Why Calories In vs Calories Out Doesn’t Work


For most of us the easiest part about losing weight is if we chop off a leg.  For the rest of us it's struggle and for good reasons.  Your typical advice of move more and eat less is still quite valid, but when you're trying to calculate this out through the basic formula of overall calorie intake in minus calories out it isn't what it seems.  There's a whole lot more complexity to the body than we care to think about.

Here's just some of the reasons why the calories in minus calories out equation doesn't work correctly.

How Many Calories Are In A Pound of Fat?

Let's put it in perspective. A pound of fat is about 3500 calories.  That's a lot of calories to burn off.

To burn off a pound of fat jogging (at 150lbs) you'd have to run for about 6 hours at a 8km/hr pace.

Now if you're walking at a relatively slow pace of 3km/hr you'd have to walk for a little over 24 hours to burn that amount of calories.

If you're circuit training with weights you'll burn about 574 calories per hour (if you're lifting pretty intensely with minimal rest) which is about 6 hours worth of training per week.

Or for fun, let's say you're going to do burpees to burn off your 1lb of fat.  It's going to take about 350 burpees to burn of one pound of fat.  Give or take a few for sake of bodyweight.

So let's just say it's a lot of activity to burn off one pound of fat!  Sucks right.  There's no way to burn off this many calories all at once.  Which is why the fast approach to burn off bodyfat just doesn't work.  You simply can't workout hard enough and for long enough.  Your body will fall apart.  That's why it has to be done in stages.

And this leads us to our next problem...

You Never Lose 100% Of Just Fat

The overall equation of calories in/calories out was based on JUST fat.  You have more biologically active tissue that can fluctuate your weight than simply body fat.  And you'll never lose just fat in any diet or exercise program.  Your body is constantly fluctuating in weight from changes in water, sodium, food you've eaten and expelled, protein (as in muscle tissue gains or losses) and hormones (that's a big one for the ladies out there).

You can't expect to just simply eat 500 calories less each day and drop off a pound of pure fat over the course of the week.

Often times you're burning off muscle tissue as well as fat, which has about 600-700 calories per pound.

This is very common with people that follow a crash pattern of dieting where the calories are too low to sustain body function.  We're talking below 1000 calorie a day diets!  Now for a while this approach will work, but your body is pretty smart.  It knows when you're not giving it enough fuel to use.  It's going to scrounge around for whatever spare calories that it can by putting the body into a catabolic state (breakdown) and start tearing apart tissues in order to use for fuel to keep on running.

It's basic survival mechanism is to survive.  It doesn't care that you have 10-20 pounds of fat you want to get rid of, it simply knows you're not feeding it enough to get the job done.  So the body starts breaking down things it doesn't need.

Now some of that tissue will be bodyfat of course.  But you also have to consider stored glycogen (stored sugars in the muscle).  Typically the body will turn to these first.  In addition, if that muscle tissue you have isn't being readily used for picking up heavy things and weight lifting the body doesn't want to hold onto it.  Muscle tissue is actually one of the first things the body starts degrading when you crash diet, simply because it's an active tissue.  It burns and consumes a lot more calories just at rest, so the bodies best option when not getting enough food is to get rid of it.

This is why exercise is an important part of the process when you're trying to lose weight.  If you're not using that tissue you're not teaching your body to hold onto that muscle mass.  Then you lose it and it's much harder to add muscle back on after it's gone.  So do yourself a favor and lift some weights to help hold onto that muscle mass.


Quick Weight Loss is Primarily Muscle and Water

Now diet centers or fad diets will want you to switch food types to generally a more fat and protein based diet, like the keto craze right now and stave off from exercising.  Why?

Because, if you change your diet and avoid carbs like the plague you're going to get a massive amount of water weight loss in the first week.  Probably about 5-10 pounds of weight loss.  Awesome, that's motivating for sure!

