Total energy expenditure (TEE)

Calculate total energy expenditure from a basal energy expenditure multiplied by activity and stress factors.

What is this for?

Total energy expenditure is basal expenditure scaled up for physical activity and for the hypermetabolism of illness or injury. PharmCalc can either take a BEE you supply from any equation, or estimate one for you using Mifflin–St Jeor, which performs better than Harris–Benedict in contemporary populations.

How to use it

Either enter a basal energy expenditure you have calculated elsewhere, or select Mifflin–St Jeor and supply sex, weight, height, and age.
Choose an activity factor matching the patient's mobility, and a stress factor matching their clinical state.
Compare the result against the simple 25–30 kcal/kg/day estimates shown when a weight is supplied — a large divergence is worth investigating.

Worked example

A 55-year-old male, 70 kg and 175 cm, is on bed rest following skeletal trauma. Estimate his total energy expenditure.

Answer: Mifflin–St Jeor BEE = (10 × 70) + (6.25 × 175) − (5 × 55) + 5 = 700 + 1094 − 275 + 5 = 1524 kcal. TEE = 1524 × 1.2 × 1.3 = 2377 kcal/day, or about 34 kcal/kg.

Clinical pearls & pitfalls

Stress factors are historical multipliers derived from small studies, and modern critical care practice — sedation, ventilation, temperature control — has substantially reduced the hypermetabolism they were built to describe. Applying a 1.8 burn factor to a sedated ventilated patient generally overfeeds them.
Overfeeding is at least as harmful as underfeeding in critical illness, contributing to hyperglycaemia, hepatic steatosis, and difficulty weaning from ventilation.
Mifflin–St Jeor is more accurate than Harris–Benedict in modern populations, but both were validated in healthy adults, not in the acutely ill.
Simple weight-based estimates of 25–30 kcal/kg/day perform about as well as predictive equations in many critically ill patients and are far less error-prone. Use them as a cross-check.

Assumptions & limitations

Predictive equations have wide individual error, commonly ±20% or more against measured expenditure.
Activity and stress factors vary between references and institutions. The values offered here are representative, not authoritative — follow your local protocol.
Not validated in obesity, where equations based on total body weight substantially overestimate requirements. ASPEN recommends hypocaloric, high-protein feeding in obese critically ill patients.
Indirect calorimetry, not any equation, is the reference standard.

References

Mifflin MD, et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990;51(2):241-247.
McClave SA, et al. Guidelines for the provision and assessment of nutrition support therapy in the adult critically ill patient: SCCM and ASPEN. JPEN J Parenter Enteral Nutr. 2016;40(2):159-211.
Frankenfield D, et al. Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults. J Am Diet Assoc. 2005;105(5):775-789.