How much should you eat?
In order to decide how much you need to eat to fuel your body, we need to determine your basal metabolic rate, or BMR. Your BMR is the minimum amount of calories required to sustain the body’s functions and processes, when the body is at rest. Your BMR is responsible for burning up to 70% of the total calories you use during the day. Essentially, your BMR is the amount of energy your body needs just to function. Every function of your body requires calories/energy for fuel. Functions such as breathing, maintaining your body temperature, and breathing all require energy. Obviously, you will burn more calories on top of what is used for your BMR depending on various factors.
The following factors will influence your BMR:
· Genetics
· Gender: Men generally have more muscle and less body fat than women, which makes them have a higher BMR
· Age: Your BMR will drop about 2% per decade after the age of 20
· Weight: The more you weight, the higher your BMR
· Height: The taller you are, the greater your BMR
· Body Fat: The lower your body fat percentage, the higher your BMR
· Diet: Very low calorie and restrictive diets will drastically reduce your BMR by up to 30 percent. This is why it is counter-produce to excessively restrict calories in order to lose weight.
· Exercise: exercise not only influences body weight by burning calories, it also raises your BMR. Exercise causes you to have more lean tissue and muscle so that you burn more calories when at rest
There are also some short term and transient factors that will affect your BMR. High fevers, stress and temperature increase will increase your BMR.
How to calculate your BMR
The first step in designing a personal nutrition plan is to calculate your BMR so that you know how many calories you will burn per day at rest. We need to know what your “total daily energy expenditure (TDEE)” is. TDEE is the amount of calories your body expends per day, including all activities. (BMR is how many calories, your body burns at rest. TDEE is the TOTAL of calories burned factoring in all activity).
A quick and easy way to determine calorie needs is to use total current body weight times a multiplier.
For fat loss = you will need 12-13 calories per pound of body weight
To maintaine your current status (TDEE) = consume 15-16 calories per pound of bodyweight
For weight gain = consume 18-19 calories per pound of bodyweight
This is an easy method to estimate caloric needs, but there are drawbacks to this method, mainly that it doesn't take into account activity levels or body composition.
Highly active individuals will require more calories than this formula indicates. In addition, the more lean body mass one has, the higher the TDEE will be. Because body fat levels are not accounted for, this formula may greatly overestimate the caloric needs if someone is extremely overfat. For example, a lightly active 50 year old woman who weighs 235 pounds and has 34% body fat will not lose weight on 3000 calories per day (235 X 13 as per the "quick" formula for fat loss).
A commonly used formula to figure out BMR is using the Harris-Benedict principle. This formula can be a bit more accurate, and this is the formula that I recommend you use:
Women: 655 + (4.3 x your weight in pounds) + (4.7 x your height in inches) – (4.7 x your age in years)
Men: 66 + (6.3 x weight in pounds) + (12.9 x height in inches) – (6.8 x age in years)
For example: To figure the BMR for a 5’ 4”, 150 pound, 30 year old woman: 655 +(4.3x 150) + (4.7 x 64) – (4.7 x 30) which equals to 1459
This equation will be very accurate for most people, except for those who are either very muscular or very over-fat.
So, at this point, go ahead and figure out your BMR. You should write it down for reference, as this will be your starting point in figuring out your meal plans.
Tomorrow, we will discuss the Body Mass Index. See you then.
