Bigger people will do better in a smaller world on grains & veggies
GOETTINGEN, Germany––Better-fed people get bigger.
This trend has been evident in paleontology since our omnivorous but mostly plant-eating Cro-Magnon ancestors circa 40,000 years ago gradually reduced our much older, shorter, and mostly carnivorous Neanderthal cousins to a handful of recessive genetic traits buried deep in the DNA of blue-eyed, fair-skinned blonds.
Better-fed people getting bigger in our own time could either markedly accelerate an ecologically necessary transition from meat-centered to plant-centered diet, or slow worldwide progress toward ending chronic hunger.
10.9 billion people to feed by 2100
The recently published 2019 revision of the United Nations study World Population Prospects, the 26th edition since 1950, found that “The world’s population continues to grow, albeit at a slower pace than at any time since 1950, owing to reduced levels of fertility.”
That was the good news.
The bad news:
“From an estimated 7.7 billion people worldwide in 2019,” the authors projected, “the global population could grow to around 8.5 billion in 2030, 9.7 billion in 2050, and 10.9 billion in 2100.”
Feeding that many people is among the critical challenges ahead for humanity.
United Nations projection of food needs may be 19% low
At that, though, University of Goettingen economists Lutz Depenbusch and Stephan Klasen argue in their paper “The effect of bigger human bodies on the future global calorie requirements,” published on December 4, 2019 by the online Public Library of Science journal PLOS ONE, that the United Nations projection of human food needs may be as much as 19% low.
Simply put, as we become better-fed, we grow, and as we grow, our appetites grow too––even if we become much more sedentary than Neanderthals.
Neanderthals apparently expended about twice as many calories per day, on average, as modern humans, but perhaps half of those calories were burned just to stay warm in the late Pleistocene ice age climate.
“Existing studies show how population growth and rising incomes will cause a massive increase in the future global demand for food,” opened Klasen and Depenbusch, who is also associated with the World Vegetable Center agricultural research institute in Bangkok, Thailand.
“Energy requirements for maintenance of weight”
“We add to the literature,” Depenbusch and Klasen explained, “by estimating the potential effect of increases in human weight, caused by rising body mass index and height, on future calorie requirements.”
Traditional studies of food consumption use a “market-based” approach, which looks at food consumption relative to what farmers can raise and people can buy.
Depenbusch and Klasen went in a different direction, building into their work the assumption that global affluence will continue to rise, enabling more people to eat what they choose to eat––albeit that this privilege will be skewed toward the most affluent, while the poorest and hungriest people may have little or no food choices.
“Instead of using a market based approach,” Depenbusch and Klasen said, their “estimations are solely based on human energy requirements for maintenance of weight.”
Bigger butts = more than combined food needs of India & Nigeria
This means, Depenbusch and Klasen continued, that “In a world where the weight per age-sex group would stay stable, we project calorie requirements to increases by 61.05 percent between 2010 and 2100. Increases in body mass index and height could add another 18.73 percentage points to this.
“This additional increase amounts to more than the combined calorie requirements of India and Nigeria in 2010.
“These increases would particularly affect Sub-Saharan African countries,” Depenbusch and Klasen projected, “which will already face massively rising calorie requirements due to high population growth.
“The stark regional differences,” Depenbusch and Klasen recommended, “call for policies that increase food access in currently economically weak regions. Such policies should shift consumption away from energy dense foods,” specifically protein derived from animal rather than plant sources.
821 million people were underfed in 2017
Further pointing toward the necessity of moving toward plant-based diets, Depenbusch and Klasen noted, “Global agricultural production needs to increase on average by 1.1% per year” between now and 2050, “to meet increasing demand.”
However, Depenbusch and Klasen summarized, other studies indicate that meeting rising demand just by proportionally increasing production of the foods currently eaten “would cause irreversible environmental damage.
“Just looking at calories,” Depenbusch and Klasen continued, “it is well understood that current food supplies would be sufficient to feed the world population,” if grain and legume production in particular were used mostly to feed humans, rather than for feeding livestock, at a huge net loss of protein input when humans eat meat and dairy products.
“However, an estimated 821 million persons [worldwide] were undernourished in 2017,” reminded Depenbusch and Klasen.
Nutritionally poor foods
“Food insecurity is not only coexisting with overweight and obesity,” Depenbusch and Klasen alleged, “but is contributing to it. Particularly in low- and middle-income countries, urbanization and low relative prices for energy-dense but nutritionally poor foods promote the nutrition transition towards high intakes of vegetable oils, caloric sweeteners, processed grains, and animal-sourced foods, that alongside reduced physical activity have been named as ultimate causes of the obesity pandemic.
“If adults in all countries had the same body mass index distribution as the U.S. population,” Depenbusch and Klasen observed, “the increase in energy requirements would be comparable to the requirements of 473 million adults of global average body mass index in 2005. Yet, popular forecasts and policy models of global food demand do not incorporate this effect.
