A. Everybody's metabolism responds differently to
various stimulus. However, there is the Basil Metabolic Rate
(BMR) which can generally predict how many calories our
body burns at rest. To lose weight we would need to create a
deficit by consuming less and burning calories. To gain weight
we would increase our caloric intake and strength train to increase lean muscle tissue. Although the BMR isn't always 100 percent accurate, it is a great way to start a nutrient intake program. You can then increase your caloric intake if you find yourself lethargic by manipulating your carb, protein and fat intake. You decrease your caloric intake if you find you are still not losing fat and your energy and brain functions aren't compromised.
BMR: Your Basal Metabolic rate is the amount of energy that your body "burns" in a 24-hour period while doing absolutely nothing. If you were seated on your couch, watching TV for 24 hours, you would burn the equivalent of your BMR in calories. It's possible to estimate your BMR from a formula. Obviously, this wont be 100% accurate, but it gives you a pretty good idea of what your body needs to function.
These formulas are:
MEN:
BMR = 66 + (6.23 X weight in lbs) + (12.7 X height in inches) — (6.8 x age)
WOMEN:
BMR = 655 + (4.35 X weight in lbs) + (4.7 X height in inches) — (4.7 x age)
For Example, let's take myself.....
BMR = 66 + (6.23 X 220lbs) + (4.7 X 70 inches) - (4.7 X 47)
= 66 + 1,370.6 + 329 - 220.9
= 1,554.7 calories per day
I would burn 1,554.7 calories in a 24-hour period, while doing absolutely nothing.
Once you have established your BMR you can then gradually decrease your caloric intake and increase your caloric burn by performing cardio and strength training workouts to reach your weight loss. Keep in mind this is a general formula and may be influenced by medications or pre-existing medical conditions such as hypo or hyper thyroidism etc.