Metabolism and Weight PPT.pdf

7/24/2019 Metabolism and Weight PPT.pdf

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Human Metabolism and

Weight Management


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Outline! Metabolism basics

! Body weight

!

Obesity! Weight management


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metabolism of nutrients


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Endproducts of

Energy Metabolism


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Eliminationof Metabolic

Wastes:Body OrganSystem


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Water! essential nutrient

! Blood is 90% water

! Transportation

!

Body temperature! Tears, synovial fluid, saliva, spinal fluid

! Blood pressure


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Need for Water in the Body

Compared to Intake


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HydrationStatus


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energy balance


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energy expenditure


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body weight


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BMI! Ratio of weight: height

! kg/m2

! lb x 703 /in2

!

interpretation:!


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BMIlimitations?

!BMI has not been validated in acutely ill patients.

!BMI may underestimate body fat in the elderly and others who have lostmuscle mass.

!BMI may overestimate body fat in individuals who have a muscular build.


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Body Composition


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2007 Thomson - Wadsworth


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Methods for Assessing Body

Composition! Bioelectric impedance analysis

! Skinfold thickness

! Underwater weighing! Radiologic methods


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Bioelectrical This method for better accuracy uses four electrodes placed at the wrists and ankles to monitor

the ease of passage of a mild electrical current. (Two electrodes for foot-to-foot passage are notas accurate but are more available to consumers.)

Fat is a poor conductor of electricity; the conductivity occurs through the nonfat parts of the body.

BIA actually estimates the amount of lean body mass, and then the amount of fat is calculatedfrom the difference between the lean body mass and the total weight.

BIA is safe, inexpensive, easily performed, and reasonably accurate, but it is not consideredsensitive enough to detect day-to-day changes experienced by someone trying to gain or lose fat.

Hydration levels, though, may affect accuracy of the BIA readings. Other methods of assessingfat level are triceps skinfold and midupper arm circumference, but likewise these are unable todetect day-to-day changes.


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obesity

prevalence


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2000

Obesity Trends* Among U.S. AdultsBRFSS, 1990, 2000, 2010(*BMI !30, or about 30 lbs. overweight for 54 person)

2010

1990

No Data


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obesity

how?


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obesity

what now?


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obesity

! Prevention

! Diets? Do they work?

! Lifestyle changes

! loss of 5-10% total weight


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Macronutrients and Weight


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protein.

! Highest TEF of all macronutrients

! Slower gastric emptying

! Stabilizes blood sugar

! Preserves lean body mass


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carbohydrate.

! Needed for energy, especially brain

and muscle

! Contains fiber, helps keep full

! Stimulates insulin release

! Insulin --> satiety

! Insulin ---> lipogenic


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fat.! Feelings of satiety and satisfaction

! Lowfat = more hunger

! Stimulates CCK release


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macronutrient ratios.

! Food Pyramid! 10-20% Pro! 50-60% CHO! 30% Fat

! Mediterranean Diet:! Like FP but up to 35%

fat

! Vegan

! 20% Pro! 70% CHO! 10% Fat

! Zone:! 30% Pro! 40% CHO! 30% Fat

! Atkins:! 30% Pro! 5% CHO! 65% Fat


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interpretation.! Can lose weight on any type of calorie restricted

diet

! An emphasis on fat, protein and fiber increasessatiation for easier weight loss

! And potentially a benefit from higher thermic effect

of food and hormonal regulation

! Important to emphasize micronutrient dense foods

during periods of caloric restriction


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Metabolism and Weight PPT.pdf