STRESS & EATING.pdf

Thursday, February 15, 2024 STRESS & EATING Why Do We Eat? HUNGER (EATING TO LIVE) - Inborn physiological need to eat - When lacking energy: empty stomachs and intestines send signals to the brain, that stimulate - feelings of hunger Prompt us to eat to replenish the body with the energy it needs Ho...

Thursday, February 15, 2024 STRESS & EATING Why Do We Eat? HUNGER (EATING TO LIVE) - Inborn physiological need to eat - When lacking energy: empty stomachs and intestines send signals to the brain, that stimulate - feelings of hunger Prompt us to eat to replenish the body with the energy it needs How animals eat APPETITE (LIVING TO EAT) - Learned response and desire to eat food which is usually associated with the sensory (sight, smell, taste) aspects of food - driven by external forces and influenced by our emotions, social situations, as well as cultural norms How humans eat Appetite: a combination of internal and external factors in uence appetite and consequently the amount and types of food consumed by humans Internal factors: physiologic mechanisms that regulate appetite, with hormones such as neuropeptide Y stimulating food intake and leptin reducing food intake external factors: environmental factors, social factors, and the palatability of foods SATIETY - The feeling of fullness after we have eaten - influenced more by body signals than external factors Internal Factors SET POINT THEORY - Nuclei controlled body weight through a set-point mechanism fl Study — lesion of Hypothalamus in rats Lateral Hyp lesions = never feel hungry = reduced the set point for body weight ✓ Lesioned rats maintain body weight at a new lower level ✓ For example, Ozempic injections reduces need for food = weight loss VMH lesions = always feel hungry = increased the set point for body weight Thursday, February 15, 2024 ✓ No signal to signal satiety = continuous eating ✓ Lesioned rats maintain body weight at a new higher level HYPOTHALAMUS - Ventromedial H: Decreases eating - Lateral H: increases eating Where stress response, eating habits, sexual behaviours are initiated - source of all physiological mechanisms Dual Center Hypothesis If less fat = more carbs (vice versa) - carbs increase glucose (body uses it for fuel) - When glucose reaches max level = vmH - As energy is consumed, glucose levels decrease = lH External Factors POSITIVE INCENTIVE THEORY Suggests that eating is triggered by external stimuli such as the time of day, or the sight and smell of food even if hunger is not felt - eating because it’s time, because it smells good or looks good Factors: - Environmental influences e.g. Food availability, climate, etc. - Emotional factors e.g. Stress, mood, perceptions - Most people under stress eat more - Social influences e.g. Culture, religion, peer pressure - Weddings, holidays, funerals, etc. - Health status e.g. Chronic disease, mental illness - Medication e.g. Appetite suppressing drugs\sensory aspects e.g. Taste, texture and smell of food Thursday, February 15, 2024 Stress Source of appetite and stress: HYPOTHALAMUS HOW DOES STRESS AFFECT APPETITE? Response to acute or chronic stress can lead to physiological changes that include: - slowed gastric emptying - elevation of blood pressure - increase in heart rate - mobilization of energy stores - and decrease in blood flow to non-essential organs, e.g. the digestive system, kidneys, and skin ACUTE VS. CHRONIC STRESS - In order to survive a famine – or chronic stress the body goes into fat storage mode. - During acute stress, the body’s appetite shuts - down – and stored energy is mobilized for fighting or fleeing. Exercise is like triggering your fight or flight response. It revs up your metabolism and dulls your appetite working out suppresses appetite STRESS AND EATING DISORDERS Stress can: - Trigger obesity and bulimic episodes Alter functioning of the HPA stress axis may contribute to the development and maintenance of AN (Roberts et al., 2007) During stressful periods: Individual increase caloric intake, saturated fact and carbohydrate (Roberts et al., 2007) ✓ Body wants to eat more, especially foods that are calorie dense - High levels of dietary restraint seem to play a causal role on the subsequent reduction in dietary restraint Denying all liked foods causes stress = overeating STRESS Increase in negative mood during stress is + related to caloric intake (Epel et al., 2001) - DA release during eating= increased mesolimbic DA neuronal activity ---Pleasure! DA release linked to caloric intake - Eating comfort foods reduces negative hormonal and behavioural changes Thursday, February 15, 2024 Vedhara et al: mastery over our lives = more control over life = negatively correlated with daily cortisol secretion STRESS AND HEALTH BEHAVIOURS - Stress makes people get involved in unhealthy behaviours: ✓ More likely to eat higher fat diets with less fruits and vegetable, engage in less exercise, smoke cigarettes, and consume more alcohol (Baer et al., 1987; Cartwright et al., 2003) EFFECTS OF STRESS ON FOOD CHOICE Oliver et al. demonstrated that snacking behaviour was increased by stress in the majority of respondents regardless of gender or dieting status - Food preference varies with stress levels. Intake of meal-type foods (fruits, vegetables, meat and fish) was decreased during stressful - periods Texture of food plays a role on how well the food alleviates stress - Mildly arousing stressors: increased eating not necessarily negative mood, celebrations - Extreme/Traumatic Stressors: reduce food intake Body on the verge of collapse Study — Stress-induced cortisol and eating behaviour in women Objective: distinguish stress over-eaters from under-eaters Results: ✓ High cortisol reactors (more release) under stress = eat more UNHEALTHY EATING CUES 1. Social Cues Often eating is the primary activity in social settings Wanting to fit into social settings Peer pressure 2. Situational Cues Seeking comfort during crisis/loneliness Avoiding negative feelings Reward 3. Negative Thoughts & Negative Feelings The Cycle of Automatic Eating: ‣ Unpleasant situation ‣ Automatic negative thoughts Thursday, February 15, 2024 ‣ Negative feelings ‣ Eat our emotions