Lect11 EnergyBal

Lect11 EnergyBal - 10/7/10 What we eat How we use energy...

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Unformatted text preview: 10/7/10 What we eat How we use energy Posi%ve: you eat more energy than you use  ­ ­ gain weight Nega%ve: you eat less energy than you use  ­ ­ lose weight Hunger/ Sa%ety: 1.  Depends on: a.  Amount of food consumed b.  Availability of certain nutrients 1.  GI tract: •  Gastric stretching •  CirculaBng nutrient content •  Hormones: Ghrelin, CCK 2.  How is this informaBon transmiCed? 2.  Pancreas: Insulin 3.  Adipose Bssue: LepBn 1 10/7/10 Energy to maintain life processes •  Depends on: –  Age, Growth –  Height, % lean Bssue –  FasBng, starvaBon, malnutriBon –  Fever –  Hormones: thyroxin 1.  Indirect calorimetry: Basal Metabolic Rate (BMR) 2.  Direct calorimetry 3.  Stable isotope measurements 4.  Use an equaBon 2 10/7/10 Energy Out: 2. Physical Activity •  •  •  •  Running 10 mph Walking 3.75 mph Walking 2.5 mph Sleeping 897 kcal/hr* 300 200 80 Energy cost for digesBon: approx 10% of kcal eaten Fat: 2 ­3% Carbohydrates: 6 ­8% Protein: 15 ­30% Alcohol: 20% *You would have to run 39 miles at that rate to theoretically lose 3500 kcal = 1 lb fat Energy Out: 4. Adaptive Thermogenesis •  Heat producBon, shivering •  Excess heat from overeaBng •  AdapBon to trauma, stress •  VERY DIFFERENT for different people Excessive amount of adipose Bssue in relaBon to lean body mass 1.  How do we measure it? 2.  What causes it? 3 10/7/10 BMI Anthropometry Bioelectrical Impedance Body Density: water displacement •  Body Density: air displacement •  DXA: dual energy X ­ray •  •  •  •  BMI = Weight (kg)/ [Height (m)] 2 Problems: •  No accounBng for muscularity •  same for men and women •  same for all races •  Waist vs Hips: Not all fat is equal •  No accounBng for populaBon age Comparison with DXA Bod Pod r=.93 Calipers r=.87 BMI r=.81 Impedance r=.68 Basal metabolism Thermic effect of food Thermogenesis Calorimetry Ghrelin LepBn Adipose Bssue BMI Anthropometry Bioelectrical Impedance Body Density DXA 4 ...
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This document was uploaded on 02/05/2011.

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