Thursday, July 2, 2015

Rising food calories driving the 'obesity epidemic'

Scimex: The amount of energy we get from food has risen since 1971 and this is more than enough to explain the increase in average body weight in New Zealand and similar high-income countries, according to a new Kiwi-led study. The authors say that one major factor contributing to the 'obesity epidemic' is the sheer quantity of palatable, ultra-processed food products available, leading to us subconsciously overeating on the calories and gaining weight.

University of Auckland researchers have identified increases in the food energy supply in many countries as a likely driver of increasing obesity – a global health problem.

In a study published today in the Bulletin of the World Health Organization, lead author Dr Stefanie Vandevijvere from the School of Population Health at the University, analysed increases in the food energy supply and obesity in 69 countries.

The research found that both body weight and food energy supply had increased in 56 (81 percent) of the countries surveyed, between 1971 and 2010. In 45 (65 percent) countries, which were mostly high-income countries like New Zealand, the increase in food energy supply was more than enough to explain the increases in average body weight.

"Our study shows that oversupply of calories is a likely driver of overconsumption of those calories and can readily explain the weight gain seen in most countries," says Dr Vandevijvere.

"Overeating to gain weight is not usually a conscious individual decision and many aspects of the food environment influence our diet. One of these is likely to be the sheer quantity of palatable, ultra-processed food products available in the food supply," she says. "It creates a kind of 'push effect' on our diet and we tend to subconsciously overeat on the calories and gain weight."

The study is important because it provides more evidence that governments need to develop the right policies to reduce obesity, which is a risk factor for many health problems, including diabetes, heart disease, stroke and some cancers, she says.

The World Health Organisation's (WHO) 194 Member States agreed on a Global Action Plan for the Prevention and Control of Noncommunicable Diseases at the World Health Assembly in May 2013.  One of the plan's nine voluntary targets is to "halt the rise in diabetes and obesity". It also proposes measures that countries can take to tackle obesity, including restriction of the marketing of unhealthy foods to children, food pricing strategies such as taxes on unhealthy foods, and improving the nutritional quality of foods in schools and other public sector settings.

Dr Vandevijvere and her colleagues compared data on food energy supply and average adult body weight in the 69 countries from the United Nations Food and Agriculture Organization (FAO) database and several databases on average adult weight, including the World Health Organization (WHO) global database on BMI, from two periods of time between 1971 and 2010.

The FAO estimates the food supply of countries by balancing local production, country-wide stocks and imports with their exports, agricultural use for livestock, seed and some components of waste. Waste on the farm, during distribution and processing, as well as losses due to transformation of primary commodities into processed products are usually taken into account but not losses of edible food, such as domestic animal feed, plate-waste and other food that is thrown away.

Between 1980 and 2013, the proportion of adults globally who were overweight, (ie those with a body mass index (BMI) of 25 kg/m2 or more), increased from 28.8 percent to 36.9 percent in men, and from 29.8 percent to 38 percent in women. A person with a BMI of 30 or more is considered obese.

"The amount of added energy intake needed to gain weight is surprisingly small. A 100 kJ of energy is about a half a plain biscuit or a mouthful of soft drink, yet if that energy intake is sustained it will result in an extra kg in weight. Some of the countries in the study had much larger increases in food energy supply than could be explained by the average increase in weight of the population. This suggests that an increasing amount of food is wasted and there is some evidence to support that this is the case," says Dr Vandevijvere.