by contrast, recognizes that outcomes are driven by interactions among the components, emphasizing the need to understand these interactions and identify efficacious control points. The second bias, the “complexity bias,” assumes that the interacting agents in complex systems themselves have complicated properties, whereas the complex adaptive systems approach recognizes that the drivers of complex outcomes can in fact be very simple [127]. Together these insights can help to reframe the public health challenge of nutrition transitions by focussing the search for simple properties of interacting agents that might have disproportionate leverage in shaping food systems and directing intervention strategies accordingly.
We believe that the relevant properties of interacting agents that explain nutrition transitions have already been identified. In consumers, the central issue is appetite systems, and how these interact with such factors as palatability, pleasure associations, cost, and convenience. In the broader food environment, the key issue is commercial profitability. The protein leverage hypothesis is a model of how these have come together to drive the obesity epidemic [18,70]. This recasts the debate of individual responsibility vs. social determinants by emphasizing that nutrition transitions are an emergent outcome of dynamic interactions between people and food environments. Interventions and policies that assume individuals and corporations will exercise agency in a direction not aligned with appetite and profit are bound to fail.
Conclusions
The fundamental biological drivers of dietary intake are no different in humans than other species, from insects in laboratory studies to wild primates in natural ecologies. Humans differ, however, in being the only species facing a dietary crisis of its own making. The root cause is that our evolved biological appetites have found expression via cultural means including science, technology, and economics, which have driven transitions towards food environments with which that biology is incompatible. A particularly relevant dimension of this transition is the emergence of corporate agency and its progressive empowerment through transnationalization. Interdisciplinary perspectives are essential for understanding this process and even more so for managing it. There are many productive contact points between the sciences of ecology and public health that can help facilitate progress towards a solution. Ecological perspectives can illuminate human biology through insights from species that are not complicated by the culture‐driven transformations with which humans have become inextricably intertwined. Ecology can also dispel the perception that the engineering prowess that provided the tools on which the food industry and its globalization are predicated is up to the task of managing the nutrition transitions they have facilitated. For that, a different paradigm is needed, which respects that, like any other species, we live in an ecology that assumes emergent properties not inherent in any of the components, whether that be individuals, corporations, or governments. Complexity theory can provide the tools for conceptualizing this situation and the potential for managing it through identifying key control points. Ironically, a complex systems approach might succeed where other approaches have failed by demonstrating the problem is simpler than assumed. Even though humans and corporations are immensely complex systems, the primary drivers of nutrition transitions are deceptively simple: biological appetites for nutrients and the corporate appetite for profit. Protein leverage is a simple model that can illuminate how these appetites have interacted to generate an obesity epidemic. The challenge ahead is to use this information to formulate solutions.
References
1 1. Raubenheimer D, Simpson SJ. Eat Like the Animals: What Nature Teaches us about the Science of Healthy Eating. New York: Houghton Mifflin Harcourt, 2020:256 p.
2 2. Raubenheimer D, Simpson SJ. The geometry of compensatory feeding in the locust. Anim Behav 1993; 45(5):953–64.
3 3. Raubenheimer D, Simpson SJ. Integrative models of nutrient balancing: application to insects and vertebrates. Nutr Res Rev 1997; 10(1):151–79.
4 4. Simpson SJ, Raubenheimer D. The geometric analysis of macronutrient selection in the rat. Appetite 1997; 28(3):201–13.
5 5. Magnusson RS. Obesity prevention and personal responsibility: the case of front‐of‐pack food labelling in Australia. BMC Public Health 2010; 10:662.
6 6. Go JJ. Structure, choice, and responsibility. Ethics Behav 2020; 30(3):230–46.
7 7. Brown RC, Savulescu J. Responsibility in healthcare across time and agents. J Med Ethics 2019; 45(10):636–44.
8 8. Nestle M, Jacobson MF. Halting the obesity epidemic: a public health policy approach. Public Health Rep 2000; 115(1):12–24.
9 9. Lee BY, Bartsch SM, Mui Y, Haidari, LA, Spiker ML, Gittelsohn J. A systems approach to obesity. Nutr Rev 2017; 75(suppl 1):94–106.
10 10. Rubino F, Puhl RM, Cummings DE, et al. Joint international consensus statement for ending stigma of obesity. Nat Med 2020; 26(4):485–97.
11 11. Muttarak, R. Normalization of plus size and the danger of unseen overweight and obesity in England. Obesity 2018; 26(7):1125–9.
12 12. Hruby A, Hu FB. The epidemiology of obesity: a big picture. Pharmacoeconomics 2015; 33(7):673–89.
13 13. Simpson SJ, Raubenheimer D. The Nature of Nutrition: A Unifying Framework from Animal Adaptation to Human Obesity. Princeton: Princeton University Press, 2012:256 p.
14 14. Taubes G. The science of obesity: what do we really know about what makes us fat? An essay by Gary Taubes. BMJ 2013; 346:f1050.
15 15. Morris MA, Wilkins E, Timmins KA, Bryant M, Birkin M, Griffiths C. Can big data solve a big problem? Reporting the obesity data landscape in line with the Foresight obesity system map. Int J Obes 2018; 42(12):1963–76.
16 16. Bagnall AM, Radley D, Jones R, et al. Whole systems approaches to obesity and other complex public health challenges: a systematic review. BMC Public Health 2019; 19(1):8.
17 17. Lambert H, Hakim O, Lanham‐New SA. Major minerals: calcium and magnesium. In: Mann J, Truswell AS (eds) Essentials of Human Nutrition. Oxford: Oxford University Press, 2017:131–40.
18 18. Raubenheimer D, Simpson SJ, Mayntz D. Nutrition, ecology and nutritional ecology: toward an integrated framework. Funct Ecol 2009; 23(1):4–16.
19 19. Raubenheimer D, Simpson SJ. Nutritional ecology and human health. Annu Rev Nutr 2016; 36:603–26.
20 20. Simpson SJ, Raubenheimer D. A multi‐level analysis of feeding behaviour: the geometry of nutritional decisions. Philos Trans R Soc B 1993; 342(1302):381–402.
21 21. Raubenheimer D, Simpson SJ. Nutritional ecology and foraging theory. Curr Opin Insect Sci 2018; 27:38–45.
22 22. Chambers PG, Simpson SJ, Raubenheimer D. Behavioural mechanisms of nutrient balancing in Locusta migratoria nymphs. Anim Behav 1995; 50(6):1513–23.
23 23. Raubenheimer D, Jones SA. Nutritional imbalance in an extreme generalist omnivore: tolerance and recovery through complementary food selection. Anim Behav 2006; 71(6):1253–62.
24 24. Simpson SJ, Sibly RM, Lee KP, Behmer ST, Raubenheimer D. Optimal foraging when regulating intake of multiple nutrients. Anim Behav 2004; 68(6):1299–311.
25 25. Lee KP, Simpson SJ, Clissold FJ, et al. Lifespan and reproduction in Drosophila: new insights from nutritional geometry. Proc Natl Acad Sci U S A 2008; 105(7):2498–503.
26 26. Jensen K, Mayntz D, Tøft S, et al. Optimal foraging for specific nutrients in predatory beetles. Proc R Soc B 2012; 279(1736):2212–8.
27 27.
