A How-To Guide For Calculating Your Nutritional Needs

Let me preface this article by saying that I am NOT a licensed dietitian. In the ensuing text I will detail the specifics of nutrition as it relates to maintaining, losing, and gaining weight.

This information is taken from the accepted evidence supplied by the NSCA and CISSN. Be sure to consult a licensed professional before undertaking new dietary practices. I will not give you a specific meal plan nor tell you how to eat for your body. This is out my scope of practice. I want you to have the best information to make the most accurate, evidence based decisions possible.

After reading this I hope you can walk away with the education and the confidence to calculate your own nutritional needs and structure an eating regimen that caters to your lifestyle.

Now…Let’s roll.

Energy Expenditure

Energy requirements will depend largely on factors including genetics, bodyweight, body composition, training program, and age.

Basal Metabolic Rate (BMR) is the largest contributor to your total daily energy expenditure, accounting for 65-70% of daily energy expenditure. This is a measure of the calories required for maintaining normal body functions including respiration, blood circulation, and gastrointestinal and renal processing.

You may see BMR and resting metabolic rate (RMR) used interchangeably. They are slightly different, but for the sake of this article I will use RMR moving forward. Essentially, BMR is measured after an overnight fast (12-14h) with the person resting supine and motionless, but awake. The RMR is used more frequently because of its ease of measurement. No overnight fast is required, yet it will read 10-20% higher than BMR due to the energy expenditure from recent food intake or physical activity done earlier in the day.

The second biggest component of energy requirement is the energy expended during physical activity. This will vary considerably and increase with intensity, frequency, and duration of exercise. Non training activities such as doing the dishes or yard work will also contribute to energy requirements. Typically 10-20% of total daily energy expenditure (TDEE) is from physical activity.

Lastly, the thermic effect of food (TEF) accounts for the remaining 10-15% of TDEE. This factors in the cost of digestion, absorption, metabolism, and storage of food in the body.

The Cunningham Equation

If you take away just one thing from this article it should be this equation…


LBM or Lean Body Mass is calculated using kilograms. Subtract your body fat percentage from your current weight to find this.

Using myself as an example:

Weight: 205 lbs / 2.2 = 93 kg
BF: 14%
14% of 93 = 13 kg
RMR = 500+22(80) = 2,260 kcal

RMR should then be multipled by an activity factor from 1.2 (sedentary) to 1.9 (heavy physical activity).

This gives me a calorie range from 2,712 – 4,294 kcal.

Okay! No more math. That was exhausting.

Here’s a general recommendation for calculating your activity factor…

1.1-1.2 (Minimally active, <1000 steps/day)
1.3-1.5 (Moderately active, train 2-3x/week, 4000-6000 steps/day)
1.5-1.7 (Highly active, train 4-5x/week, 8000+ steps/day)
1.7-1.9* (Demanding physical job, train 5+/week, >10,000 steps/day)

*Unless you are an olympic athlete or do extremely demanding work and exercise then you probably don't fit into the category. 

Keep in mind that the majority of us mortals belong in the sedentary to moderately active range. Even if you exercise everyday for an hour you’re likely still sedentary for the majority of the day. Food for thought.

Gaining Weight

After establishing your initial calorie requirements this should be a breeze.* The general principle is to increase your calories between 250-500 per day to elicit weight gain.

It is more beneficial to start with small increases at the risk of gaining weight too quickly which will result in excess fat being stored on the body. If you’re in a place where you need to gain weight–congrats! You are contrary to a good 75% of the population that now hates you.

Just kidding.

But they are jealous. Getting to eat more is usually** a nice problem to have.

Weight Loss

Okay–so you don’t need to gain weight. Instead, you want to shed some excess body fat. Despite the diet books being touted at your local Barnes and Noble, there is no ideal diet that works for everyone.

Studies consistently show that a multitude of diets , including low-carb and low-fat diets, result in weight loss as long as people don’t eat like an asshole are consuming less calories than they need to maintain bodyweight.

The two strongest contributors to weight loss are total calorie intake and diet adherence.

Please do not fall for these diet traps promising you fast results with a “revolutionary” eating approach. You’re better than that.

The best, most sustainable approach is what can be called the “low and slow”. Eat in a moderate calorie deficit of 250-500 calories and you’ll see far greater results.

*And by breeze I mean one of the strong gusts of wind that'll take your eyebrows off.
**Unless you are Joey Chestnut. That's an alarming amount of hot dogs for one person. 

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