Physiology of Eating - L1

1. Mice are not rats and not humans 

2. moslty male animals are used 

1. WHR

2. BMI 

- widely used

- does not take the body composition into account -> great disadvantage

- however, correlations are still seen between BMI & health risks 

1. Energy intake & energy expenditure 

2. Genetics & Environment 

Brown Adipose tissue -> UPC1 (uncouples ATP to produce heath without using muscular activity) 

-> NO convincing evidence yet that BAT as viable pharmacological target for BW loss (activation through pharmacological might even lead to increased heart rate and systolic blood pressure) 

Beta-2 Adrenoceptor = main target for pharmaceuticals to target BAT 

NO! No evolutionary reason why such a mechanism should have been developed -> unnecessary energy waste 

- cold environment & eating increase thyroid hormone secretion (they increase the metabolism in general) 

. Specifially increase heat production through an uncoupling effect: "endogenous uncouplers" 

NO! Polygenic: independent & interacting effects of genetics, epigenetics & the environment 

(monogenic diseases in relation to bodyweight are mostly related to leptin deficiency - but only makes up 5% of obesity cases) 

We are more susceptible to obesity in our current environment than in our past environment. 

Monozygotic twin experiment: received + 1000kcal/d for 100 d -> between groups substantial variances in BW gain, but within groups only slight differences (Environment plays a big role) 

BW changes -> FM establishes faster than FFM -> leads to lower EE -> feedback loop activated to compensate for lean mass which leads to excess caloric intake  -> excess fat deposition 

lead to increased energy intake & weight gain: 

Mechanisms? (Proposals)

1. disconnection of gut-brain communication 

2. Eating rate

3. Protein leverage hypothesis 

endocrine changes -> higher food reward -> lower thermogenesis & PA -> more fatigue -> higher EI & lower EE 

1. health care costs due to comorbidities 

2. comorbidities (heart attack, fatty liver disease, diabetes..)

3. negative stigma + people are blamed for their condition