J Health Behav Med Hist 2026-7
Clarifying the Behavioural Systems Perspective on Obesity. Summary of reader comments and author response
Robert C. van de Graaf, Performance Medicine Specialist, Director
MEDTCC Institute for Health, Behaviour, Medicine and its History, and Perform Health Clinic ,The Netherlands
Peter F. van de Graaf, Health Performance Coach
MEDTCC Institute for Health, Behaviour, Medicine and its History, and Perform Health Clinic ,The Netherlands
Several colleagues and readers of the article Reframing obesity: from adipose tissue disease to behavioural system outcome [1] raised thoughtful questions regarding the conceptual framework presented.
These reactions were not unexpected. The behavioural systems perspective proposed in the article shifts the emphasis within obesity research from adipose tissue as the primary explanatory level toward behavioural dynamics generated within a relational behavioural organ system. Conceptual shifts of this kind naturally invite discussion and critical reflection.
Some readers recognised the value of examining behavioural persistence and feedback mechanisms in obesity. Others raised questions about how this perspective relates to established biomedical models of obesity, the role of biological determinants, and the implications for medical treatment.
Three concerns emerged repeatedly in these discussions. These concerns are addressed below in order to clarify the conceptual intent of the behavioural systems perspective.
Concern 1: Does the behavioural systems perspective underestimate biology?
One concern raised by readers is that emphasising behavioural dynamics might underestimate the role of biological determinants in obesity.
Contemporary research clearly demonstrates that body weight regulation is influenced by complex biological mechanisms, including neuroendocrine signalling, appetite regulation, and genetic susceptibility. Hormones such as leptin, ghrelin, insulin, and cortisol influence hunger, satiety, and metabolic balance, while genetic variation may affect appetite regulation, reward sensitivity to food, and metabolic efficiency.
The behavioural systems perspective does not deny these biological mechanisms. Rather, it seeks to clarify how biological signals influence long-term energy balance.
In this framework, biological processes influence behaviour primarily by shaping internal regulatory states within the organism. Signals related to hunger, satiety, fatigue, reward sensitivity, stress responses, and metabolic status affect how individuals experience and regulate eating, activity, sleep, and other health-related behaviours.
Biological determinants therefore remain central. However, their influence on body weight typically operates through behavioural regulation over time.
Instead of opposing biological explanations, the behavioural systems perspective attempts to connect biological mechanisms with behavioural regulation within a single integrative framework.
Concern 2: Is the concept of a “behavioural organ system” sufficiently clear?
A second concern relates to the conceptual clarity of the term behavioural organ system.
In the article, the behavioural organ is not described as a discrete anatomical structure. Instead, it refers to a relational system responsible for designing and executing behaviour through continuous interaction between the organism and its environment.
Within the organism, biological and psychological processes such as perception, emotion, motivation, reward processing, memory, and stress regulation influence internal states that shape behavioural regulation.
At the same time, environmental structures – including physical surroundings, social norms, cultural practices, and institutional arrangements – shape the behavioural possibilities available to individuals.
In this perspective, the environment is not merely an external determinant of behaviour but a constitutive component of the behavioural organ system itself. Behaviour therefore emerges from the dynamic interaction between organism and environment within this relational system.
The concept of the behavioural organ system is therefore intended as a systems-level framework that connects biological regulation, behavioural processes, and environmental context.
Concern 3: Does focusing on behaviour risk blaming individuals?
A third concern raised by readers is that emphasising behaviour might unintentionally revive narratives that place excessive responsibility on individuals.
Historically, lifestyle explanations of obesity have sometimes been associated with stigma or moral judgement. The modern framing of obesity as a chronic disease partly emerged to counter such narratives and to acknowledge the complex biological regulation of body weight.
However, within the behavioural systems framework behaviour is not interpreted as the product of isolated personal choices.
Behaviour emerges from the interaction between biological processes within the organism and environmental structures that shape behavioural possibilities. Modern environments strongly influence behavioural dynamics. Highly palatable foods are widely available and heavily marketed, while digital technologies and modern transportation systems reduce the need for physical activity. Social networks and cultural norms further influence eating patterns, activity levels, and coping behaviour.
These environmental structures form part of the behavioural organ system itself. They shape the behavioural landscape within which individuals operate.
Behaviour in this framework is therefore understood as the output of a relational system shaped by biological predispositions, environmental structures, and learned behavioural patterns, rather than as the result of isolated individual choices.
Toward an integrated perspective
Taken together, these clarifications highlight that the behavioural systems perspective does not seek to replace biological explanations of obesity.
Instead, it attempts to integrate biological regulation, behavioural dynamics, and environmental influences within a single conceptual framework.
Within this framework, biological processes influence internal states within the organism, environmental structures shape behavioural opportunities, and behavioural patterns determine long-term energy balance.
From this perspective, obesity can be understood as a biological outcome of persistent behavioural dynamics generated within behavioural organ systems operating in modern environments.
Importantly, the relationship between behaviour and obesity is bidirectional. Once obesity develops, physiological and psychosocial changes associated with increased adiposity may further influence behavioural regulation.
In this way, obesity becomes part of the same behavioural feedback system that contributed to its development.
Understanding these dynamics may help bridge the gap between biomedical research on metabolic mechanisms and practical strategies for prevention and long-term health improvement.
- Van de Graaf RC, Van de Graaf PF. Reframing obesity: from adipose tissue disease to behavioural system outcome. J Health Behav Med Hist 2026-6.