Nut10 Chapter 3 : Calories PDF

Preview

Summary

NUT10V Video Lecture Notes
Professor Christina Applegate...

Description

Calories: The Energy Basis of Nutrition Energy ● Ability to do work ○ Metabolic ○ Physical How to Measure Energy Value of Foods ● Food ○ Carbohydrate ○ Protein ○ Fat ■ These all have carbon (C) ■ Contain potential energy ● Energy = metabolic work ● Energy = ability to do work ● Energy = physical work Early Scientist (Lavoisier) Made a Comparison Between: ● Fire and Living Animal ● Can figure out energy value of food by burning those pieces of food Heat Measured in Calories ● Calorie ● (Kilocalorie) ● Kcal ○ → all terms equivalent ● 1 calorie = Heat needed to raise 1 liter of H20 1º C Measure Heat ● Potential energy in chemical bonds released Food and Oxygen - Oxidized ● Break chemical bonds ● Release energy ● Release CO2

Bomb Calorimeter - Oxidized ● Break chemical bonds ● Release energy ● Release CO2 ● → Determines calorie value → potential energy Total Potential Energy Released from Food (kcal/g) (bomb calorimeter) ● Carbohydrate → 4.2 Kcal/g ● Fat → 9.4 Kcal/g ● Protein → 5.7 Kcal/g How much energy do you get when you eat carbohydrates? ● Potential energy → body gets ● Carbohydrate 4.2 Kcal/g → 4Kcal/g → value called physiological fuel value → 5% indigestible loss in stool How much energy do you get when you eat fat? ● Potential energy → body gets ● Fat ● 9.4 Kcal/g → 9 Kcal/g → Value called physiological fuel value → 5% indigestible loss in stool How much energy do you get when you eat protein? ● Potential energy → body gets ● Protein ● 5.7 Kcal/g → 4 Kcal/g ■ 10% indigestible loss in stool ■ Energy loss in urine N → urea Physiological Fuel Values = This is the amount of energy your body gets when you eat 1 gram of: ● Carbohydrates → 4 Kcal/g ● Protein → 4 Kcal/g ● Fath → 9 Kcal/g Calories Listed on Label = Physiological Fuel Values

Hot dogs ● How many calories are in a hot dog? ○ Carbo 1g x 4 Kcal/g = 4 Kcal ○ Fat 16g x 9 Kcal/g = 144 Kcal ○ Protein 7g x 4 Kcal/g = 28 Kcal ○ Total = 176 Kcal What Percent of Calories are from Fat? ● (144 fat calories / 176 total calories) x 100 = 82% Note: ● Calories in a meal are additive ● Water + cholesterol + vitamins and minerals = no calories ● Fiber has 0 calories per gram Calories listed on label Diet Project Calculations Your daily intake of: ● Carbohydrate g → total calories and % of calories from carbs ● Protein g → total calories and % of calories from protein ● Fat g → total calories and % of calories from fat Energy Needs - components of your energy requirement 1. Basal metabolic rate (BMR) a. heat/energy needed to keep basic body functions going, such as heart and lung function b. Heart beating, lungs breathing in and out c. Liver doing its maintenance duties i. Measure: - At rest - Fasted 12 hours - 24 hours without exercise - Neutral room temperature 2. Activity - energy needed to perform any activity above the BMR; any body movements above rest (ex: sitting, standing, walking, etc); usually equal to or less than your BMR 3. Thermic effect of food (TEF) - heat/energy needed to digest and assimilate food; smallest component of our energy need, since its value usually falls between 50-200 kcal.

