Calculating Caloric Requirements in Pediatric Obesity
For pediatric obesity, calculate resting energy expenditure (REE) using the Schofield equation based on weight and height, then create a 500-750 kcal/day deficit from maintenance needs, ensuring intake never falls below 900 kcal/day minimum under medical supervision. 1
Step-by-Step Calculation Algorithm
Step 1: Calculate Baseline REE Using Schofield Equation
Use the age- and sex-specific Schofield equations, which are the preferred method for calculating REE in pediatric populations 2:
For ages 3-10 years:
- Boys: REE (kcal/day) = 22.7 × (weight in kg) + 504 2
- Girls: REE (kcal/day) = 20.3 × (weight in kg) + 486 2
For ages 10-18 years:
- Boys: REE (kcal/day) = 17.7 × (weight in kg) + 658 2
- Girls: REE (kcal/day) = 13.4 × (weight in kg) + 692 2
The Schofield equation using both weight and height is least likely to underestimate REE compared to measured values and is therefore the preferred calculation method 2.
Step 2: Adjust for Physical Activity Level (PAL)
Multiply the calculated REE by an appropriate physical activity factor 2:
- Sedentary/hospitalized: PAL = 1.2-1.3 2
- Light activity: PAL = 1.5 2
- Moderate activity: PAL = 1.7 2
- Vigorous activity: PAL = 2.0 2
Most children with obesity have reduced physical activity levels, so a PAL of 1.3-1.5 is typically appropriate 2.
Step 3: Add Energy Cost of Growth
Include additional calories for normal growth, which varies by age 2:
- Ages 6-12 months: 20 kcal/day 2
- Prepubertal children: 20 kcal/day 2
- Peak pubertal growth velocity: 30 kcal/day 2
This ensures adequate energy for continued development even during weight management 1.
Step 4: Create Appropriate Caloric Deficit
Subtract 500-750 kcal/day from the calculated total energy expenditure (TEE = REE × PAL + growth) to achieve weight loss of approximately 0.5 kg (1 pound) per week 1. This deficit preserves lean body mass during growth and ensures adequate micronutrient intake 1.
Step 5: Apply Minimum Caloric Floor
The final calculated intake must never fall below 900 kcal/day for children ages 6-12 years when under close medical supervision 1. This absolute minimum prevents growth impairment, micronutrient deficiencies, hormonal disruption, and psychological harm 1.
Critical Considerations for Obese Children
Which Body Weight to Use
Use actual body weight in the Schofield equation 2. The equations were developed using actual weight, and body weight is the main predictor of energy expenditure 2. Research demonstrates that when body weight is considered, overweight and obese children do not differ from normal-weight counterparts in energy expended for basal metabolism or physical activity tasks 3.
Validation in Obese Populations
Predictive equations show significant variability in obese youth, with potential errors ranging from 198-308 kcal/day 4. The Harris-Benedict, Lazzer, and Molnar equations provide the greatest accuracy (60-65%) in severely obese youth, but indirect calorimetry remains preferred when available 4. New obesity-specific equations using fat-free mass show improved accuracy (R² = 0.76-0.79) 5.
When to Use Indirect Calorimetry
Measure REE using indirect calorimetry in children with suspected metabolic alterations, severe malnutrition, or when initial weight management approaches have been unsuccessful 2, 6. Indirect calorimetry is the reference standard and most accurate measure of energy needs 2.
Common Pitfalls to Avoid
Never Use Very-Low-Calorie Diets
Very-low-calorie diets (≤800 kcal/day) are explicitly contraindicated in children and adolescents due to risks of growth impairment, micronutrient deficiencies, hormonal disruption, and psychological harm 1. Even the 900 kcal/day minimum requires close medical supervision 1.
Don't Rely on Caloric Restriction Alone
Comprehensive intervention must include structured behavioral modification, family involvement, physical activity programming, and regular self-monitoring 1. A registered dietitian nutritionist should design the meal plan addressing age-appropriate portion sizes, cultural food preferences, and family eating patterns 1.
Avoid Using Separate Equations for Obese vs. Normal Weight
Despite the existence of separate IOM equations for overweight/obese children, there is no theoretical rationale for having two sets of equations based solely on body-weight classification 3. Energy needs for weight maintenance predicted using obesity-specific equations show inconsistent results between boys and girls 3.
Monitor for Metabolic Complications
Adjust the nutrition regimen based on outcomes such as hyperglycemia, growth velocity changes, and other metabolic disturbances 2. Clinical staff should review individual nutritional requirements regularly as patients' needs can frequently change 2.
Dietary Composition Requirements
Despite caloric restriction, ensure a nutritionally balanced diet with 1:
- Moderate fat intake with adequate protein
- Carbohydrates from whole grains and fiber-rich sources
- Nutrient-dense, low-energy-density foods
- Elimination of liquid calories and limitation of added sugars, sodium, and highly processed foods
Expected Outcomes and Follow-Up
With appropriate caloric restriction and comprehensive lifestyle intervention, expect 1:
- BMI reduction: approximately 1.18 kg/m² over 6-12 months
- Weight loss: 3-4 kg over the intervention period
After initial weight loss, transition to a weight maintenance program focusing on normocaloric-eucaloric diet, continued physical activity, and ongoing behavioral support with family involvement 1.