Acrostic: ENERGY ENERGY

Energy Chapter 12: The Energy Balancing Act Essential Question: How do I use the different calculations for energy in dietary planning and the selection of nutrient dense foods?

GPS: FNW 1C FNW 1: Students will discuss basic nutrient requirements and their use in dietary planning. C: Define a calorie, compare energy sources, compute Basal Metabolic Rate, Body Mass Index, and Waist-to-Hip Ration; apply outcomes to dietary planning and selection of nutrient dense foods.

Key Questions What is a calorie? How do the different energy sources compare? How do I compute Basal Metabolic Rate, Body Mass Index, and Waist-to-Hip Ratio? How can I apply BMR, BMI, and Waist-to-Hip Ratios to dietary planning?

Key Vocabulary

Part1: What is a calorie? Standard: Define calorie

What is a calorie? Definition – Unit of measure A measure of the energy value of food – and of how much energy will be transferred to the person who eats it. Amount of energy needed to raise the temperature of 1 kilogram of water (about 4 cups) from 15oC to 16oC Calor = heat Calories are NOT a substance present in food and do not qualify as a nutrient

What is a calorie? Caloric value of food: Calories in food are measured by measuring the amount of heat produced when food is burned. Determined in a “bomb calorimeter” by burning it completely in a container surrounded by a certain amount of water A piece of food is precisely weighed, then it is placed in a calorimeter. The chamber holding the food is surrounded by a container holding a kilogram of water. After the food is burned completely, the change in water temperature is accurately measured. Each degree of increase on a Celsius thermometer equals one calorie of energy given off by the food

What is a calorie? Researchers have measured the calories in a wide range of foods listed in food composition tables. Have also determined the energy yield of one gram of a pure nutrient: Carbohydrates and proteins = 4 calories Fats = 9 calories (means that fats produce twice the amount of energy of the other two nutrients)

What is a calorie? Calorie Density: Definition – concentration of energy in a food Fats are a concentrated source of energy which means that foods that are high in fat are calorie dense Foods that are high in water lack calorie density because water yields no energy

Part 2: Energy Sources How do the different energy sources compare?

Energy Sources Energy – ability to do work Cannot be created or destroyed, but can be changed from one form to another When you eat, you take in chemical energy stored in food and it is changed into mechanical energy when you move. Another form of energy is body heat Energy balance is the key to weight management: calories in should equal calories out in order for weight to not change.

Energy Sources Energy Input: Consuming foods Three nutrient groups provide energy: Carbohydrates = 43-58% of daily calories Fats = 30-45% Proteins = 12% Alcohol provides calories, but is considered a drug, not a nutrient

Energy Sources

Part 3: Energy Output How do I compute Basal Metabolic Rate, Body Mass Index, and Waist-to-Hip Ratio?

Energy Output The calories you burn throughout the day You need energy for basal metabolism, physical activity, and thermic effect of food These three account for the calories you expend each day

Energy Output Basal Metabolism Definition – amount of energy required to support the operation of all internal body systems except digestion You are burning energy 24/7 During sleep – internal activity continues Your brain and liver use about 40% of your body’s energy when resting. Basal metabolism keeps your body alive when it is at rest and includes the energy your body uses every day to breathe, circulate blood, and maintain nerve activity Secreting hormones, maintaining body temperature, and making new cells are also part of basal metabolism Compares to energy in the home – you still use energy (electric or gas) when no one is home

Energy Output Basal Metabolic Rate BMR Rate at which the body uses energy for basal metabolism In general, women require 0.4 calorie per pound of body weight per hour and men require 0.5 calorie per pound Formulas: Men: weight in pounds x 0.5 calorie per pound = basal energy needs per hour x 24 hours per day = basal energy needs per day Women: weight in pounds x 0.4 calorie per pound = basal energy needs per hour x 24 hours per day = basal energy needs per day

Energy Output Basal Metabolic Rate Example: woman @ 120 pounds 120 pounds x 0.5 = 60 x 24 hours = 1440 calories Example: man @ 120 pounds 120 pounds x 0.4 = 48 x 24 hours = 1152 calories

Energy Output BMR What affects BMR? Body structure, body composition and gender A tall person will have a higher BMR than a shorter person because the taller person has more body surface area through which heat is lost. Body composition – percentage of different tissues in the body such as fat, muscle, and bone A person with a larger proportion of muscle tissue will have a higher BMR than someone with more fat tissue – it takes more calories to maintain muscle than it does fat. Males generally have a higher BMR than females because men usually have more lean body mass Temperature (both inside and outside the body) Fever increases the BMR Adjusting to hot or cold temps in the environment increases BMR