4. Growth - the amt of energy needed to support the cost of building new tissue and the material that makes up tissue (ex: muscle and bone) → taken into consideration for children only when determining a child’s energy requirement Calorie Balance ● Calorie intake ---- calorie output Gain or Lose Body Fat ● 1 lb fat ○ 3,500 calories = 1 lb. fat ○ 3,500 calories excess = gain 1 lb ○ 3,500 calories deficit = lose 1 lb ● Excess calories are converted to and stored as fat in the body ● Weight gain happens when the number of calories coming is is greater than the # of calories being expended through activity. Over time, this increase in fat stores can lead to obesity Calculating BMR ● Body weight taken into account ○ Men: 1 kcal/ (kg x hr) x weight kg x 24 hrs/day ○ Women: 0.9 kcal/ (kg x hr) x weight kg x 24 hrs/day ● Males have a greater BMR per unit of body weight bc males typically have more lean muscle tissue, while females typically have more body fat ● Lean muscle tissue requires more energy to maintain than body fat does. ● The equation used for males is 1.0 kcal/kg body weight per hour, while the equation is 0.9 kcal/kg body weight per hour for females ○ Ex: female - 55 kg ■ 0.9 kcal/ (kg x hr) x 55 kg x 24 hr/day = 1188 kcal/day Factors That Change BMR 1. Age a. With increase in age, BMR decreases; after age 20 BMR decreases 2-3% every 10 years 2. Fasting a. Decreases BMR approx 10-20% 3. Exercise a. Increases BMR (variable effect)

Do Supplements Help Boost Your Metabolism? ● Green tea? Energy Requirement Component: Activity ● Compute based on activity profile expressed as % of BMR ● Category → = % of BMR ● Sedentary → +30% ● Light → +50% ● Moderate → +70% ● Strenuous → +100% ○ Ex: 55 kg woman, moderate activity ○ 55 kg x 0.9 kcal/ (kg x hr) x 24 hr/day = 1188 kcal/day (BMR) ○ Activity = 70% BMR ■ .7 x 1188 kcal = 831 kcal needed for activity Energy Requirement Component: Thermic Effect of Food (TEF) ● Energy needed for: ○ Digestion of food ○ Assimilation of food ○ 5-10% of total caloric intake ○ TEP approx 50 → 200 kcal Calculate TEF ● 5% of the sum (BMR + activity) = TEF ○ Ex: BMR = 1000 kcal/day Activity = 500 kcal/day ● TEF ○ = 5% (1000 + 50/0 ○ = .05 (1500) ○ = 75 kcal Predicted range for BMR → between 1,000 to 2,000 kcal/d What is her energy requirement? ● Female 52 kg → 1.0 kcal/ (kg x hr) ● Strenuous activity → 0.9 kcal/ (kg x hr) 1. BMR = 52 kg x 0.9 kcal/ (kg x hr) x 24 hr/ day = 1123 kcal/day 2. Activity = +100% BMR = 1123 kcal 3. TEF = 5% (BMR + Act.) = 0.05 (1123 + 1123) = 112 kcal

→ Total energy requirement: BMR + Act. + TEF = 2358 kcal/day Diet Project Calculations* 1. BMR = ? kcal 2. Activity = + % BMR = ? kcal 3. TEF 5% (BMR + Activity) = ? kcal ⇒ total energy requirement: BMR + Act. + TEF = ??? kcal/day Example: ● What is his energy intake? ● Male 70 kg → gaining 500 kcal ● Light activity → per day 1. BMR = 1.0 kcal/(kg x hr) x 70 kg x 24 hr/day = 1680 kcal/day 2. Activity = + 50% BMR = .5 (1680) = 840 kcal 3. Gain = 500 kcal 4. TEF = .05 (1680 + 840 + 500) = 151 kcal → TOTAL ENERGY INTAKE = 3171 kcal/day How much fat did he gain in one week? ● 500 kcal/day x 7 days/week = 3500 kcal = 1 lb ● Describe what the “energy value of foods” represents, including how the energy value of foods is measured. ● Calculate the energy value of a food in calories given the macronutrient composition of the food. ● Articulate the components of a person’s energy requirement, including what each component means and how components are determined. ● Calculate a person’s energy requirement and energy intake from given parameters of body weight, sex, activity level, and over/under eating of calories....