g leptin endocrine function Produce cytokines and pro inflammatory factors that

G leptin endocrine function produce cytokines and pro

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Produce hormones e.g. leptin (endocrine function) Produce cytokines and pro-inflammatory factors that may contribute to atherosclerosis 75 , Last accessed Aug 2014
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76 Understanding Pathophysiology, Craft et al., 2011, Box 35-1
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Adipose cells Cell size increases in children and adults (hypertrophy) Cell number increases in children (hyperplasia) But the number remains constant after adolescence Gain weight Cell size decreases Cell number remains the same Lose weight 77
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Cause of Obesity Energy intake Excess energy is stored as adipose tissue Energy expenditure 78
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Energy balance Understanding Pathophysiology, Craft et al., 2011, Fig 35-4 79
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Energy expenditure 1 calorie = 4.2 joules Average intake goal: 7300-8900 kJ Athletes / labourers: 15000 kJ / day Intake for energy reduction: less 2000-4000kJ 80
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Regulation of food intake and energy storage Approximately ¼ of energy ingested reaches functional systems of cells Most of this is eventually converted to heat by protein metabolism, muscle activity, and other organ/tissue activity Excess energy is stored as fat 81
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Control of Energy Intake Guyton, Textbook of Medical Physiology, 11 th edn, Fig 71.1 Structure/substance Function Stretch receptors (stomach) Inhibits food intake Gastrointestinal hormones Inhibits food intake Ghrelin (from stomach) Stimulates food intake Leptin (from adipose) Inhibits food intake 82
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WHO Technical report series 894, 2000, Table 7.2 83
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Hormonal factors: Leptin Adipose cells Secrete leptin Promotes satiety, suppresses appetite Excessive number of adipose cells Very high secretion of leptin Ineffective in suppressing appetite Leptin resistance Normal body weight Obesity 84
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Leptin and obesity Understanding Pathophysiology, Craft et al., 2011, Fig 35-6 85
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Genetic factors Many genes influence obesity Genetics studies using adopted twins: One overweight parent 40% chance of becoming overweight Both parents overweight 80% chance of becoming overweight 87
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Genetics vs Lifestyle? Rate of obesity in last 10 years 50% increase Gene pool in last 10 years 0% change Lifestyle factors 88
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Modifiable Risk Factors (1) Eating habits High in energy intake and energy dense, alcohol, sugary drinks High in saturated fats and simple carbohydrates (sugars) Low in fruits, vegetables and complex carbohydrates Low in vitamins, minerals and protein Sedentary lifestyle Physical inactivity in work and recreation 89
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Modifiable Risk Factors (2) Stress Hormonal alterations Emotional eating Lack of sleep Smoking Associated with abdominal fat accumulation Those who quit gain 5-6kg in 1 year, need for education Socioeconomic Low socioeconomic, low education, rural areas 90
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BMI: Body Mass Index Index of weight-for-height measurements Classify healthy, overweight and obesity weights An estimate of body fat BMI = weight (kg) / height (m 2 ) Eg: BMI = 75kg / 1.75m 2 = 24.5 92
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BMI Classifications Understanding Pathophysiology, Craft et al., 2011, Tab 35-1
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