Energy Output BMR What affects BMR? Thyroid Thyroid gland secretes the hormone thyroxine, which regulates basal metabolism Overactive thyroid produces too much thyroxine and increases BMR This is why thyroid diseases can affect a person’s weight Age BMR tends to decline with age – approximately a five percent decrease in BMR every 10 years past the age of 30 People over the age of 50 must reduce their energy intake up to 200 calories per day to avoid weight gain Older people who remain active do not experience as much decline Diet Diet low in calories decrease BMR about 10-20 percent because the body is responding as if in famine (makes adjustments to preserve life as long as possible) Will cause difficulty reaching weight goals

Energy Output BMR What affects BMR? Periods of growth Higher during periods of growth – infants, children, and teens have a higher BMR than adults Women have a higher BMR during pregnancy Due to this – infants, children, teens and pregnant women should not reduce their calorie intake unless advised by a doctor; these groups need the nutrients provided by a variety of foods Increasing physical activity is a more healthful choice than reducing calories for these groups. Other Notes: Some of these factors are temporary – pregnancy and fever You have very little control over these factors which means that you have very little control over your BMR The ONE way to change your BMR – adding a regular exercise program which will help you develop more muscle tissue Generally the greater the proportion of lean tissue in your body, the higher your BMR

Energy Output Physical Activity This is the second category of energy needs You need energy to move your muscles and for the extra work of breathing harder and pumping more blood Energy output varies depending on body size – the larger the body size, the greater the amount of energy needed to make the muscles work A 180 pound person burns more calories walking than a 120 pound person walking at the same pace The actual amounts of muscle movement also affects energy output – you will burn more energy if your swing your arms while walking

Energy Output Physical Activity Sedentary – activities that require much sitting Watching TV, studying, working in an office, driving, using a computer People who do a lot of sedentary activity need to make a point of including physical activity in their daily lives Burning more calories Try looking for more energy-intensive ways of completing your daily tasks Taking the stairs instead of the elevator; swing arms when walking; stand rather than sit; park further away from destination

Energy Output Physical Activity Determining Caloric Needs for Physical Activity Indirect calorimetry – measurement technique requires a person to wear an apparatus while performing a specific activity. The apparatus measures the person’s oxygen intake and carbon dioxide output. Oxygen consumption is required to burn calories which is why you breathe harder when running or working hard. The researchers then use math formulas to convert the gas exchange into calories used. Formula for personal energy expended: calories used per hour x hours of activity = energy expended Add all of the calculations together for a 24 hour period to determine amount of energy expended per day.

Energy Output Thermic Effect of Food Third energy need Definition – energy required to complete the processes of digestion, absorption, and metabolism – energy needed to extract the energy from food Depends slightly on the types and amounts of foods eaten. Generally equals 5 to 10 percent of your combined basal metabolism and physical activity needs. Remember – the calorie ranges you used to calculate your energy needs for physical activity included basal metabolism Formula – calculated total energy expenditure for the day by .1 = reasonable estimate of energy used for the thermic effect of food For most people, approximately 60-65 % of energy output is for basal metabolism, 25-35% for physical activity, 5-10% for thermic effect of food For athletes, a lower percentage of energy output is for basal metabolism and a higher percentage for physical activity Calculating total energy needs is difficult for most people, but you can use your estimates to help you determine whether you are balancing your energy input and output.

Energy Imbalance The two sides of the energy equation are not always in balance. Energy imbalance occurs when a person consumes too few and too many calories for his or her energy needs. A regularly occurring energy imbalance will cause a change in body weight.

Energy Imbalance Energy deficiency – energy intake is less that energy output Several factors can result in energy deficiency: poverty, famine, illness, or eating a low-calorie diet The body’s response: The body first uses energy from carbohydrates, fats, and proteins in food to meet its energy needs; if there is not enough available, the body draws on its stores of energy (liver glycogen – the stored form of glucose from carbohydrates for use by non-muscle tissue.) After about 4-6 hours, stores are depleted, the body will draw on fatty tissues. Weight loss will occur. The nervous system cannot use fat as a fuel source – requires glucose which cannot be obtained by fat The body can use amino acids from proteins in lean body tissues to make glucose to feed the nervous system – it has to break down muscle and organ tissues. Muscle tissue is 75% water; therefore breaking down muscle proteins causes a rapid weight loss due to loss of body fluids and can also cause muscle weakness and can lead to a number of dangerous health consequences.

