Obesity Flashcards
What is BMI?
BMI = w/h^2
> 30 = obese
25 - 30 = overweight
20 - 25 = healthy weight
< 20 = underweight
As BMI increases what risk increases?
Risk of type 2 diabetes, hypertension and gall stones (cholelithiasis) and CHD (coronary heart disease) increases with increasing BMI
What is energy storage?
Capacity to store energy in adipose tissue, if we build up large amounts of TAG it is also stored in muscle and liver which may contribute to insulin resistance
How can you lose weight?
If you restrict your calorie intake the max. energy you can burn is ~200g/day which results in losing weight however after diets and exercise 90% of people return to their original weight
What contributes to energy expenditure?
BMR - 50% of energy expenditure required for performance of cellular and organ functions
10% is adaptive thermogenesis, responds to temperature and diet, stimulated by SNS, occurs in brown adipocyte mitochondria, skeletal muscle and other sites
40% is physical activity- have control over it hence variable
How can DNP be used to lose weight?
DNP can uncoupled mitochondria, deprotonate and dissipate proton gradient hence can help with weight loss however, leads to neurological disorders and death
What is brown fat?
Brown fat is special thermogenic tissue that is able to uncouple mitochondria (many mitochondria and fat droplets), babies have it around vital organs to protect and generate heat. Keeps hibernating animals warm and babies warm
What is uncoupling protein?
UCP makes channels in inner mitochondria membrane, proton channels in membrane that completely uncouple ATP synthesis in fatty acid oxidation, proton gradient dissipates releasing heat therefore increased metabolic rate and burning of excess fuels
How do penguins metabolically adapt to cold environments?
Penguins use avUCP to generate heat and stay warm, highly expressed in mitochondria of pectoral muscles, oxidises fatty acids to generate heat
What is beige adipose tissue?
Related uncoupled proteins (UCP2 and UCP3) have been discovered in white adipose tissue and muscles.
This tissue is called beige adipose tissue and is formed following exposure to cold. May act to raise metabolic rate and release heat to burn off excess energy and prevent obesity. Recent research implicates UCP burning off fat after bariatric surgery
What are some possible ways to combat obesity?
Stimulate existing brown adipose tissue
Switch on brown fat differentiation and growth
Transplantation of engineered BAT
Does obesity have a genetic component?
Obesity has a genetic component that can run in families, there are as many genes that control height that control weight, on top of this there are environmental and life style factors
What is the gene that affects obesity?
The gene that codes for obesity is leptin, a 16kDa protein. If leptin is not secreted from ‘fat’ fat cells (homozygous mutation) it cannot send signals that would normally decrease food intake and increase energy expenditure to maintain normal animal energy balance hence if no leptin present cannot maintain energy balance
What is the leptin receptor?
The receptor for leptin is present in the hypothalamus of the brain and several other tissues, it is absent in the homozygous mutant leptin resulting in no leptin being secreted from adipose tissue as no leptin receptor present
Most obese humans appear to be resistant to the leptin signal
What is severe early onset obesity?
Severe early onset obesity is constantly demanding food, no serum leptin and homozygous for frameshift mutation in leptin gene. Treated with recombinant human leptin therapy for 1 year, decreased food intake resulting in16kg weight loss in 1 yr due to fat loss
