Metabolic Waste: An Overlooked Contributor to Climate Change

"Metabolic waste" is a term for the part of what we eat that exceeds our energy needs. Or in other words: the food we don't need and which leads to obesity and a lot of other misery. According to an article 1) published in the scientific journal Obesity 2020, metabolic waste accounts for approximately one point six percent of total greenhouse gas emissions. That's almost as much as all the world's air travel combined. I will return to that comparison.

No unequivocal answers

Canadian medical journalist Julia Belluz recently reported in the New York Times 2) about a meeting at the prestigious Royal Society in London. A qualified group of international scientists from various disciplines had gathered to discuss the causes of the galloping increase in obesity. The explanations ranged from ultra-processed food to microplastics, from fast carbohydrates and gut bacteria to fertilizers and pesticides. One researcher presented the so-called hunger-obesity paradox based on studies showing that birds that receive insufficient energy can still gain weight. From there, she concluded that a similar mechanism might exist in us humans. And then, there was some talk about the importance of genetics and various diseases for our metabolism. But although the scientists agreed on a lot, it was clear that they could not give a clear answer to the question of what makes us fat.

Stone Age brains meet an abundance.

The strange thing about the global obesity epidemic is that it took off in the 80s. Compared to then, more than twice as many adults are overweight or obese today. So what has changed in the forty years since CNN began broadcasting and Post-it notes and the Rubik's Cube saw the light of day? After all, humanity has hardly changed genetically in any decisive way. On the contrary, research has found that our brains function essentially the same way they did in the Stone Age when it was a matter of survival to eat as much as possible on rare occasions when food was plentiful.

And that is probably the explanation or part of it. Stone Age brains were not adapted to the abundance of energy-rich food and drink available to the vast majority of us today. Sugar and fast carbohydrates are cheap energy, and our brains tell us it's best to grab them while we have the chance.

Blame yourself?

And this is where I find the comparison with air traffic so interesting. Because while aviation's one point nine percent share 3) of total greenhouse gas emissions causes heads of government to meet, the EU to establish strict emission laws, Sweden to introduce a special aviation tax, and the aviation industry to develop electric engines, no corresponding demands are placed on the industry behind the waste in metabolism. Instead, the responsibility is placed entirely on the individual, who should also ideally be ashamed of the extra kilos.

And, of course, we have a personal responsibility for what we eat and how much we fly. But suppose we are to address the eating habits that harm our climate and lead to great individual suffering, skyrocketing health care costs, and premature death. In that case, it is time to take a systems perspective on obesity.

Food is politics!

Food and the problems it causes need to be raised to a political level. There is a need for clear game rules that favor health and reduce climate impact. I am doubtful about sticks in the form of sugar taxes and other things that have been tried with varying results. On the other hand, it is entirely in the power of politics to create incentives that can make the food industry go in the right direction. An excellent carrot could be the meals served in public. In the EU, these account for a staggering 83 billion Euros in annual costs. Imagine if wise politicians in Brussels and Strasbourg could decide that (to begin with) ten percent of the meals served in public establishments around Europe must be both climate-smart and healthy and direct procurement accordingly.

I promise that there will be momentum in the industry.

1)The environmental foodprint of obesity Obesity Research Journal 2020

2)Scientists do not agree on what causes obesity, but they know what doesn′t New York Times 2022, behind paywall

3)Climate change and flying: what share of global CO2 emissions come from aviation? Our World in Data 2020

Author: Elin ?stman