Overweight & Obesity

Nota:

• Metabolic fuel intake is greater than the energy required. Storage of excess (Largely as triacylglycerols in adipose tissue)

1. BMI = Weight(kg)/Height2(m)

   Nota:

   • Not an accurate measurement for those who have a high muscle mass. BMI is designed to give an idea of excess adipose tissue
2. Fat Measurements (Adiposity)
3. Body fat Density

   Nota:

   • 0.9g/ml
4. Body Water %

   Nota:

   • Dose of water given. Labelled with 2H or 18O. Measure dilution of label excreted in urine or saliva
5. Potassium

   Nota:

   • Only found in fat free mass. Measurement of the y-radiation from naturally occurring Potassium isotope

Nota:

• "The long term sum of all the forces of metabolic equilibrium for a given nutrient" Nutrient Intake - Nutrient Utilization = Change in body stores. 0 Balance = Match. Stores remain constant. + Balance = Intake exceeds utilization, stores expand - Balance = Utilization exceeds intake, stores become depleted

1. RMR + Physical Activity
2. Basal Metabolic Rate
3. Thermic effect of food/Diet-Induced thermogenesis
4. Non-Shivering thermogenesis
5. Unconcious Activity
6. Purposeful Activty

Nota:

• Equation is extremely simple. Highly complex regulating pathways and mechanisms involved in regulation of food intake and energy expenditure and body weight management

1. Fuel Sensing Mechanisms
2. Signals
3. CNS/Hypothalamus
4. Effector Signals
   1. Decrease Appetite/Increase Energy Expenditure

      Nota:

      • Epinephrine - Beta adrenergic Estrogens
   2. Increase Appetite/Decrease Energy Expenditure

      Nota:

      • Epinephrine - Alpha adrenergic Androgens Glucocortoids Insulin Progesterone

1. Neuro/Gut Peptides
   1. Orexigenic
      1. Ghrelin

         Nota:

         • Synthesized in the stomach. Levels disrupted in Kidney disease and Cancer. Ghrelin antagonists may be useful in combating obesity
   2. Anorexigenic
      1. GLP-1

         Nota:

         • Released from L cells in GI tract in response to food intake. Anoretic and Incretin type peptide. Increases insulin release, positive glucose control and causes weight loss. Antagonists include Exanotide and Liraglutide
      2. OXM

         Nota:

         • Product of Pro-Glucagon cleavage.  Co-secreted with GLP-1 and PYY after food intake. Trialed in obese patients for weight loss
      3. Amylin

         Nota:

         • Peptide, co-secreted with Insulin. Studies show control of blood glucose levels and increase weight loss
      4. PYY

         Nota:

         • Anoretic satiety peptide. Reduced levels found in obese patients. Dose replacement of replacement PYY increases weight loss
      5. PP

         Nota:

         • Secreted in a biphasic manner from pancreatic iselets. POSSIBLE ANORETIC AFFECTS
2. Peripheral tissue signals
3. Afferent neural and Hormones stimuli---Hypothalamus
   1. Arcuate (ARC) and Paraventricular Nuclei
4. Hypothalamic Neuropeptides
   1. Arcuate Nucleus (ARC)

      Nota:

      • Play a central role in regulating and integrating OREXIGENIC AND ANOREXIGENIC signals.
      1. Pro-Opiomelanocortin (POMC) Neurones

         Nota:

         • Appetite inhibiting, producing mealoncortins
      2. Neuropeptide Y (NPY) & Agouti-Related Peptide (AgRP)

         Nota:

         • Co-expressing neurones, appetite stimulating