If you want to lose weight, the formula is simple…create an energy imbalance by increasing the amount of calories you burn and/or decreasing the amount of calories you intake. This sounds “easy” however there are many other factors that can effect the rate at which you burn calories…here it is general terms:
Your overall metabolism or “Total Energy Expenditure” refers to how many calories you burn in a 24-hour period. Your overall metabolism has three main components:
(1) ~60% Resting Metabolic Rate – RMR is the number of calories your body needs to simply function. It is determined by your age (as you grow older you begin to lose muscle mass and therefore burn fewer calories), sex (men naturally have more muscle, they burn more calories), and body type (for example, those with more muscle tend to burn more calories, and fit muscles burn calories even while at rest). Other factors effecting RMR include genetics, organ activity and organ size. Both long-term participation in aerobic exercise and resistance exercise have shown to somewhat independently increase RMR.
To find your estimated RMR, try using the Mifflin-St. Jeor Resting Metabolic Rate equation:
*Find your weight in kilograms by dividing your weight in pines by 2.205
*Find your height in centimeters by multiplying your height in inches by 2.54
Males: 10 x (weight in kg) + 6.25 x (height in cm) – 5 x (age in years) + 5
Females: 10 x (weight in kg) + 6.25 x (height in cm) – 5 x (age in years) – 161
(2) ~10% Thermic Effect of Food – This is the amount of calories used in the digestion, absorption and metabolism of nutrients within your body. This typically does not fluctuate much.
(3) ~30% Thermic Effect of Exercising and Spontaneous Activity – If you are trying to make a calorie deficit, this is the portion of your total energy expenditure that you have the most control over. By exercising more or just increasing daily tasks (for example, taking the stairs instead of the elevator) you will overall burn more calories.
Helpful Tool…
This calorie calculator utilizes the above-mentioned RMR formula and adds into account typically weekly activity level: Calorie Calculator
It’s important to remember that without an individual metabolic assessment, any calculation method will only be a ‘best estimate’.
*the widely recognized Mifflin-St. Jeor RMR equation has a +/-10% accuracy
What This Means for YOU…
Your body will automatically balance your metabolism for what it needs on a daily basis. If you go on an unhealthy diet and don’t get enough calories and nutrients, your body automatically uses survival tactics and begins to hold on to whatever calories it has available. Often times dieting can push the body into a “starvation mode” which can actually lead to eventual weight gain.
It is possible that overall metabolism, more specifically RMR, can be effected by factors such as heredity hormonal imbalances, etc. however it is most likely that weight gain is not caused by a slow metabolism, but more commonly by consuming more calories than you actually need for daily activities. If you feel like you are maintaining a good diet and exercise regimen but your weight loss goals still have not been accomplished – make sure you have given it enough time but always defer to your physician if you suspect it is a health-related obstacle.
In the end, the weight loss formula really is simple…create an energy imbalance by increasing the amount of calories you burn and/or decreasing the amount of calories you intake. Make sure you are eating a well-balanced diet full of healthy food choices so you can obtain the necessary nutrients your body needs, and are staying active and exercise (both cardio and strength) on a daily basis.
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