How many calories do you need?
BMR is your basic metabolic rate, which is the amount of calories your body needs just to function if you were in bed all day.
You do not want to subtract from the resting metabolic rate because that is the minimal amount without any exercise.
You would calculate the daily caloric need with activity level
Then calculate the caloric deficit
Then take away the calorie deficit from the caloric total
This leaves you with the daily amount of calories the person should consume.
Here is an example:
Let’s consider that a woman, based on the Mifflin-St. Jeor equation, needs 2450 calories/day to maintain her weight. Let’ say that she needs to lose weight and she agrees to lose 1 lb/week. She also agrees to exercise 3 times a week. For the sake of arguing let us talk about the nutrition part of the situation. I would love to understand in a practical way how to quantify this for a client. How do I create the deficit for her and ensures that she gets the amount that she needs to get?
We will call the lady Sarah
Based on Sarah’s daily average expenditure she requires 2450 calories per day to maintain her weight. That is, she would eat 2450 calories a day and maintain the same activity level.
Let’s say Sarah wants to lose 20 pounds in 20 weeks. This equals 1 lb per week of weight loss. Completing the Calorie deficit calculation, means she needs a calorie deficit each day of 500 calories.
20lb x 3500 (amount of calorie deficit to lose 1 lb of fat)
= 70,000 calories
70,000 ÷ 20 weeks = 3500 calories per week
3500 ÷ 7 days = 500 calorie deficit per day
Sarah needs to create a daily deficit of 500 calories. This is best worked out as a deficit of 250 calories from food (i.e. remove 250 calories from her diet) and 250 calories from exercise (burn 250 calories during exercise).
Because Sarah is not going to exercise every day, let’s use two different days as an example, as you said she wants to exercise only 3 days per week.
DAY 1 – reduce diet by 500 calories as no exercise on this day.
DAY 2 – reduce daily diet by 250 calories and burn 250 calories through exercise.
DAY 1 – 2450 – 500 calories = 1950.
Sarah must only eat 1950 calories per day on the day she does not exercise.
Then Sarah can create a diet for herself while “counting” the amount of calories up to the 1950 established amount.
DAY 2 – 2450 – 250 calories = 2200 of calories she can eat in a day
She must burn 250 calories to bring her down to the calorie total of 1950.
Diet – using above methods, Sarah creates a diet for herself allowing an intake of 2200 calories per day
You can use these calculators to estimate the calorie expenditure.
Physical Activity Calorie Counter http://www.acefitness.org/acefit/healthy_living_tools_content.aspx?id=9#sthash.sTxTS4sY.dpbs
You will not be able to calculate an exact calorie expenditure for Sarah as this requires expensive lab equipment.
An example workout for Sarah to burn 250 calories:
(Let’s say Sarah is 150 lbs) http://www.acefitness.org/acefit/healthy_living_tools_content.aspx?id=9#sthash.sTxTS4sY.dpbs
Running for 20 minutes at 6mph she will burn approx. 227 calories
+ 20 minutes of weight training = 68 calories.
Total calories burned = 295 calories.
Losing weight is a very simple math equation of the energy output needs to be greater than energy input.
Let’s say Sarah has a 500 calorie coffee with whipped cream and eats a daily morning donuts. Instead of counting all of her daily calories, she could simply implement holding the remainder of her daily foods stable and removing those two high calorie foods each day.
Or maybe she could change some of the foods she eats each day, instead of fried chicken, she could grill the chicken, instead of mashed potato with butter and cream, she could try a sweet potato. There are many ways you can help to make a diet more healthful and less calorie dense without counting calories.
But remember, not all calories are created equal. If you eat the right number of calories you need to lose weight but eat all junk, you will have less energy and motivation, leading to lower caloric expenditure and weight gain/maintenance. The key is to find balance. Eat foods that wont spike insulin levels, and aim for nutritious foods high in vitamins, rather than whatever hits your macro nutrient needs. You can use this calculator to find out what your macro breakdown should be.