The ins and outs of metabolism

    When you think of metabolism what do you think of? A skinny guy eating nothing but junk food? A kid that eats nothing but processed foods and still being rail thin. That is exactly what it is. In simplistic terms it is the body's ability to break down food for metabolic functions. Metabolic functions are either the building up of smaller molecules into larger molecules (Anabolism) or the breakdown of larger molecules into smaller ones (catabolism) for energy. An example of anabolism (building up process) would be building muscle tissue while Catabolism (break down) would be the breakdown of food into energy. The total amount of these reactions is metabolism. 

    Factors such as genetics, age, body weight, body composition and training all play a factor into determining metabolism. Age and genetics are factors that a person has limited control over; while body composition, training, and body weight are factors that are controllable. 

    Altering body composition involves knowing how many calories it takes to sustain your bodies metabolic needs. BMR or basal metabolic rate accounts for roughly 65%-70% of your daily energy expenditure (total calories) and it is usually measured after an overnight fast. BMR is often referred to the least number of calories it takes to keep you alive. RMR or resting metabolic rate is more often used to since it does not require an overnight fast. Since it does not require a fast RMR is roughly 10% to 20% higher than BMR. To roughly calculate your RMR you could use the Cunningham equation. The Cunningham equation is simply 500+ 22 (LBM (Lean body Mass) in kg). Finding your lean body mass can be estimated through machines like a bod-pod or tools like Bioelectrical impendence analysis (BIA). BIA sends electrical signals through your body and since muscle is denser than fat the signals slow down thus giving results that take in account muscle tissue. Skin calipers are another option just keep in mind that locations vary amongst age, gender and race. Using skin calipers requires a trained user to ensure the most accurate data is presented. Tape measure is another effective tool to measure body fat. Typically, the neck and waist are used as locations. In either method a variance will exist. Skin Calipers has a +/- of 3-5%.

    In addition to RMR/BMR physical activity plays a factor into caloric intake. Typically, this can account for 20%-30%. The variance is dependent on the individual. It all depends on frequency, intensity and time associated with training. Furthermore, activity levels outside of exercise come into play. N.E.A.T or non-activity activity thermogenesis are the activities such as going on walks or doing laundry.

    The last pillar in the milking stool of metabolism is food thermogenesis. Food thermogenesis is the energy cost of digesting, absorbing, and storage of food in the body. Typically, this accounts for 10%-15% of total calories.