Lecture 10C-ENERGY BALANCE
8 November 2010
1) Introduction to nrg balance
2) Energy in
3) Energy out
4) Body weight, body composition and health
5) Health risks associated with body weight and body fat
6) SUPPLEMENTS
Introduction to Energy (nrg) balance
Constant spend and refuel- excess stored
Not all excess nrg in is stored-some extra nrg used for maintaining extra body weight
Slow weight loss desirable –otherwise yo-yo effect - diet and exercise is the key
2) Energy in
a)Food composition
Use of oxygen to break bonds- O2 as a nutrient concept
Food composition
b) Food intake
Hunger
Depends on food content of stomach in part—reduced amounts of food—smaller stomach—less demand; larger amounts of food --larger stomach—larger demand
Receptors in gi tract whether nutrient intake has been high or low
Satiation
Stomach stretch receptors, nutrients in the small intestine trigger hormones which affect nerve function –people stop eating
Satiety
Do not start eating again-
Overiding hunger and satiety signals
Boredom, stress, time of day, availability,
sight, taste of food
3) Energy out
Components of energy expenditure
50 % dietary Kcal to ATP and rest radiates as heat
ATP 50 % to work and 50 % to heat there only 25 % of kcal used
Basal metabolism
Just to keep the doors open and the heat and lights on- ie maintaining body temp, breathing, bone marrow operating, heart beating- all basic processes of life
CALCULATED AS: wt x 10 cal/lb
Physical activity
mass and activity (duration frequency and intensity).
Thermic effect of food-
dat, metabolise and store nutrients-energy requirement
Adaptive thermogenesis
Adaptation to stress (eg cold or exercise)- body needs extra energy to build the tissues
GRAND TOTAL REQUIRED
2200 kcal/day for females
2900 kcal/day for men
4) Body weight, body composition and health
Body weight and its standards
a) Weight within range recommended for height and sex
10 % below std-underweight
10-20 % over -overweight
> 20% obese
B) BMI
Kg/m2
underweight- <18.5
correct 18.5-24.9
overweight > 25- 29.9
obese > 30
C) Body fat and its distribution
PERCENT BODY FAT- FOR GOOD HEALTH
MALES FEMALES < 40 YEARS 22 32 > 40 YEARS 25 35
FAT DISTRIBUTION IS IMPORTANT TOO
FOR BOTH MEN AND WOMEN PEAR SHAPE GIVES LOWER RISK OF ATHEROSCLEROSIS
FOR BOTH MEN AND WOMEN APPLE SHAPE GIVES HIGHER RISK OF ATHEROSCLEROSIS
Waist/hip > 0.9 IN MEN AND 0.8 IN WOMEN- APPLE SHAPE-PROBLEMS WITH LDL AND ATHEROSCLEROSIS
5) Health risks associated with body weight and body fat
Health risks of underweight
Preserve lean tissue against wasting
Infertility
Give birth to unhealthy infants
Health risks of overweight
atherosclerosis(stroke) - due to elevated cholesterol and blood pressure
Diabetes-type II diabetes already discussed-insulin resistance and accompanying lipoprotein abnormalites
Cancer- weight and weight gain tied in here- not fully understood why- may be related to hormones
SUPPLEMENTS
MA HUANG-HERB CONTAINING EPHEDRINE- ALLEGED TO INDUCE WEIGHT LOSS
CHROMIUM PICOLINATE- ALLEGED TO BURN FAT
SPIRULINA- POWDER FROM ALGAE- ALLEGED TO SUPPRESS APPETITE
GUAR GUM ALLEGED TO SUPPRESS APPETITE VIA ABSORBING WATER AND BLOATING STOMACH
GYMNENA SYLVESTRE PLANT- CLAIMED TO BLOCK SUGAR ABSORPTION-
ALL BOGUS