Dimensions of nutritional responsibility: What is the contribution of the brain? (Dimensionen der Ernährungsverantwortung: Welchen Beitrag leistet das Gehirn?)

Horstmann, A. (Speaker)

Activity: Talk or presentation typesInvited talk


The incidence of overweight and obesity has increased unabated almost everywhere in the world over the last 50 years. However, it is a common misconception that obesity is a result of individual conscious choices and can be reversed by sheer willpower. This fact is reinforced by the classification of obesity as a chronic recurrent disease.
But why exactly is obesity so difficult to control? Does the responsibility lie with the individual or with society? The search for genetic causes has not been very promising so far: although there are monogenetic causes for severe obesity, these are extremely rare. More frequent obesity-associated gene variants have been identified, but explain little variance. Even the analysis of environmental factors alone does not show who becomes overweight and who seems to be immune. A missing link could be epigenetic factors - these alter the reading pattern of the DNA sequence and are influenced by lifestyle characteristics such as diet, stress and physical activity. Lifestyle - in this context primarily individual behaviour - is shaped by ongoing choices. Of particular interest here are decisions that affect energy balance: When and how much is eaten, how and how much is exercised?
Neurocognitive studies show that there are changes in many aspects of decision-making behaviour in people with obesity. Interestingly, even when these decisions are not about eating or exercise. This could be explained by changes in areas of the brain that are fundamentally responsible for the various processes of decision-making. There is supportive evidence from neuroscience: A key neurotransmitter system that contributes significantly to motivation, learning and reward-dependent decision-making shows complex alterations in obesity, both in humans and in animal models. Moreover, diet quality alone, independent of the development of obesity, appears to cause these changes, which then lead to the cognitive changes and reduced physical activity.
So what does this mean for the assumption that obesity is a consequence of conscious choices and can simply be reversed by willpower? In obesity, the basic decision-making machinery of the brain seems to be altered, which is why the environment, with all its temptations, is perceived differently and incentives to change behaviour are evaluated with a different "neuronal measure". Genetics and, in many cases, environmental factors cannot be shaped, or can only be shaped with difficulty. At the societal level, however, the design of the nutritional and living environment offers a starting point for prevention and intervention.
Period23 Jun 2021
Event titleJahrestagung des Deutschen Ethikrates 2021 (Annual Conference of the German Ethics Council 2021): Wohl bekomms! Dimensionen der Ernährungsverantwortung (Cheers! Dimensions of nutritional responsibility)
Event typeConference
LocationBerlin, Germany, Berlin
Degree of RecognitionNational