The Mathematics of Nutrition

When it comes to proper nutrition, knowing what to eat is half the battle. The other half is knowing how many calories you should be eating. The average calorie consumption values for young women are 2000 calories/day and for men 3000 calories/day. I would not recommend basing your own calorie consumption off of these because every body is unique and some days more energy is expended than others.

There are two formulas that are used to calculate basal metabolic rate (BMR) and resting metabolic rate (RMR). Your BMR is the amount of calories that your body needs to maintain vital functions. RMR is how many calories your body would need to maintain vital functions along with digestion of food (this value is usually 10-20% higher than BMR). Metabolic rates vary with gender, age, body size, and the amount of fat free body mass. They are absolutely different for everyone!

To calculate your own BMR here are two formulas:


294 – (3.8 x age) + (456.4 x height) + (10.12 x weight)


247 – (2.67 x age) + (401 x height) + (8.6 x weight)

** convert height in inches to meters (inches x 0.0254) and weight in pounds to kg (pounds/2.2) **

If you don’t have time to do it by hand, you could Google BMR calculator and there are a number of fairly reliable websites that will do the work for you! You could even try a few of them to determine a consistent calorie count.

Once you know your own personal basal metabolic rate, you are one step closer to finding out your total daily energy expenditure (TDEE). This value is the amount of calories you expend in one day. It takes into account your BMR – 65%, thermic effect of food – 10% (how many calories it takes your body to process and store food that you’ve eaten) and energy expenditure from physical activity that day – 25%. There is a lot to consider, so lets continue on.

An easier way to track your estimated TDEE would be to add your BMR to the amount of calories you burned through physical activity and exercise. A simple rule of thumb is that walking or running 1 mile will burn around 100 calories. I use this rule when I factor in how many miles I walk per day. As exercise varies, so does the amount of energy expenditure. The amount of calories burned depends on intensity (how hard you’re pushing yourself), mode (what are you doing), frequency (how often you do it) and duration (how long are you doing it). Personally, my workouts vary from day to day so it is hard for me to estimate how many calories I burned. I try not to eat much more than my BMR estimates, unless I have a particularly hard or long workout that day.

So now that you have your own personal energy expenditure value, it is very important to remember to use your calories wisely by filling your belly with fruits, vegetables, whole grains, lean meats and other proteins. In general, the guidelines for macronutrient consumption (protein, fats, and carbohydrates) are as follows:

Carbohydrates should constitute about 60% of total calories for an active adult

Fats should constitute less than 30% of total calories for all adults, and the majority of those fats should be unsaturated!

Protein should constitute 15-20% of total calories for adults, but this value does increase based on strength or endurance training.

I know this is a lot of information to get through, but thank you for sticking with me! Our baby steps are building one by one 🙂

P.S. don’t forget those New Years Resolutions!

“Every time you eat is an opportunity to nourish your body.”

With Love,


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