Practice Consideration
Weight Change
» Mr Robertson’s weight has been increasing at a rate of 2 kg per month for 6 months. He now weighs 90 kg up from 78 kg.
» Mr Robertson’s average daily energy intake during the 6-month period was estimated to be 3 227 kcal (12 974 kJ). See Activity 1.3 ii
Energy Intake
» Mr Robertson’s estimated energy requirement using:
— Simple Ratio Method* is 2 125 to 2 550 kcal (8 500 to 10 625 kJ) per day
— Mifflin St Jeor Equation** (Activity factor 1.4) is 2 344 kcal (9 842 kJ) per day
» The difference between his daily estimated requirements from the Simple Ratio Method and estimated intake is
677 to 1 102 kcal (2 349 to 4 474 kJ)
» In theory, if he reduced his intake by this amount per day he would experience weight maintenance, rather than ongoing weight gain
» If Mr Robertson’s weight had been stable and he consumed the lower estimated energy requirement of 2 125 (8 500 kJ) per day), the result might, in theory, be a weight loss of approximately 2.2 lb (1 kg) per month
Weight Change by Difference
» He has been gaining 4.4 lb (2 kg) each month for six months resulting in a 12 kg gain from 78 kg to 90 kg
» Theoretically there is 7 000 kcal (28 000 kJ) in each 2.2 lb (1 kg) of body weight.
This suggests that Mr Robertson is consuming 14 000 kcal (56 000 kJ) a month or 500 kcal (2 000 kJ) a day more than his requirements
» An energy reduction of 250 kcal per day (1 000 kJ per day) would, in theory, reduce his weight by 2.2 lb (1 kg) per month
» It is important to remember that energy requirement is influenced by factors including weight history, energy expenditure, musculature and energy intake
References
* Simple Ratio method is an equation based on the estimated amount of energy per body weight. It is usually expressed as Kcal/lb or KJ/Kg. A common example of simple ratio equations is found at https://www.health.qld.gov.au/__data/assets/pdf_file/0022/144175/est-req.pdf
**The Miflin St Jeor equation was developed and validated in the 1990's to predict estimated RMR based on a formula using height, weight, and age. A list of common formulas are found in the Evidence Analysis Library (free to Academy Members)