Boyd Swinburn says it's very easy to become obese in a country like New Zealand. Photo / 123rf
Boyd Swinburn says it's very easy to become obese in a country like New Zealand. Photo / 123rf
In the latest episode of her Chewing the Facts podcast, Sasha Borissenko explores the role of genetics and the ultra-processed food environment.
In 2020, former National Party leader Judith Collins told Newstalk ZB that “people need to start taking some personal responsibility for their weight”.
Unfortunately, it’s not quite that straightforward.
“It can’t simply be explained by the fact that some people choose to go to the gym and others don’t,” explained Otago University neuroendocrine and metabolic professor, Greg Anderson.
“Obviously, some people put on weight because the energy intake exceeds the energy output. That’s the simple answer, but it hasn’t got us anywhere.”
Former National Party leader Judith Collins said people needed to take personal responsibility for their weight. Photo / Mark Mitchell
Speaking in the latest episode of Chewing the Facts, Anderson said some people have a greater basal metabolic rate, which is the energy people burn when they are sitting still, sleeping, and breathing, for example.
Studies show food digestion accounts for 8-15 per cent, metabolic rate can account for 60-80 per cent, and physical activity accounts for just 15-30 per cent.
Specific genes inform the way hormones and metabolism are expressed. Genetic influence varies between 25 and 80 per cent of the factors behind how some people gain weight.
Harvard University research suggests more than 400 different genes contribute to weight, affecting appetite, satiety (the feeling of being full), metabolism, food cravings, and body-fat distribution.
“Free will is not the same for every person. So if we think about what the situation was like maybe 500 years ago, there weren’t supermarkets around, so food was often scarce [...] Most of the people that were contributing to our gene pool lived in this pretty lean environment,” he said.
“We’re just driven to eat [biologically]; we’re wired that way, but some more than others because of these genes.”
World Health Organisation nutrition, health, and development director Francesco Branca told Chewing the Facts the change in food systems had failed to feed people in the right way.
Ultra-processed foods did not contribute to a healthy diet and should be consumed very sparingly, he said.
These are products that are appealing, affordable, easily accessible, heavily marketed, have a long shelf-life, and are high in fat, sugar, and salt.
Branca said the long shelf life undermines the nutritional value of the ingredients and the introduction of additives means they have negative elements but also lack positive elements of the food’s original chemistry.
“Food systems have evolved following other objectives - so, food as commodities, food systems as a source of income, but not to address people’s health and nutrition needs.”
Professor Boyd Swinburn. Photo / NZPA / Tim Hales
Auckland University population nutrition and global health professor Boyd Swinburn coined the term, ‘obesogenic environment’, which describes areas shaped by cheap, convenient, and ultra-processed foods, social and economic pressures, and barriers to exercise.
Boyd said fatness is a typical physiological response to the change of environment over the last 30 years.
If people are exposed to an obesogenic environment, then genetics will determine how much weight gain is expressed, he says.
“It’s very easy to become obese in a country like New Zealand. You just have to eat what’s on offer, eat what’s advertised, what’s freely available, and what’s on special at the supermarket. You become obese, no worries about that at all, it’s easy. It requires quite a lot of effort not to be.”
Chewing the Facts - new episodes out every Sunday. Produced with the NZ Herald, with support from NZ On Air.
