Topic Summaries

Biological explanations for obesity

A-Level > Psychology > AQA > A-Level Psychology Topic Summaries > Eating behaviour > Biological explanations for obesity
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Addiction

  • Obesity has been linked to both genetic and neural factors.
  • Genetic research has shown a strong heritable component. 👥 Stunkard et al. (1990) found that the heritability of body mass index (BMI) can be as high as 70%, and the FTO gene has been identified as increasing susceptibility to obesity. Such findings explain why obesity runs in families.
    • However, genes alone cannot explain the rapid rise in global obesity, suggesting that environmental factors such as sedentary lifestyles and processed foods also play a major role. Thus, genes may create a predisposition, but do not determine outcomes.
  • Neural explanations highlight the role of hormones such as leptin and ghrelin. Individuals with leptin deficiencies fail to experience satiety and therefore overeat, while persistently high levels of ghrelin can cause ongoing hunger.
  • Research has shown that leptin therapy can reduce obesity in individuals with rare leptin gene mutations (👥 Licinio et al., 2004).
  • The hypothalamus, which regulates hunger and satiety, is also implicated in obesity when functioning abnormally.
    • While these biological findings are robust, they have been criticised as reductionist, because they downplay psychological factors such as stress eating and the influence of external food cues

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