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 weight management

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 in Food composition Food composition – the more carbohydrate, lipid and/or protein in food consumed the greater the amount of energy consumed O 2 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 CONTINUED FOOD 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 out Components of energy expenditure Basal metabolism Physical activity Thermic effect of food Adaptive thermogenesis

Energy out continued 50 % dietary Kcal goes to make ATP and the rest 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 metabolism Just to keep the doors open and the heat and lights on -calculated as weight (lbs) x 10 cal/lb

ENERGY OUT CONTINUED Physical 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/m 2 underweight <18.5 correct overweight > obese > 30 BMI is not a good measure of body fat distribution

Measures of body fat distribution Waist 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 fat distribution-particularly good measure of the extent of visceral fat

Health risks associated with body weight and body fat Health 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 body weight -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