Lecture 39 Flashcards
How many new zealanders are obese? What is the current typical option?
About 28% of New Zealanders are obese yet there were less than 600 bariatric surgery spaces available each year. People want to think they can achieve population level weight loss by diet and exercise but just doesn’t seem to happen.
What is body mass index and what are some values for NZ?
body mass index is given by w / h^2 where w is weight in kilograms and h is height in metres. A BMI over 30 is obese, 25 to 30 is overweight, 20 to 25 is healthy and less than 20 is underweight. In New Zealand in 2003 20% of men and 22% of women were obese while 42% of men and 30% of women were overweight.
What are some disease examples related to BMI?
Type II diabetes (increases heavily), coronary heart disease, hypertension and cholelithiasis risk increase with increasing BMI.
How much fat can we mobilise in a day and what parts of metabolism are variable?
We can only mobilise at max roughly 200g of fatty tissue per day due to albumin amounts. People tend to go back to the weight they started at upon diet and exercise though. Our basal metabolic rate is not variable and is required for performance of cellular and organ functions, physical activity and adaptive thermogenesis (responses to termperature and diet via brown adipocyte mitochondria, skeletal muscle and other sites) are variable. Uncoupled mitochondria (no electron transport chain) produce heat, not ATP.
What is brown fat? How does it work?
Brown fat is a special thermogenic tissue found in hibernating animals, humans have it as babies and less in adults. It keeps hibernating animals and babies warm and contains many mitochondria and fat droplets. Its ability to produce heat is done via uncoupling protein, this is present in the inner mitochondrial membrane, they are regulated proton channels in the membrane which allow protons to go through and hence uncouple ATP sunthesis from fatty acid oxidation and heat is released, increasing the metabolic rate and burning excess fuels. It is found largely in the chest and shoulder areas.
What is diet-induced thermogenesis
Diet-induced thermogenesis involves the idea of activating UCP in brown adipose tissue to burn off excess dietary energy. This could be done to stimulate existing BAT, switch on BAT differentiation and growth and possibly transplant engineered BAT.
Where else have uncoupling proteins been found?
Uncoupling proteins have also been found in white adipose tissue (UCP2, UCP3) and in muscle. These may act to raise metabolic rate and release heat and raise metabolic rate.
What are some possibilities for weight loss via heat production?
Isolating progenitors of BAT tissue, expressing transcription factors to promote them (e.g swapping white to brown) and then transplanting them back to the donor to generate functional BAT. Pharmaceutically injections could bbe done to increase action of BAT cells or switch on the function in White adipose tissue or muscle.
What is a good example of an obesity gene in mice? Why?
There are obese genes which increase the odds of an individual becoming overweight/obese, a good example of this in mice is the leptin gene, leptin is a hormone secreted from “fat” fat cells which signals decrease of food intake, increases energy expenditure and maintains normal animal via energy balance. A problem with the leptin receptor within the hypothalamus and several other tissues will have the same effect. Leptin is also found in humans for the same conditions.
What are some factors of obesity development and what is xenical?
Factors which influence development of obesity include: monogenic syndrromes, suceptibility genes, exercise, food intake and culture. Xenical is a drug which reduces fat absorption by reducing pancreatic lipase.
