Energy Deficit Calculation

Based on Mifflin-St Jeor Equation
Males Resting Energy Expenditure
1. Start: 10 x (Weight in kilograms) + 5
2. Add: 6.25 x (Height in centimeters)
3. Subtract: 5 x (Age in years)
Females Resting Energy Expenditure
1. Start: 10 x (Weight in kilograms) - 161
2. Add: 6.25 x (Height in centimeters)
3. Subtract: 5 x (Age in years)

Consider Activity factor (AF) of 1.0
1. AF >1.0 grossly overestimates caloric needs
2. Using activity factor of 1.0 may be weight neutral
  1. Mucha (2007) HP Primary Care Medicine, Lecture
  2. Bezera (2001) J Amer Dietetic Assoc 101 [PubMed]
Determine Daily Caloric Need
1. Resting Energy Expenditure x Activity Factor
2. See Daily Energy Allowances
3. Moderately active adolescents (e.g. teen athletes) may have high energy requirements to sustain activity, growth
  1. Females may require 2200 kcals/day, while males may require 2800 kcals/day

Determine daily caloric deficit (typically 250 to 500 kcals/day)
1. Deficit of 500 Kcals/day = 3500/week (1 pound/week)
2. See precautions below regarding over-estimation of weight loss with 3500 calorie/pound rule
Determine Adjusted Caloric Intake
1. Daily Caloric Need - Daily caloric Deficit (500)
2. Do not lower intake below 1000 Kcals/day
3. Consider using REE x0.8 for weight loss program
  1. Mucha (2007) HP Primary Care Medicine, Lecture
  2. Bezera (2001) J Amer Dietetic Assoc 101 [PubMed]
4. Consider calorie intake goal based on body weight range
  1. Body weight <200 pounds: 1000 Kcals/day (500 kcal deficit per day)
  2. Body weight 200-249 pounds: 1200 Kcals/day (750 kcal deficit per day)
  3. Body weight 250-299 pounds: 1500 Kcals/day (1000 kcal deficit per day)
  4. Body weight 300-349 pounds: 1800 Kcals/day (1250 kcal deficit per day)
  5. Body weight >350 pounds: 2000 Kcals/day (1500 kcal deficit per day)
  6. Klein (2002) 123(3): 882-932 [PubMed]

Weight loss estimates based on 3500 calorie deficit per pound weight loss will markedly overestimate loss
1. Naive weight loss approximation with 3500 calorie rule (due to compensatory mechanisms)
For every 100 calorie deficit, expect 10 pound weight loss over time
1. Year 1: Weight loss of 50% of total estimate (5 pounds per 100 calorie deficit/day)
2. Year 3: Weight loss of 95% of total estimate (9.5 pounds per 100 calorie deficit/day)
Resources
1. FPnotebook Resting Energy Expenditure Calculation
2. NIH Body Weight Simulator
  1. http://www.niddk.nih.gov/research-funding/at-niddk/labs-branches/LBM/integrative-physiology-section/body-weight-simulator/Pages/body-weight-simulator.aspx
References
1. Lesser (2015) Am Fam Physician 91(9): 634-8 [PubMed]