Estimating Nutritional Requirements In Clincial Practice

Question 1

Components of TDEE and SACN definition of energy requirements in healthy population

Answer 1

• BMR: 60-70%, 5-10% variance between individuals, can be measured by indirect calorimetry
• DIT: 10% for a mixed meal, more if high in protein
• PA: ~25-50%. Most variable component, can be measured by accelerometers
• SACN defines a healthy person’s energy requirements to be that which allows them to maintain a healthy body weight at current levels of activity

Question 2

How measured energy expenditure changes in disease and factors which affect this

Answer 2

• EE stays about the same as although activity is greatly reduced, BMR is greatly increased
• factors affecting this BMR increase include: inflammation, age, gender, type of illness, severity of illness, metabolic state (catabolic), nutritional statis, medical interventions (surgery), psychological state, physical activity

Question 3

Impacts of malnutrition and what are the goals of nutritional support

Answer 3

• malnutrition can be caused by EI assessment of severity> treatment (dietary counselling, ONS, enteral/parenteral nutrition, supportive interventions)> monitoring

Question 4

Different methods of estimating energy requirements and criticisms

Answer 4

• indirect calorimetry: not very practical for everyday practice
• factorial method (PENG 2011): involves estimating BMR, adjusting for metabolic stress, adjusting for activity and DIT, and add/subtract for weight change. But BMR equations derived from healthy populations, very old equations (1919), inappropriate stress factors not specific for individual, doesnt account for advances in clinical management meaning patients are less stressed, too static
• regression equations: using equations matching specific patient populations. But no guidelines on when to review/how frequently to review, how applicable is this to each individual patient?
• rule of thumb method (recommended by NICE in 2006): 25-35kcal/kg/day. But we dont know which figure to use, and it is unclear of adjustments to be made at extremes of BMI, no accounting of changes to EE depending on age and gender

Question 5

2019 PENG guidelines for nutritional support (including energy and protein requirements)

Answer 5

• for energy requirements, need to establish goals of treatment (minimise weight loss? Weight gain? Weight maintenance?). Then use 4-step rule of thumb method for EE, and add combined factor for DIT and PA. Monitor response to treatment. Includes an adjustment for those at extreme ends of BMI
• protein requirements: 1-1.5g/kg/day

Question 6

What influences protein requirements in older people?

Answer 6

• decreased intake due to: physiological changes, genetic predisposition, clinical condition, disability, psychological/ socio-economic issues
• decreased ability to use protein: down-regulated anabolic response, inflammation and catabolism, sarcopenia, decreased muscle perfusion, decreased amino acid availability