The Rest of Chapter 41

ObesityLeptinFood Pyramid

E. Obesity

• Increasing numbers of Americans are obese• Obesity-related conditions

Type 2 diabetesBreast cancerHeart disease Colon cancerHypertension Gout (temporary

athritis due to uric acid)Gallstones Osteoarthritis

Body-Mass Index

• An indicator of obesity-related health index

• BMI = Weight (lbs) X 700----------------------------- Height (inches)2

• BMI greater than or equal to 27 indicates health risk…maybe

Maintaining Weight

• Caloric input must equal caloric use• Calories burned depends upon–Activity level –Age–Height and build

Fighting Fat

• Fat-storing cells are an adaptation for survival in lean times

• Once formed, fat cells are forever = MYTH

• Dieting decreases amount of fat in cells

• Dieting triggers metabolic slowdown

• Exercise enhances metabolic activity

F. Leptin

• Hormone that affects appetite and metabolic rate

• Product of the Ob gene• Faulty Ob gene may contribute to some

human obesity…rare• Also used in treatment of lipodystrophy…

improper storage– Defective fat tissue, fat is deposited in isolated

places…liver…face

Parabiosis: mutant mouse surgically attached to wild type mouseweight loss.

Leptin “cures” obesity in leptin deficient mice and in overfed mice.

Leptin treatment of human diseases:Congenital leptin deficiency (rare)Lipodystrophy (inability to deposit fat in fat tissue)

Leptin action:Hypothalamus (brain)Major area of action-arcuate nucleus Activates pathways that signal satiety and promotes energy expenditure

G. Food Pyramid

http://www.washingtonpost.com/wp-srv/nation/daily/graphics/diet_042005.html

What’s wrong with the pyramid?

Harvard School of Public Health• Pyramid is based on influence of lobbyists as

much as dieticians and research• Has not changed to reflect new research• Cannot account for variation in disease

susceptibility, culture, quality of food

http://www.hsph.harvard.edu/nutritionsource/pyramids.html

Summary

• Anatomy of human digestive system• Tasks of the entire digestive system• Mechanical and chemical digestion in each

region of the GI tract• Rumination• Obesity and the ob/ob mouse• Food Pyramid