Abstract
Changes in national and global food demand are commonly explained by population growth, dietary shifts, and food waste. Although nutrition sciences demonstrate that biophysical characteristics determine food requirements in individuals, and medical and demographic studies provide evidence for large shifts in height, weight, and age structure worldwide, the aggregated effects for food demand are poorly understood. Here, a type–cohort–time stock model is applied to analyze the combined effect of biophysical and demographic changes in the adult population of 186 countries between 1975–2014. The average global adult in 2014 was 14% heavier, 1.3% taller, 6.2% older, and had a 6.1% higher energy demand than the average adult in 1975. Across countries, individuals’ weight gains ranged between 6–33%, and energy needs increased between 0.9–16%. Noteworthy, some of the highest and lowest increases coexist within Africa and Asia, signaling the disparities between the countries of these regions. Globally, food energy increased by 129% during the studied period. Population growth contributed with 116%; weight and height gains accounted for 15%; meanwhile, the aging phenomenon counteracted the rise in energy needs by −2%. This net additional 13% demand corresponded to the needs of 286 million adults. Since the effect of biodemographic changes are cumulative, we can expect the observed inertia to extend into the future. This work shows that considering the evolving individual biophysical characteristics jointly with sociodemographic changes can contribute to more robust global resource and food security assessments. Commonly used static and homogenous caloric demand values per capita might lead to misrepresentations of actual needs. What previous analyses could have estimated as increased food availability, sufficiency, or surplus waste might actually be energy sequestered by the mass of the human lot. Based on the discovered trends, feeding nine billion people in 2050 will require significantly more total calories than feeding the same people today.
Highlights
Human activity is regarded as the dominant cause of contemporary environmental change, driven by the resources required by populations [1,2,3,4,5]
In the past four decades, the population increased by 116%, but was outpaced by increases of 146% in human mass and 129% in total theoretical food energy requirements (Figure 2a)
The results presented here depict the relevance of considering both weight and demographic structural changes when accounting for food energy, and demonstrate that changes in height and BMI have a larger impact than demographics (Figure 4)
Summary
Human activity is regarded as the dominant cause of contemporary environmental change, driven by the resources required by populations [1,2,3,4,5]. The most comprehensive assessments on the human–environment relationship traditionally describe resource use as a function of the population’s size, affluence, and technology [4,6,7,8,9,10,11,12]. Evidence shows that humans changed drastically at the individual and societal levels over the past century. Global life expectancy increased from 36 to 70 years during the 20th century [13]. Adult height increased as much as 20 cm for some nations in only four generations (100 birth cohorts) [14].
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