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| Eating: Lean, Muscular, Weight Gain |
Using BMR and 'Daily Caloric Need' to Gain or Lose Body Weight.Let me start off by briefly going over some very basic, fundamental information about the constituents of the foods that we eat and how our bodies are able to utilize the calories, carbohydrates, proteins, and fats that make up these foods. All of the foods that we eat, including meats, vegetables and fruits are made up entirely of either one or more of the following 5 fundamental nutrients:
Of these 6 components, the first four in the list all contain calories. Calories are basically the amount of energy stored within each of these nutrients. Calories are needed by the human body to fuel metabolism. Metabolism is the process responsible for turning food into the energy needed to support life. The two basic metabolic pathways responsible for the conversion of calories to energy are the anabolic pathways and the catabolic pathways. Catabolism refers to the set of metabolic pathways in which molecules are broken down into smaller units causing a small amount of energy to be released in the form of heat, while the remaining energy is used to drive the synthesis of an energy transport molecule called adenosine triphospate (ATP). ATP is basically a molecular form of stored energy and allows the transfer of chemical energy from one metabolic process to another. The metabolic processes that use ATP as an energy source also convert it back into its precursors allowing it to be recycled continuously. The ATP, created during catabolism, is then available to fuel the processes within the other metabolic pathway - the anabolic pathway. Anabolism is the set of metabolic pathways reponsible for the construction of new molecules from smaller units. Anabolism is responsible for bone mineralization, cell differentiation and growth, and muscle growth. Regulating calorie intake can affect both gaining body weight and losing body weight. Generally consuming more calories than the amount used by the bodies' current metabolic needs results in body weight gain. Consuming fewer calories than the amount needed by the body to fuel its current metabolic needs results in weight loss. For someone interested in attempting to either gain or lose weight it is very useful to know how many calories are needed, on average, to fuel the bodies current metabolic needs. I will refer to this number as the 'daily caloric need'. To determine the 'daily caloric need' it is necessary to first ascertain what is called the BMR or 'basal metabolic rate'. The human body burns calories 24 hours a day, even during sleep. The basal metabolic rate, which can be estimated by using the very simple formula you see below, is the number of calories the resting body would burn if absolutely no activity were performed in a 24 hour period. Women: BMR = 655 + ( 4.35 x weight in pounds ) + ( 4.7 x height in inches ) - ( 4.7 x age in years ) Men: BMR = 66 + ( 6.23 x weight in pounds ) + ( 12.7 x height in inches ) - ( 6.8 x age in year ) Now that the BMR is known, applying an activity multiplier to this number will result in a fairly accurate estimate of the number of calories needed by the metabolism to fuel typiical activity level and basic metabolic processes. Here I am using the Harris Benedict Formula. To determine the 'daily caloric need', multiply the BMR by the appropriate activity factor, as follows:
Now that the 'daily caloric need' is known, it is very easy to figure out how many additional calories need to be consumed to gain weight or how many fewer calories need to be consumed to lose weight. For the person trying to gain weight, suffiiciently increasing calorie consumption over the 'daily caloric need' will cause body weight gain. A pound of body weight is roughly equal to 3500 calories, so if the goal is to gain one pound of body weight a week, 3500 excess calories should be consumed during the course of one week. Take 3500 and divide by 7 (days in a week), and the resulting 500 is the number of extra calories that need to be consumed each day to reach this goal. The composition of the calories consumed, ie. the amounts of proteins, carbohydrates and fats, is also very important to promote lean muscular gain. See the article, eating for lean, muscular, weight gain. When using this method to gain weight it is highly recommended that considerably more exercise should be performed to promote increased gains in lean muscle mass rather than increased storage of body fat. For someone trying to lose weight, a caloric deficit of 500 calories a day would result in a weekly deficit of 3500 calories and therefore a loss of one pound of body weight a week. The most effective way to lose weight is to combine calorie restriction with increased physical activity and exercise. Adding 30 to 45 minutes of cardio-vascular exercise (which typically burns between 300-500 calories) to the daily caloric restriction would result in a total calorie deficit approaching 1000 calories. Multiply that 1000 calorie a day deficit by 7 days for the week and the total weekly caloric deficit is now 7000. That works out to 2 pounds of body weight lost per week. Now it's important to remember that this is merely a guideline and many, many other factors can, and will produce great variation among the individual results realized through the use of this approach. Genetic factors, general health, a prior history of exercise experience and poor diet or nutrition can all contribute to a decrease in the effectiveness of this technique. It truly is not possible to emphasize enough the importance of consuming good high quality protein, adequate amounts of long chain complex carbohydrates and at least some omega-3 fatty acids, particularly while attempting to either lose or gain weight. More about this later. This discussion is continued in the next article. |