In addition to that, not exercising will promote muscle wasting (as stated above, exercise helps hold onto muscle tissue).  Think about it this way, if a pound of muscle is only 600-700 calories and you're dropping your calories down to say 1000 calories when you need 2000 calories to maintain your weight, that's about 9 to 12 pounds of weight you can lose in a week.  It looks good on the scale, but is that really effecting your fat stores?

The answer is NO.  Ultimately you've just dropped body water and some muscle mass to make the scale number go down, while the body is still maintaining a high amount of fat.  Even if the equation is about 50% fat loss and 50% muscle loss you're still fighting a losing battle, because as you lose more muscle you start losing your "engine" or your ability to burn more calories faster the more muscle mass you lose.

This leaves you in a state of being "skinny fat" where you have little muscle mass, no power, no strength, and a bunch of lose saggy skin that is loaded with fat and not much else.

So drop the carbs and don't exercise at all and you're going to lose weight for sure.   But what is that weight you're losing?

So How Do We Lose The Fat?

The answer is simple, but harder to do as with most simple things.

Be consistent in eating better over time.  You're basically going to need to stay in a caloric deficit for a long period of time, while engaging in exercise to keep yourself on track.

Calculate Your Starting Point

Start with calculating your overall metabolic rate or tracking your calories throughout the week (an estimation is about 10kcals / 1lb of bodyweight).

You're going to want to take that total calories consumed over the week and get an average of your calories your already consuming.  Make sure you're honest and measuring your food with a food scale or cup measurements.  The more accurate you are the easier this will be.  Most people will be off by about 10-25% of overall calorie consumption (which is horrible, but hey it's a starting point).

From their we need to see a goal that's about 250-500 calories lower than what we're already consuming.  This is where we start out.  Be consistent and keep things under that 250-500 calorie range for a two week period.

Track Your Progress Every Two Weeks

Then record weight and body composition.  Very important to keep track of the body composition because that will tell you what's really going on versus the scale tends to fluctuate depending on a variety of things.

Read this posting on the fluctuations on the scale and Weighing In On A Woman's Scale Obsession.

Add In Exercise

Increase your daily activity.  Walk more, take the stairs, stand up and move at work, etc.  This actually adds up to a lot of extra calories burned throughout the day that you're really not considering and it's less grueling than physical exercise.  However we need both to help us out in the end.  Especially if there's a lot of weight to lose.

Focus your other main exercise efforts on hard physical exercise like weight lifting and hard cardio at least three times a week and then build that up where you can.  Remember, hard is relative and depends on where you start out.  Once you've adapted to the tough stuff and it becomes easy it's time to up the ante a bit more so you can continue burning off more and more calories per unit of time.

Be Consistent for a Long, Long Time

If you can consistently eat a little less and workout a little more you'll eventually get to the point where you can burn off all the fat.   But it's going to take time!  It didn't take a week to get out of shape and it'll definitely take longer than a week and a couple jumping jacks to get back in shape.  So dig in for the long haul!

Consistency and long term caloric deficit is what works for everyone.

Last Key Point

Don't get flustered along the way.  If you stall out, stop, take a knee, breathe, look around and analyze what's going on and make adjustments from there.  There's always a way out.  You just sometimes have to find out why what you're doing isn't working.

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Jess Howland

Jesse "Captain Smash" Howland is the owner of SMASH’s Strength Lab, which offers targeted personal training to reach a variety of fitness and physique goals. A natural bodybuilder, competitive powerlifter, certified personal trainer, and nutrition coach, Jesse is often the go-to resource for personal training Ottawa. He studied Exercise Science at Oregon State University and even trained at the world famous Gold's Gym. He's a former US Army Captain with the 86th Infantry Brigade Combat Team, a former blog writer at Veterans Fitness Career College, and former Chief Executive Officer at U.S. Army Forces Command (FORSCOM). His workouts and personal training are army-inspired to help reach your weightloss, athletic, or physique goals.