Energy Imbalance Energy deficiency – The body’s response cont. When carbs are not available, the body will take steps to limit muscle deterioration. It will slowly begin to use another method to feed the nervous system – by changing fatty acids into compounds called ketone bodies The nervous system can use ketone bodies to meet some of its energy needs Reach the nervous system through the blood stream An abnormal buildup of ketone bodies is called ketosis which can be harmful because it changes the acid base balance of blood Carbs are always important because they are the preferred fuel for nerve and brain cells to function High protein or low carb diets are not recommended because they cause muscle tissue to be broken down and large amounts of ketones to form. Carb intake should also be sufficient to preserve muscle tissue which will cause the body to use fat stores, not muscle, for energy and weight loss will occur from the loss of fat, not protein

Energy Imbalance Energy Excess – occurs when energy intake is greater than energy output Excess calories can be stored in adipose tissue and the body can use this stored energy when there is not enough food intake to meet immediate energy needs. If energy excess occurs on a regular basis, weight gain will result. An excess of 3500 calories in the diet leads to 1 pound of stored body fat. Most overweight people have gained weight slowly over a period of years – consuming an extra 25 calories each day adds approximately 2 ½ pounds each year. Excess adipose tissue is a health concern – the greater the amount of fat carried on the body, the greater the risks for related health problems

Determining Healthy Weight This may not match the media image of a perfect body – it is the weight at which your body fat is in an appropriate proportion to your lean tissue which reduces your risks of a number of serious medical problems. Several ways to determine if your weight is healthy: Height weight charts Body Mass Index Measuring Body Fat Waist-to-Hip Ratios

Determining a Healthy Weight Body Mass Index BMI A calculation of body weight and height used to evaluate weight. To calculate: divide your weight in pounds by the square of your height in inches (145 pounds / 692 inches) x 705 = BMI (145 / 4761) x 705 = BMI 0.0.05 x 705 = 21.5 (rounded) BMI There is a chart in your book on page 220 showing estimated BMI Healthy weight = a BMI of 18.5-24.9 Overweight = a BMI of 25-29.9 Obese = anything over a BMI of 30 Underweight = BMI less than 18.5 Not an appropriate tool for everyone – body builders have excess muscle weight Less clear-cut for children and adolescents, whose bodies are still growing and vary according to age and sex (see chart on page 221)

Determining a Healthy Weight Waist-to-Hip Ratios Considering the location of excess fat in the body Some fat deposits are more directly related to health risks than others Apple-shaped -- People who carry more fat around their middles (most common in women) Pear-shaped – carry weight around their hips and thighs Apple shapes pose a greater risk than pear shaped Formula – measure your waist at its narrowest point, then measure your hips at their fullest point. Divide the measurement of the waist by the measurement of the hips. Woman with a 28 inch waist and a 38 inch hips: 28/38 = 0.74 Waist to hip ratios over 1.0 in men and over .85 in women are linked to increased health risks

Determining a Healthy Weight Height-Weight Tables Lists a weight range for each height Weights near the high end of each range apply to people with a greater proportion of muscle and bone tissue – muscle and bone are denser than body fat Weighing less than a height-weight table suggests is not always a bad thing, better to be less than more; but it can indicate a serious health problem Drawbacks They are not precise and not designed for people under the age of 19 Do not take into consideration body composition or individual health risks

Determining a Healthy Weight Body Fat Measuring Methods Analyzing the percentage of fat in your body For men, over 25 percent is excessive – aim for 15-18% For women, over 20% aim for 20-25% Skin-fold test – uses a tool called a caliper to measure the thickness of a fold of skin; an estimate is then made to determine how much of the thickness is due to subcutaneous fat (fat that lies underneath the skin, and accounts for about half of the fat in the body); often taken on the thigh, upper arm, abdomen, and/or back Pinch test – grasp the skin on the back of your upper arm halfway between your shoulder and elbow. Pinch this fold between your thumb and forefinger. Be sure to grasp only the fat, not the muscle. A distance between your thumb and forefinger of more than one inch may indicate a high percentage of body fat. Bioelectrical Impedance – measures the body’s resistance to a low-energy electrical current. Lean tissue conducts electricity, whereas fat does not. The more fat a person has, the more resistance there is to the flow of the electrical current. The measure of resistance is then converted to a percentage of body fat.