ENERGY BALANCE

16 MARCH 2015

Introduction to energy (nrg) balance As far as energy in the body goes it is a case of constant spend (catabolism or breakdown of energy yielding nutrients) and refill (anabolism or build up of energy yielding nutrients Not all excess energy in is stored-some extra energy is used for maintaining extra body weight Slow weight loss desirable –otherwise get the yo-yo effect - diet and exercise is the key to proper weightmanagement

Energy in governed by a) and b)a) Food composition-calories in food

 b) Amount of food intake driven by:

Hunger 

Satiation 

Satiety 

Overriding hunger and satiety signals  

Energy inFood composition

Food composition – the more carbohydrate, lipid and/or protein in food consumed the greater the amount of energy consumed

O2 helps to make energy from food and, in

that sense, oxygen is a nutrient even though the oxygen in food does not contribute to metabolism of the carbohydrate, lipid and protein in food

  

Energy in Food intake governed in part by hunger-in part hunger depends on food content of stomach:

-smaller stomach requires less food to fill it

-larger stomach requires more food to fill it

-stomach fullness of course stops hunger  -hunger also depends on receptors in the gastrointestinal tract that determine whether nutrient intake has been high or low and this also signals whether one is still hungry

ENERGY INTAKE CONTINUEDFOOD INTAKE ALSO CONTROLLED BY:

Satiation and Satiety  Satiation signal says-when to stop eating Satiety signal says-do not start eating again 

Overriding hunger and satiety signals due to: boredom, stress, time of day, availability of food

sight, and/or taste of food all of which may cause us to continue to eat 

Energy outComponents of energy expenditure 

Basal metabolism 

Physical activity

 

Thermic effect of food 

Adaptive thermogenesis

  

Energy out continued

50 % dietary Kcal goes to make ATP and therest of dietary Kcal radiates as heat

50 % of ATP goes to work and 50 % of ATP goes to heat

therefore only 25 % of dietary kcal used for work 

Basal metabolismJust to keep the doors open and the heat and lights on   -calculated as weight (lbs) x 10 cal/lb 

ENERGY OUT CONTINUEDPhysical activity amount of energy expended depends on in direct proportion to body mass and activity (duration, frequency and intensity). Thermic effect of food-energy utilised to digest absorb and transport and store nutrients 

 Adaptive thermogenesis-energy consumed during shivering Adaptation to stress (e.g. exercise) - body needs extra energy to build tissues

GRAND TOTAL ENERGY OUT 2200 kcal/day for females

2900 kcal/day for males

Measures of body fat distribution

BMI

BMI =kg/m2

  underweight <18.5 correct 18.5-24.9 overweight > 25 - 29.9 obese > 30

BMI is not a good measure of body fat distribution

Measures of body fat distributionWaist circumference Europid Males > 94 cm - increased risk of heart disease, type 2 diabetes, stroke, cancer (including but not limited to colon, prostate, breast)

Europid Females > 80 cm-risk - increased risk of heart disease, type 2 diabetes, stroke, cancer (including but not limited to colon, prostate, breast)

Waist circumference is a good measure of body fatdistribution-particularly good measure of the extent of visceral fat

Health risks associated with body weight and body fatHealth risks of underweight•Tougher to preserve lean tissue against wasting•Infertility•Giving birth to unhealthy infants

Health risks of overweight•Atherosclerosis(stroke) •Diabetes-type 2 diabetes already discussed •Cancer- weight and weight gain tied in here-

not fully understood why- may be related to hormones

Supplements alleged to control bodyweight -all claims are false!!

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 by absorbing water and bloating stomach

Gymnena Sylvestre plant-claimed to block sugar absorption

Energy control (diet) and exercise combined are the best way to control body weight and hence health.

Energy control (diet) and exercise combined prevent excess body fat related diseases