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.
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.