Welcome to the Psychology of Eating Behaviour!

Ever wondered why you suddenly crave a chocolate bar when you're stressed, or why some people are much pickier eaters than others? In this chapter, we explore the fascinating reasons behind how, what, and why we eat. We will look at everything from our ancient ancestors' survival instincts to the complex biological and psychological reasons behind eating disorders and obesity.

Don't worry if some of the biological terms seem a bit "sciencey" at first—we will break them down into simple pieces together!

1. Why do we like what we like? (Food Preferences)

Our food choices aren't just about taste; they are rooted in our evolution and how we've learned to interact with the world.

The Evolutionary Explanation

Our ancestors lived in environments where food was scarce. To survive, they developed preferences that helped them stay alive:

  • High-energy foods: We naturally prefer sweet and fatty foods because they provided the calories needed for survival in the wild.
  • Salt: This is essential for cell function, but it was rare in the past, so we evolved to find it tasty.
  • Neophobia: This literally means "fear of the new." Neophobia is an innate tendency to avoid new or unfamiliar foods. It protected our ancestors from eating something poisonous.
    Analogy: Think of a toddler refusing to try a green vegetable they’ve never seen before—that’s their inner caveman trying to keep them safe!
  • Taste Aversion: If you eat something and get sick afterwards, you’ll likely hate that food for a long time. This is a survival mechanism called Learned Taste Aversion. It helps us avoid toxic substances.

The Role of Learning

While evolution gives us the "basics," our environment shapes the rest:

  • Social Influences: We often copy what our parents, peers, or even celebrities eat (Modelling). If you see your big brother enjoying salad, you’re more likely to try it.
  • Cultural Influences: Our culture determines what is considered "food." For example, some cultures love spicy chillies, while others find them painful. This is usually learned through exposure.

Quick Review:
- Evolution = Survival (Sugar/Fat = Energy).
- Neophobia = Avoiding the unknown (Poison prevention).
- Learning = Copying others and following cultural "rules."

2. The "Hunger Thermostat": Neural and Hormonal Mechanisms

How does your brain know you’re hungry? It’s all about a tiny part of the brain called the Hypothalamus and some very important chemical messengers.

The Hypothalamus

Think of the Hypothalamus as your body’s command centre for eating. There are two main parts you need to know:

  • Lateral Hypothalamus (LH): The "On Switch." When this is stimulated, you feel hungry and start eating.
  • Ventromedial Hypothalamus (VMH): The "Off Switch." When this is stimulated, you feel full and stop eating (satiety).

Hormones: Ghrelin and Leptin

Your brain listens to two main hormones to decide whether to flip the "On" or "Off" switch:

  1. Ghrelin: Released by the stomach when it’s empty. It tells the LH that it’s time to eat.
    Memory Aid: Think of your stomach "Grrr-elin" (growling) when you're hungry!
  2. Leptin: Produced by fat cells. It tells the VMH that you have enough energy stored and should stop eating.

Key Takeaway: Eating is controlled by a delicate balance. If the LH says "Go" and the VMH says "Stop," hormones like Ghrelin and Leptin are the messengers that deliver the news.

3. Explaining Anorexia Nervosa (AN)

Anorexia is a serious mental health condition. Psychologists look at both biological and psychological causes.

Biological Explanations

  • Genetics: Research shows that AN often runs in families, suggesting a genetic vulnerability.
  • Neural: People with AN may have different levels of Serotonin (linked to anxiety and obsessive behaviour) and Dopamine (linked to how we process rewards).

Psychological Explanations

1. Family Systems Theory: This theory suggests that the "problem" isn't just in the individual, but in how the family interacts. Key terms include:

  • Enmeshment: Family members are overly involved in each other’s lives; there are no boundaries.
  • Autonomy and Control: The person with AN may feel they have no control over their life, so they use food as the one thing they can control.

2. Social Learning Theory (SLT): This suggests we learn eating behaviours from our environment.

  • Modelling: Seeing "thin" models in the media.
  • Reinforcement: Getting compliments for losing weight (Positive Reinforcement).

3. Cognitive Theory: Focuses on "faulty" thinking.

  • Distortions: For example, someone with AN looking in a mirror and seeing themselves as "fat" even when they are dangerously underweight.
  • Irrational Beliefs: Thinking "If I’m not perfect/thin, I’m a total failure."

4. Explaining Obesity

Obesity is defined as having excess body fat that may affect health. Like Anorexia, it has both biological and psychological roots.

Biological Explanations

  • Genetics: Some people are genetically predisposed to store fat more easily or have a slower metabolism.
  • Neural: The Dopamine reward system might be less sensitive in some people, meaning they need to eat more to feel the same "pleasure" from food.

Psychological Explanations

1. Restraint Theory: Paradoxically, trying to "restrain" (limit) food intake can actually lead to overeating. When you tell yourself you can't have a cookie, you think about the cookie more!

2. Disinhibition: This is when something "triggers" you to lose your self-control. For example, if you are on a diet but then have a small piece of cake, you might think "I've ruined it now, I might as well eat everything" (also known as the "What the hell" effect).

3. The Boundary Model:
This model suggests we have a physiological "hunger" boundary and a "satiety" (fullness) boundary.
- Restrained eaters (dieters) create a psychological boundary for themselves.
- Once they cross that psychological boundary, they enter a "zone of biological indifference" where they just keep eating until they feel physically stuffed.

Did you know? Research shows that people who constantly diet (restrained eaters) are actually more likely to gain weight over time than those who eat when they are hungry!

Summary and Key Terms Checklist

Make sure you can define and explain these key concepts for your exam:

  • Neophobia (Fear of new foods)
  • Hypothalamus (The LH and VMH switches)
  • Ghrelin (Hunger hormone) and Leptin (Fullness hormone)
  • Enmeshment (Over-involved family dynamics in AN)
  • Cognitive Distortions (Faulty thinking patterns)
  • Restraint Theory (The cycle of dieting and overeating)
  • Disinhibition (Losing control over eating due to a trigger)

Great job! You've just covered the core components of Eating Behaviour. Take a break, have a snack (listen to your VMH!), and come back to review the neural mechanisms one more time later—they are usually the trickiest part!