“We do not estimate what would be necessary to supply enough calories to every person to reach a healthy weight,” Depenbusch and Klasen emphasized. “Instead we take into account the existing trend towards greater weight, which in many countries has moved far beyond healthy levels.”
Tacos & beer
Depenbusch and Klasen assumed in their projects that people worldwide would increase in body mass index “at the same speed as Mexico [between 1975 and 2014] and increase height at the Dutch speed,” if nutrition permits, “until reaching the body mass index of Mexico and the height of Dutch in 2010. We use back-casting techniques to validate our assumptions.”
Reiterated Depenbusch and Klasen, “Our estimates are about required calories for a diet that maintains the weight of everyone in the world.
“This is a normative concept that might bear little relation with the current actual availability of calories for human consumption.”
Inequality of access to food, Depenbusch and Klasen recognized, is a greater challenge in eradicating hunger and malnutrition than simply producing enough food.
Only nine nations produce fewer calories than they need
“According to our estimates only nine countries did not have as many calories available as required,” Depenbusch and Klasen said.
“A larger concern are the future needs for food production and distribution necessary to ensure food security for all. Energy requirements are only one factor affecting food demand, though. Three other distinctive factors will have a major role,” Depenbusch and Klasen warned.
“First, a considerable share of food is lost or wasted. Agricultural production would therefore need to produce additional calories to make up for the losses.
“Second, consumption of meat and dairy products acts as a multiplier on demand, as producing these goods needs additional energy in the form of feeds. Predictions on future demand for meat foresee slower growth rates,” Depenbusch and Klasen acknowledged, “around 1.3 percent per annum,” between now and 2050, “not least because many countries already reached fairly high meat consumption levels.
Bigger people eating more animal foods = starvation
“It is unclear how exactly increased calorie consumption due to rising weights would affect the demand for meat and dairy products,” Depenbusch and Klasen said. “One indication is that protein requirements rise with the amount of lean tissue in a body,” which will increase as humans grow taller.
“If meat and dairy products are used to cover this requirement,” Depenbusch and Klasen cautioned, “weight increases will raise the demand for meat and dairy products.
“Third, inequalities in distribution will increase the amount of food needed to ensure zero hunger.
“Rising human weights will have a sizable effect on what people most likely [will want] to eat,” explained Depenbusch and Klasen from their perspective as economists.
Guns or butter?
“In economic terms this relates to a higher preference for food compared to other goods,” in other words more people choosing to eat butter rather than to buy guns.
“This would translate to an upward shift in the demand for food and ultimately an increase in food prices at any given level of supply. This puts an even heavier burden on countries that will already have trouble meeting requirements, irrespective of this factor.
Depenbusch and Klasen became more emphatic about the importance of reducing animal product consumption in their conclusion.
“Relative prices need to discourage the over-consumption of energy-dense foods associated with rising body mass index,” Depenbusch and Klasen wrote. “The primary focus needs to be on ensuring affordable prices of products like vegetables, fruits, pulses [lentils], and coarse grains that are rich in nutrients and put less pressure on the environment.
Downsizing people is not the answer
“One may also argue,” Depenbusch and Klasen finished, “that in those countries that are unable to secure enough calories to feed their growing populations, [people] not gaining weight or increasing height will be one of the responses to partly address this problem. But such adjustments are rarely smooth and equitable. A more likely scenario would be that this would be accompanied by starvation for many, often affecting the most vulnerable groups the most.”
The Depenbusch and Klasen paper “The effect of bigger human bodies on the future global calorie requirements” appeared eight days ahead of a letter to the Lancet Planetary Health journal, signed by more than 50 leading scientists, arguing that “Countries should be looking for peak livestock within the next 10 years, because we need steep and rapid reductions in greenhouse gas emissions, as we are reaching dangerous temperature tipping points.”
“As a planet, we need to transition away from livestock”
Among those joining Harvard Law School fellow and lead author Helen Harwatt as a co-author was University of Aberdeen professor Pete Smith, a senior author of the Intergovernmental Panel on Climate Change report on land use and climate change, published in August 2019.
“Ruminant meat is 10 to 100 times more damaging to the climate than plant-based food,” Smith told Guardian environment editor Damian Carrington. “As a planet, we need to transition away from a dependence on livestock,” Smith said, “just as we need to to transition away from fossil fuels. Livestock numbers need to peak very soon, and thereafter decline substantially.
“But the transition will need to be managed fairly,” Smith added, “to allow citizens to change diets and for farmers, producers and agri-food chains to diversify. In poor countries, where over 800 million people are still undernourished, priorities obviously differ.”
Wrote Carrington, “Of the world’s mammals, 60% by weight are livestock, 36% are humans, and only 4% are wild mammals, according to 2018 research by professor Ron Milo, at the Weizmann Institute of Science in Israel, who also backed the letter.
“More than 80% of farmland [worldwide] is used for livestock but it produces just 18% of food calories,” even after global production of meat, milk, and eggs nearly doubled from 758 million metric tons in 1990 to 1,247 million metric tons in 2017, Carrington concluded.