate marker for other factors that affect obesity rates.”

Dr Katarina Kos, Senior Lecturer in Diabetes and Obesity, University of Exeter, said:

“This study makes an interesting observation that people in countries with larger rice supplies have a lower BMI, which takes into account earnings and smoking.  It is based on the definition of obesity at BMI above 30.  The study is however not able to tell us whether this ‘lower BMI’ is healthier.  We need not forget that ethnicity plays a big part in developing complications from obesity such as diabetes.  The threshold is much lower for people in Asia which is reflected in the assessment of diabetes and cardiovascular risk by the International Diabetes Federation.  Several organisations would now refer to obesity in China and Japan at a BMI of 28 and above and for India, 27 and above.  These are countries with high rice consumption.  So we shouldn’t get side-tracked by looking at just BMI – we also need to consider that certain populations and ethnicities have relatively higher body fat content for any given BMI as well as unhealthier fat distribution, and how metabolic health relates to rice consumption we just don’t know.”

Abstract title: ‘Rice supply and prevalence of obesity – an international comparative study’ by Imai, T. et al.  This is a conference poster that was discussed at the European Congress on Obesity in Glasgow. There is no paper as this is not published work.

Declared interests

Dr Katarina Kos: “I have no conflict of interest.”

None other received.