Editing Obesity background (section)

== Pathophysiology ==

* In general, there is     persistent hunger that is not satiated by the amounts of food that satisfy     the non-obese
** This leads to long-term      positive energy balance, and accumulation of adipose tissue
** Adipose tissue eventually      develops reduced ability to assimilate excess calories
** This leads to fat      redistribution to other tissues, causing diverse health consequences
* Metabolic actions of adipose     tissue
** Increased secretion of      'adipokines' - leptin, adiponectin, resistin and inflammatory cytokines -      comes from white fat, as opposed to brown fat
** Causes chronic low-grade      inflammation, interfering with cellular processes, leading to metabolic      derangements (T2DM, etc)
* Ghrelin - the 'hunger     hormone'
** Levels decrease after meals
** Acts on hypothalamus
** Primarily produced in fundus      of stomach
** Regulates hunger together      with leptin
* Genetic
** Specific genes - FTO, MC4R -      however these only rarely are the sole cause of obesity, and generally      become apparent in childhood.
** Syndromes - Prader-Willi      (deficits in ghrelin signalling)
* Microbiome
** May be a relationship      between gut microbiome and obesity, suggested by some animal studies
* Nutrition
** Hypoalbuminaemia
** Vitamin and micronutrient      deficiencies are common
* Weight regain
** Body defends fat vigorously
** Increased hunger, driven by      ghrelin
** Decreased energy      expenditure, driven by multifactorial neurohormonal changes including      reduced SNS input