HOW TO FIGURE OUT HOW MUCH TO EAT... ACCURATELY
Well, if you couldn't tell I'm on a bit of a philosophy stint at the moment, however, my Practical Guide to Nutrition is launching soon so I figured I would throw some nutrition science back in the mix. I love science, but philosophy is a fun way to fill in the gaps of knowledge where science has yet to illuminate the answers.
Anyways, nutrition: People ask me about nutrition very frequently. They love to use the word "meal plan," "nutrition plan," "healthy foods," etc. There's always so much to unpack... But in all honesty, I would need 30-90 minutes of their undivided attention, a white board, some caffeine, and even then I'm not sure how effective I could be in getting them to understand nutrition and all that goes into having an effective eating pattern. Also, that's not what people want to hear. They want the elevator pitch diet that's going to transform their body. Not gonna happen. I'm gonna hit you with the honest, boring truth. And people don't care about that so I normally just smile and nod. I personally think it's the most exciting because it leads to real change and adaptation, but I think I'm among the few in that category.
I can put as much emphasis on it as I want, but you won't hear me talk about nutrition much because people don't actually want to prioritize it—at least not how it needs to be prioritized. I'm not quick to help with nutrition because it's arduous for the individual. I love all people, but I can spot discipline and genuine curiosity—I don't spot it often. Especially not when it comes to nutrition. It starts with YOU. YOU need to build a habit around your eating pattern, but I've already shared that (you can read about it here (and seriously that is the key)). The next step is understanding how to determine energy balance. Understanding how to calculate and manipulate energy balance is an art. It's something that when understood and applied will make you bullet proof in your nutrition. So how is this done? Grab a pen and piece of paper and follow along closely:
To calculate energy balance we will use a few gold standard equations (and yes we will need to do a little bit of math, but don't worry I hate math too, just remember spring break is right around the corner... always). The three equations we'll be looking at are:
- Mifflin St. Jeor
- Harris-Benedict
- Katch-McArdle
Mifflin-St Jeor Equation:
- For men: BMR = 10W + 6.25H - 5A + 5
- For women: BMR = 10W + 6.25H - 5A - 161
Revised Harris-Benedict Equation:
- For men: BMR = 13.397W + 4.799H - 5.677A + 88.362
- For women: BMR = 9.247W + 3.098H - 4.330A + 447.593
Katch-McArdle Formula:
BMR = 370 + 21.6(1 - F)W
where,
W is body weight in kg*
H is body height in cm*
A is age in years
F is body fat in percentage
The Mifflin St. Jeor has been shown to have the greatest amount of accuracy within a ~5% range, but we'll be using an average of our three calculations. Also, the Katch-McArdle calculation factors in lean body mass which plays an important role in our BMR. Now, as we move through this, please keep in mind that this will provide us with a rough estimate of how much energy we need to be taking in to maintain the basic processes that keep us alive. This is not by any means a precise measure, but an estimate is all we need. Counting calories down to the exact ones place value is silly given the comprehensive nature of calorie math especially once those calories get introduce to the body, when, and in what form (but I won't get started on that).
Let's do the math together quickly. We'll use George. George is a 24 year old male standing 6ft (182.88 cm) tall weighing in at 185 lbs (83kg):
*To get from ft to cm you need to multiply ft by 12 to get inches, then multiply by 2.54 to get cm
*To get from lbs to kg, you need to divide lbs by 2.205
*The numbers we put in are in orange so grab a piece of paper and plug yours in
BMR = 10(83.9kg) + 6.25(182.88cm) - 5(24yrs) + 5 = 1,864 kcal
BMR = 13.397(83.9kg) + 4.799(182.88cm) - 5.677(24yrs) + 88.362 = 1,954 kcal
BMR = 370 + 21.6(1 - 10) 83.9kg = 2,001 kcal
Avg: 1,940 kcal
I know this is just a bunch of numbers, let’s give this some context. With no activity, meaning to literally just lay in bed from morning to night, George would have to consume 1,940 kcal to reach energy balance (maintain his weight). This is our basal metabolic rate (BMR). If he gets up to pee, now it’s his resting metabolic rate (RMR). This is where things begin to get specific to our lifestyle. We're going to look at our total daily energy expenditure (TDEE) which factors in:
Basal Metabolic Rate (BMR) — 63% of TDEE
Thermic effect of food (TEF) — 10% of TDEE
Physical Activity Energy Expenditure (PAEE) — 27% of TDEE
Let's toss all of these figures in to figure out total calories and then breakdown macronutrients. We're first going to look at our "Katch-McArdle" multipliers (KMM) for activity level:
- Sedentary (little to no exercise + work a desk job) = 1.2
- Lightly Active (light exercise 1-3 days / week) = 1.375
- Moderately Active (moderate exercise 3-5 days / week) = 1.55
- Very Active (heavy exercise 6-7 days / week) = 1.725
- Extremely Active (very heavy exercise, hard labor job, training 2x / day) = 1.9
Now we have to do a little bit of math again:
BMR * KMM (Katch McArdle Multipliers) = TDEE
George is very active with heavy exercise four days/week and sports practice so we'll use 1.725 from the chart above:
1,940 * 1.725 = 3,346.50 kcal/day —> 3,347 kcal/day
This is taken from my book and leaves out a lot of the explanation behind the application of these equations/reasoning. I have a calculator that I built that's available on my site if you would like to check your work or just have it all done for you (here). Hopefully you're starting to see what goes into understanding nutrition, energy, the multifaceted nature of it, and how we can directly manipulate many of these variables through lifestyle.
That's it. Have fun, be safe, don't do anything I wouldn't do, and happy nutritioning.
~ Bonde
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