Obesity levels are substantially lower in countries that consume high amounts of rice, while counties with lower average rice intake have higher obesity levels, recent findings suggest.

The link between rice intake and obesity persisted even after taking into account other lifestyle and socioeconomic risk factors including total energy consumption, education, smoking, gross domestic product per capita, and health expenditure. The researchers estimate that even a modest increase in average rice consumption could reduce the worldwide prevalence of obesity by 1%.

"The observed associations suggest that the obesity rate is low in countries that eat rice as a staple food. Therefore, Japanese food or an Asian-food-style diet based on rice may help prevent obesity. Given the rising levels of obesity worldwide, eating more rice should be recommended to protect against obesity even in western countries,” said Tomoko Imai, lead researcher of the study discussed in European Congress on Obesity meeting.

People who eat higher levels of dietary fibre and whole grains have lower body weight and cholesterol, and lower rates of non-communicable diseases compared with people with lower intakes. However, the effect of rice consumption on obesity is unclear. To better understand the link between the two, Imai and colleagues examined rice (all rice products including white rice, brown rice, rice flour) relative consumption and energy consumption in the diets of 136 countries with populations of more than 1 million, using data from the UN Food and Agriculture Organization.

These data were analysed together with estimates of obesity prevalence, the average number of years spent in education, percentage of the population over 65 years old, gross domestic product (GDP) per capita, and health expenditure. Countries were categorised into low and high consumption groups.

Their analysis showed that total energy consumed, smoking rates, obesity levels, percentage of population over 65 years old, GDP, education, and health expenditure were significantly lower in countries that consumed high levels of rice, including as Bangladesh (ranked 1st; 473 g/day/person), Lao (2nd; 443) Cambodia (3rd; 438), Vietnam (4th; 398), and Indonesia (5th; 361), compared to countries with lower rice intake including France (ranked 99th; 15 g/day/person), the UK (89th; 19), the USA (87th; 19), Spain (81st ; 22), Canada (77th; 24), Australia (67th; 32).

Even after taking into account and adjusting for these known risk factors, an inverse association was observed between rice consumption and rates of obesity--suggesting that higher intakes of rice could provide even greater protection. According to the researchers, eating rice seems to protect against weight gain. It's possible that the fibre, nutrients, and plant compounds found in whole grains may increase feelings of fullness and prevent overeating.

"Rice is also low in fat and has a relatively low postprandial blood glucose level which suppresses insulin secretion. However, there are also reports that people who overeat rice are more likely to develop metabolic syndrome and diabetes. Therefore, an appropriate amount of rice intake may prevent obesity", said Imai.

Although the research does not establish a cause-and-effect relationship between country-level rice consumption and obesity, the researchers say that it should be investigated further. Whilst a limitation of cross-sectional studies is the risk of identifying false associations as a result of confounding factors, the association identified between rice consumption and obesity remained even after adjusting for various lifestyle and socioeconomic risk factors.