Estimating calorie and nutrient needs

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  • 1. If you pick up any health or fitness magazine, you’ll likely see an array of diet and calorierecommendations, most of which are designed for weight loss. Some say 1200 per day. Anothermay say 1500 per day. So, how much is enough? Calories come from all the different foods andbeverages we consume and provide energy for our bodies. The energy in food is measured inkilocalories (Kcal), also known as Calories (C). However, it is common practice in non-scientificwriting to use the term "calorie," with a lowercase c, when discussing the energy value of food.Estimating Calorieand Nutrient Needs
  • 2. When you see the term "calorie" in relation to diet and nutrition, it refers to the kilocalorie.Both calorie and kilocalorie are units of energy. To be precise:1 calorie = the amount of energy (heat) needed to raise 1 gram of water 1 degree Celsius. 1kilocalorie (Calorie) = the amount of energy (heat) needed to raise 1 kilogram of water 1 degreeCelsius.The fat in the foods we eat provides 9 calories per gram, alcohol provides 7 calories per gramand carbohydrate and protein each provide 4 calories per gram. This is why many healthprofessionals recommend cutting back on fat and empty calories from sugar or alcohol to aid inweight loss.Reducing fat, and sugar and alcohol intake may also reduce risk of heart disease, diabetes andcertain cancers. The type of fat you consume does make a difference. For example, olive andcanola oil are heart-healthy, while saturate and trans fat and detrimental. However, both typesof fat still contain the same amount of calories per gram.The calories (or energy) we consume from food are needed for breathing, metabolizing andabsorbing nutrients, maintaining body temperature, thinking and other physiologic functions,including exercise. To maintain body weight, calories you consume must equal calories youburn (through normal bodily functions and/or exercise). When excess calories are eaten andnot burned up by the body, the extra calories are stored as fat and result in weight gain. Whenfewer calories are eaten than are burned, weight loss is the result.You can estimate calorie requirements through a variety of formulas that are based on apersons:? Height? Weight? Age? Sex? Activity levelTherefore, everyones calorie requirements are different. In general, most individuals need aminimum of 1200 calories per day to maintain normal physiological functions. If you consumeless than this, your body may feel as though it is ?starving? and will lower your metabolism. Youwill also likely not consume enough calories to meet the RDAs for most nutrients. Very lowcalorie diets are not advised, though may be used by medical weight loss centers that aremonitored by medical personnel.How to Calculate Energy Needs
  • 3. Resting Metabolic Rate (RMR) A common formula used to estimate calorie needs is called theMifflin-St. Jeor Equation (named after the scientists that developed it). It is used to determine apersons RMR (metabolic rate). This represents the amount of energy (calories) the person usesfor basic bodily processes, such as breathing and maintaining blood pressure. The RMR doesnot take into account a person?s physical activity.The formula is as follows:Men: RMR= 5+10 (weight in kgs) + 6.25 (height in cms) ? 5 (age in years)Woman: RMR= 161+10 (weight in kgs) + 6.25 (height in cms)- 5 (age in years)Total Energy Expenditure (TEE) Your TEE, or total energy expenditure, is your RMR multiplied byan activity factor. This is the amount of energy you use during a normal day, including caloriesfor physical activity. To put this in context, your RMR reflects the calories you need to carry outnormal bodily functions such as breathing and maintaining body temperature. Your TEE takesinto account how active you are. Are you a couch potato, or a marathon runner?The TEE takes into account the extra calories your body needs to keep up with your dailyactivity. Exercise is the most variable way to adjust calorie needs. The more physically activeyou are, the more calories your body requires to maintain or gain weight. The followingexercise factors are used in calculating your calorie needs for weight maintenance:? 1.200 = sedentary (little or no exercise)? 1.375 = lightly active (light exercise/sports 1-3 days/week)? 1.550 = moderately active (moderate exercise/sports 3-5 days/week)? 1.725 = very active (hard exercise/sports 6-7 days a week)? 1.900 = extra active (very hard exercise/sports and physical job)Decreasing your physical activity level, or consuming more calories than your daily TEE will leadto weight gain. Increasing your activity level, or eating fewer calories than your body needs, willlead to weight loss. To lose 1 pound of weight per week, subtract 500 calories per day fromyour TEE. For example, if your maintenance needs are 2000 calories/day, you would need tolimit your intake to 1500 calories per day to lose.