Brown Fat Information

Here are three more of those of weight loss myths: green tea, water and all the various other herbs and spices that supposedly increase metabolism; late night eating leading to gaining weight; and finally my personal favorite: the starvation mode.

As with the last video concerning these myths, here is the scientific research behind what I say:

- Foods That Increase Metabolism

Dulloo AG, Duret C, Rohrer D, Girardier L, Mensi N, Fathi M, et al. Efficacy of a green tea extract rich in catechin polyphenols and caffeine in increasing 24-h energy expenditure and fat oxidation in humans. Am J Clin Nutr 1999;70:1040-5.

Diepvens K, Kovacs EM, Nijs IM, Vogels N, Westerterp-Plantenga MS. Effect of green tea on resting energy expenditure and substrate oxidation during weight loss in overweight females. Br J Nutr. 2005 Dec;94(6):1026-34.

Boschmann M, Steiniger J, Hille U et al. Water-Induced Thermogenesis. Journal of Clinical Endocrinology & Metabolism Vol. 88, No. 12 6015-6019

Brown C, Dulloo A, Montani JP. Water-Induced Thermogenesis Reconsidered: The Effects of Osmolality and Water Temperature on Energy Expenditure after Drinking. Journal of Clinical Endocrinology & Metabolism Vol. 91, No. 9 3598-3602

http://www.ncbi.nlm.nih.gov/pubmed/10584049
http://www.ncbi.nlm.nih.gov/pubmed/16351782
http://jcem.endojournals.org/cgi/content/abstract/88/12/6015
http://jcem.endojournals.org/cgi/content/abstract/91/9/3598

- Late Night Eating

Sullivan EL, Daniels AJ, Koegler FH, Cameron JL. Evidence in female rhesus monkeys (Macaca mulatta) that nighttime caloric intake is not associated with weight gain. Obes Res. 2005 Dec;13(12):2072-80.

http://www.nature.com/oby/journal/v13/n12/full/oby2005257a.html

- Starvation Mode

Keys A, Brozek J, Henschel A, Mickelson O, Taylor H. The biology of human starvation. Minneapolis: University of Minnesota Press, 1950.

Elia M. Effect of starvation and very low calorie diets on protein-energy interrelationships. Protein-Energy Interactions, 1992.

http://www.unu.edu/unupress/food2/UID07E/uid07e11.htm

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Human babies and hibernating or cold-adapted animals are able to maintain body temperature (a process called thermogenesis) due to the presence of brown fat. Brown fat has a high concentration of mitochondria. The mitochondria in them have a protein called thermogenin, which allows the flow of hydrogen ions through the inner mitochondrial membrane (bypassing the ATP synthase). Based on this and your understanding of cellular respiration, propose a mechanism by which brown fat helps keep animals warm.

Mitochondria produce ATP using the energy released from the electrons through the ETC. As the electrons release energy, H ions are pumped across. This creates a stored charge that is released when the H ions pass through ATP synthase. This energy is used to phosphorylate ADP to make ATP.

If instead the H ions are allowed to flow across the membrane, the energy that they have is released as heat and not used to make ATP.

a. hibernation
b. countercurrent heat exchange between vessels that service the extremities
c. raising fur or feathers
d. vasodilation of surface vessels
e. vasoconstriction of surface vessels

–Which of the following sections of the mammalian nephron is incorrectly paired with its function?
a. bowman’s capsule and glomerulus-filtration of blood
b. proximal tubule-secretion of ammonia and H+ into filtrate and transport of glucose and amino acids out of tubule
c. descending limp of loop of Henle-diffusion of urea out of filtrate
d. ascending limp of loop of Henle-diffusion and pumping of NaCl out of filtrate
e. distal tubule-regulation of pH and potassium level

–the rate of metabolic heat production can be increased by
a. nonshivering thermogenesis
b. storage of brown fat
c. shivering and vasoconstriction
d. thick layers of blubber and countercurrent heat exchanges
e. all of the above

D
C
E