Scientific Macro Calculator
Information & Literature
The Formulas
Its worth making a point here that none of these formulas will give everyone who uses it the same level of accuracy, nor should they be used more than just a starting point, to then make adjustments from depending on where your body composition goes in relation to the goals you have set. Below im going to show you what the formulas are mathematically, point you towards where they came from then talk about their suitability and limitations.
Harris-Benedict (Revised) - 1984
Female: ( 9.247 * Bodyweight) + (3.098 * Height) - (4.330 * Age) + 447.593
Mifflin St Jeor - 1990
Female: (10 * Bodyweight) + (6.25 * Height ) - (5 * Age) - 161
Katch-McArdle (Hybrid)
(370 * ( 1 - Bodyfat Percentage )) + (21.6 * (Bodyweight * (1 - Bodyfat Percentage))) + (6.17 * (Bodyweight * Bodyfat Percentage))
(McArdle, Katch and Katch, 2011) & (Sailrabbit.com, 2014)
The Katch-McArdle (Hybrid) is a variation on the original formula that can be found in the book released by McArdle, Katch and Katch (2011). The 'Hybrid' version was created by the author of this website, it provides more accurate estimates for leaner individuals as well as the average and overweight. I'd recommend checking out his site, its a very good resource for calculating energy expenditure and seeing the comparisons between the common formulas.
Cunningham
500 + ( 22 * ( Bodyweight * ( 1 - Bodyfat Percentage ) ) )
I dont have any source literature on the Cunningham formula as of yet, I am still searching for it. It is similar to the Katch-McArdle formula in which it only uses Bodyweight and Bodyfat Percentage to calculate energy requirements. There is a slight difference though, the Cunningham formula calculates RMR instead of BMR, so it does produce a marginally higher value. I will define the difference betwen RMR and BMR below to offer some clarity on what I just said.
BMR - Basal Metabolic Rate
This is a truer representation of your actual metabolic rate uninfluenced by digestion, exercise or just generally being awake for an amount of time. It is measured using gas analysis of calorimetry in a fasted state and immediately after waking from a prolonged sleep.
RMR - Resting Metabolic Rate
This is measured in the same way but without the conditions that are set with BMR, its slightly less accurate and will be higher than your BMR. But it could be more applicable to real world conditions.
Summary
Harris-Benedict (Revised)
Not really used anymore, outdated, only use for research purposes.
Mifflin St Jeor
The best formula for the average individual where body fat isnt too high or too low.
Katch-McArdle (Hybrid)
The most suitable formula where the individuals body fat is far from the average, to be used on people that are either very lean or obese.
Cunningham
Its quite popular within bodybuilding circles, should be used in a similar scenario to the Katch-McArdle but it will produce slighty higher estimates.
Protein Recommendations
I give two different protein recommendations in the calculator above, and there is good reason for this. The first protein recommendation is 1.2-2.2 g/kg of total bodyweight, this recommendation will only appear on the calculator when the user has programmed either a maintanence or a surplus of that maintanence. This coincides with a review paper by Helms, Aragon and Fitschen, (2014) where they stated that the collective agreement among reviewers is that a minimum protein intake of 1.2-2.2 g/kg is optimal to allow maximum muscle growth. A more recent study (Roberts et al., 2017) also showed during an isocaloric diet (a diet at maintanence calories) there was no significant difference in muscle recovery between a moderate intake of 1.8 g/kg of total bodyweight and high intake of 2.9g/kg of total bodyweight.
The second protein recommendation will pop up when you programme a deficit into the calculator. When you're in a calorie deficit, things get slightly different as muscle preservation or slight gains in muscle is the goal. This has been shown to require a higher level of protein. Helms et al., (2014) suggest that 2.3-3.1g/kg of Lean Body Mass (LBM) is a good range to start with, scaling up as the deficit gets more aggressive.