Nutrition 101 - Part 1 Introduction, Metabolic Rate, & Determining Your Daily Energy Expenditure

By: Steve Troutman, Sep 25 2011

Introduction

Food.  Put it in your mouth, chew it up, and swallow.   Let your body’s biochemistry do its magic by breaking it down and deriving usable energy from it.  Move around expending said energy.  Rinse.  Repeat.
Rewind a couple of million years ago and this process worked.  Our species ate to survive.  They moved to hunt and gather.  They instinctively balanced calories coming in from eating and calories going out through activity.  When they didn’t – when calories in were greater than calories out -  it was likely followed by the opposite.
They’d eat lots in anticipation of times of food scarcity. In other words, they’d fatten up so they’d be warm and have stored energy through the winter months when animals darted towards the Equator and plants died off.  This way of life existed for expanses of time that are beyond  your comprehension.

On a biogenetic level, our species is a product of its surroundings.  In other words, our environments influence the very systems that comprise and regulate our bodies.

For longer than not, the human species struggled to survive and food scarcity was very real.  In turn, our bodies have evolved to be very good at conservation.  What we’re left with is a body that loves to store fat and is hesitant to pack on slabs of muscle.  It’s quick to resist weight loss and hesitant to resist weight gain.
Looks pretty crappy through the eyes of modern man (and woman!).  This complex system is also one of the key reasons why our species is alive today though.

For an in depth explanation of these systems, I can’t recommend the work of Lyle McDonald enough.  He has an enormous collection of free articles on his website and his books are some of the best I’ve read in the field.  He has influenced my nutrition philosophies more than anyone.

More recently, the environments around us have changed drastically. Ten thousand years ago, our society began transitioning from the hunter-gatherer mode of subsistence to agriculture and the domestication of animals.  In terms of our obesity epidemic, this was a critical shift.  Food availability was becoming more stable and abundant.  Mobile societies that once moved with the food were becoming stationary.

Between then and now, technological advancement has skyrocketed relative to where we were a mere 100 years ago.  Computers, televisions, video games, fast food, the Internet – so many things have changed around us.  The evolution of our bodies certainly hasn’t kept pace with the evolution of technology.  In a world that’s now dominated by sedentary pursuits, the human body’s still built for survival during times of famine.

Archeological and anthropological studies have traced obesity back as far as 25,000 years ago.  You can find an interesting review of the history of obesity written by renowned obesity researcher, George Bray, here.   Of course the prevalence of obesity wasn’t nearly what it is today.  It wasn’t until the 70′s and 80′s that the rates of obesity and extreme obesity really took off.

Courtesy of www.cdc.gov

In the culture of today, it’s commonplace to see someone sporting 150 pounds of excess body fat.  Think about that for a second.  There are 3,500 calories in 1 pound of fat.  These folks are toting around 525,000 calories worth of excess fat.  Considering an obese man might expend in the neighborhood of 4,000 – 5,000 calories per day and he could easily shovel down 1,500 + calories in a single meal* –  that 525,000 calories is a lot of energy that’s likely to remain stored away if there’s no dietary and exercise intervention.

*The McDonald’s nutrition fact sheet can be found here.  A double quarter pounder with cheese (740 cals), large fry (500 cals), and a large Coca-Cola (330 cals) totals nearly 1,600 calories.

Intervention requires education and that’s what this page is about.  The information we’re going to cover isn’t solely for obese folks with 100+ lbs to lose.  It’s for anyone who wants to have a better handle of how nutrition influences his/her body and health.  Those interested in performance enhancement, obesity prevention, and body composition changes will all find useful information below.

The last thing you’ll catch me doing is prescribing diets to people.  “Eat this, not that.”  If you’re looking for a specific diet, you’ve come to the wrong place.  That’s not me.  My intent is to educate you on the basics that drive long term success.  These basics are constant across populations… meaning they pretty much apply in varying degrees to everyone.

I know reading isn’t the “in” thing nowadays.  Most people are either seeking validation for their current strategy or they’re looking for groundbreaking top secret information that will expedite the process of getting in shape.  They want to be spoon fed.  And there’s no shortage of con men who are willing to do it.
I could easily cater to these folks too.  All I’d need to do is whip up a gimmicky looking website with miles of ad copy that’s loaded with altered before & after pictures, ‘scientific’ sounding information, and promises of life-altering transformations in a matter of a couple of months.
Or…
I could take the high road and hope there are still some people out there who are looking for sound, evidence-based advice who want:

• To be in command of their progress
• To be an informed consumer
• To be guided by reason, objectivity, and evidence rather than emotions and lies

I might not catch as many flies with this trap, but at least the flies I do catch will be smart enough to free themselves and advance.

 The information below represents the backbone of all diets.  Let’s assume you know absolutely nothing about nutrition… this way we’re on a level playing field. 

Metabolic Rate

Life requires energy.  There’s an energy cost to breathing, digesting, thinking, dancing, cleaning, exercising and everything else that we do.  The total amount of energy our bodies burn in a day can be referred to as daily energy expenditure (DEE).

This cost is paid for with energy derived from food.  What we eat and drink gets broken down into useable forms of energy that fuels our daily energy expenditure.
The daily energy expenditure can be divided up between basal metabolic rate (BMR), thermic effect of activity (TEA), and thermic effect of feeding (TEF).

DEE = BMR + TEA + TEF.

Basal Metabolic Rate is the energy our bodies expend at complete rest.  Unless by rest you mean dead… your body expends a relatively large amount of energy maintaining itself while at complete rest.  Organ function, cellular processes, tissue maintenance, and a number of other factors comprise BMR.  While it varies, BMR accounts for 50-70% of our daily energy expenditures.  Any variance that does exist can typically be attributed to differences in lean body mass, age, gender, body composition, and genetics.
The Thermic Effect of Activity is the energy we expend moving around.  This can be structured exercise or it can be what’s referred to as spontaneous physical activity (SPA) or non-exercise activity thermogenesis (NEAT).  The latter accounts for the energy expended gardening, walking up a flight of stairs, fidgeting, typing, cleaning, having sex and all other forms of movement.  Obviously an Olympic athlete who’s training for a living is going to have a much higher TEA than the traditional computer jockey of modern society.  TEA accounts for 20-50% of the average person’s metabolic rate.

Lastly, the Thermic Effect of Feeding is the energy expended digesting and utilizing the foods that we eat.  Different macronutrients require varying amounts of energy to digest – protein being higher than carbohydrates and carbohydrates being higher than fats.  The research isn’t great in this area, but it’s not all that important seeing as how TEF accounts for 5-10% of metabolic rate.

By knowing how many calories your body is expending each day, you can tailor the amount of calories you consume on a daily basis in order to gain, lose, or maintain weight.  If there’s more energy going in the door than out, weight will be gained.  Vice versa, when there’s more energy going out the door than coming in, weight will be lost.  Of course weight maintenance is achieved when energy in and energy out are balanced.
Rest assured that I know there’s more to reaching one’s physique, health, and/or performance goals than controlling calories in and calories out.  Keep reading to find out why. (parts 2-5 are coming very soon)