A healthy lifestyle blog by ACE Certified Group Exercise Trainer.

How many calories do you need?

In order to lose weight, your calorie intake must be less than your total daily calories burned. In order to figure that number out, you'll need to start by calculating your resting metabolic rate.

The following info is from ACEfitness.org, the American Council on Exercise.

What Is Resting Metabolic Rate? 
BMR and RMR are estimates of how many calories you would burn if you were to do nothing but rest for 24 hours. They represent the minimum amount of energy required to keep your body functioning, including your heart beating, lungs breathing, and body temperature normal.
  • BMR stands for Basal Metabolic Rate, and is synonymous with Basal Energy Expenditure or BEE. BMR measurements are typically taken in a darkened room upon waking after 8 hours of sleep; 12 hours of fasting to ensure that the digestive system is inactive; and with the subject resting in a reclining position.
  • RMR stands for Resting Metabolic Rate, and is synonymous with Resting Energy Expenditure or REE. RMR measurements are typically taken under less restricted conditions than BMR, and do not require that the subject spend the night sleeping in the test facility prior to testing.

These are used to determine your Total Daily Energy Expenditure  
TDEE = RMR + TEF + NEAT + EPOC + Ex 
How Do I Calculate RMR?
There are two main ways to determine how many calories you burn in a given day. A relatively accurate (but more difficult) method is called indirect calorimetry, which uses expired gases to calculate the amounts and types of fuel being utilized.
A less accurate, but much easier, method for determining RMR is to use one of several different formulas. Keep in mind, however, that some sources claim these formulas can be off by as much as 1,000 calories, with the majority of error or variation occurring in the calculation of daily energy expenditure. Several websites, including Health-calc, make it possible to more accurately record daily activity, which can increase the accuracy of the RMR calculation.

RMR Formulas in Action
Following are sample calculations for a 48-year-old woman who is  165 cm (5’5”) and weighs  75 kg (165 lb) using several popular RMR equations. 
* Revised Harris-Benedict BMR Equations (calories/day):
Male: (88.4 + 13.4 x weight) + (4.8 x height) – (5.68 x age)
Female: (447.6 + 9.25 x weight) + (3.10 x height) – (4.33 x age)
weight in kilograms, height in centimeters, age in years
Sample: 447.6 + 9.25 x 75 + 3.10 x 165 = 1,444 calories
* A more accurate formula is the Mifflin-St Jeor Equation(calories/day):
Male: 9.99 x weight + 6.25 x height – 4.92 x age + 5
Female: 9.99 x weight + 6.25 x height – 4.92 x age – 161
weight in kilograms, height in centimeters, age in years
Sample: 749.25 + 1031.25 – 236.16 = 1,544.34 calories
For highly athletic clients, the Katch-McArdle equation (BMR) and the Cunningham equation (RMR) are better because they consider lean muscle mass.

What is TDEE and why is it important?
Exercise is easily the most adjustable variable in total daily energy expenditure. Some sedentary people expend just a little bit above their RMR in a given day, while others can more than double it. The following list defines various activity levels and applies an “activity factor” that can be multiplied by BMR or RMR to calculate TDEE. 
·         Sedentary — desk job and little to no exercise (multiply by 1.2)
·         Lightly Active — light exercise/sports 1–3 days/week (multiply by 1.375)
·         Moderately Active — moderate exercise/sports 3–5 days/week (multiply by 1.55)
·         Very Active — hard exercise/sports 6–7 days/week (multiply by 1.725)
·         Extremely Active — hard daily exercise/sports and physical job or training (multiply by 1.9) 
So for our 48 year old woman – if she is lightly active (maybe she walks 3 days a week) we would multiply her RMR by 1.375  or 1544.35 x 1.375 = 2123 total daily energy expenditure. So our lady can consume 2123 calories per day to maintain weight. She should subtract 500 per day if she wants to lose a 1lb per week.

What Variables Affect Metabolic Rate?
You might find a few observations about them interesting:
·         When your age goes up, your BMR and RMR go down.
·         When your height goes down, your BMR and RMR go down.
·         When your weight goes down, your BMR and RMR go down.
This means that as you get older, shorter, and lose weight, your BMR and RMR will go down and you will need to eat less or exercise more to maintain your current weight. Oh my, it's tough getting old. At least as we get older we get wiser. Well, hopefully.

What Are the Best Exercises For Raising Metabolic Rate and Losing Weight?
Unfortunately, this question does not have one simple answer and research has shown conflicting results (Connolly, Romano and Patruno, 1999). Currently, high-intensity interval training (HIIT) appears to be a leading contender for the title of best RMR enhancer, and the exercises that build muscle (i.e., resistance training) are believed to have the greatest effect on the resting metabolic rate. It is worth noting that hypertrophy-focused workouts, with high resistance to maximize muscle building, don’t burn a high number of calories and, likewise, the EPOC is small. A proper HIIT approach, however, which involves raising the heart rate and calorie expenditure to a high level and results in a significant EPOC, may be one of the most effective methods of increasing RMR. 

What Does Reducing Caloric Intake Do to RMR?
For a personal trying to lose body fat, one of the worst things he or she can do is cause a major drop in RMR by fasting from eating. Studies show that RMR can often be maintained on very-low-calorie diets (VLCD) when sufficient exercise is sustained (van Dale, Saris and ten Hoor, 1990). However, if an individual goes on a VLCD without exercise, RMR will be reduced dramatically and muscle tissue will likely be catabolized as a source of protein for ketosis to occur. Therefore, to achieve weight loss while also maintaining RMR, calorie intake should be reduced by no more than 500 calories per day, while exercise expenditure should be account for approximately 250 to 1000 calories per day. 

Skip the mathwork and figure your TDEE out at http://iifym.com/tdee-calculator/

References
www.acefitness.org
Connolly, J. Romano, T. and Patruno, M. (1999). Effects of dieting and exercise on resting metabolic rate and implications for weight management.Family Practice, 16, 2, 196–201.
Johnstone, A.M. et al. (2005). Factors influencing variation in basal metabolic rate include fat-free mass, fat mass, age and circulating thyroxine, but not sex, circulating leptin or triiodothyronine. American Journal of Clinical Nutrition, 82, 5, 941–948.
van Dale, D., Saris, W.H., ten Hoor, F. (1990). Weight maintenance and resting metabolic rate 18–40 months after a diet/exercise treatment. International Journal of Obesity, 14, 4, 347–359.


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