Calories In vs. Calories Out for Weight Loss

The equation for weight loss is this: Burn more calories than you ingest and you will lose weight.

Let's talk about calories.  There are some basic ideas and fundamental rules every first responder needs to understand when it comes to nutrition and calories.  

Every single diet that has ever been shown to lead to weight loss has done so because it leads people to eat fewer calories than they burn.   Common diets like keto, vegetarian diets, low-carb/high-fat, paleo, intermittent fasting, or Atkins – all create a situation where you eat fewer calories, reach a caloric deficit, and lose weight.  

If you are wondering if you could eat burgers, fries, and ice cream and lose weight?  As long as you are in a caloric deficit, yes you can (click here for more proof).  You will probably feel like crap and eventually, your overall health will deteriorate, so I do not recommend it. 

There are other reasons why just eating "crap" foods will not work over the long term.  For one, your diet needs to satisfy your hunger cravings.  Eating high-fat and sugar foods will eventually lead to more cravings that will have you eating too many calories and gaining weight.  Another reason is that you need to eat good sources of protein to maintain muscle mass.  A diet based on burgers, french fries, and ice cream will not give optimal protein levels.  And, poor nutrition will likely not give you ample vitamins and nutrients needed for long-term health and metabolism.

When it comes to weight loss, it doesn’t matter how many “healthy” foods you have in your diet: if you are eating too many calories, you will not lose weight. 

Eating too many calories simply means that your body has taken up more energy than it has used. It’s physics and physiology. Eating more calories than your body uses is called being in a caloric surplus and leads to weight gain.  Eating fewer calories than your body uses is called being in a caloric deficit and leads to weight loss.Is it really that simple?  I have often heard many people state that it is not as simple as calories in vs. calories out (CICO) because the body is more complicated than that.    

firefighters need to understand calories...

The Calories In vs. Calories Out (CICO) Challenge

The one thing we all need to understand is that figuring out the calorie requirements (calories burned) can be difficult because they change over time.  We use different amounts of energy from day to day, and as body composition and weight change so does your metabolism.  

We also need to note that stress, illness, and hormones can play a role in the number of calories we burn (calories out).  And, adding to that is how difficult it can be to estimate how many calories we are actually consuming each day. 

The purpose of this post is to show that the calories in versus calories out concept does work for weight loss.  Sometimes the fact is obvious and sometimes it is not and there are certain situations that may not believe it but the answers are there if you keep your mind open and examine every factor.

So, to help, here are four common calories in/ calories out (CICO) scenarios that address common misconceptions.  In each case, it might be tempting to assume that CICO doesn’t apply. But look a little deeper, and you’ll see the principles are always present.

calories can climb if you do not watch them.

Scenario #1: “I’m only eating 1,000 calories a day and I’m still not losing weight!”


I have worked with thousands of clients over my 30 years in the fitness industry and have heard this stated just as many times in the firehouse.  The conclusion we like to jump to in this scenario is that our metabolism is broken and the calories in/ calories out formula does not work for us.

Now, there could be a hormonal or stress issue that can result in a smaller number of calories burned.  However, when someone’s eating 1,000 calories a day but not losing weight, it’s usually due to one of these two reasons.

Reason #1: We often underestimate calorie intake.

It’s easy to miscalculate how much you’re eating, as it’s usually unintentional. The most typical ways we under-calculate caloric intake are:

  • We don’t record everything at the moment and forget to log it later on.
  • We  “forget” to count foods selectively due to small portions or “wishes” that we had not eaten them. 
  • We underestimate portions.  For example, without precisely measuring “one tablespoon of peanut butter,” it might actually be two, adding 90 calories each time you do it.  This is very common in the firehouse, the large platters can distort serving sizes.  
  • And, sometimes we do not track bites, licks, and tastes of calorie-dense foods. That small bite of brownie at the firehouse could easily add 100-200 extra calories.

Calories can add up quickly.  A landmark study, and repeated follow-up studies, found people often underestimate how much they eat over the course of a day, sometimes by more than 1,000 calories.   This of course can really add up to extra pounds. 

I only ate chicken for lunch

Reason #2: We overeat on the weekends or at the firehouse.

Shifts can be stressful, and those occasional strolls through the kitchen taking bites of brownies and/or cookies can really add up.  And sometimes on weekends and off days, we like to put our guard down and let loose.

Here’s how it goes: Let’s say you are eating 1,500 calories a day on weekdays, which would give you a 500-calorie deficit.  But on shift and on the weekends, you deviate from the plan just a little.

  • You attend a department social event and have a drink (or two)and a few slices of late-night pizza.
  • An extra big lunch after a workout.
  • Extra desserts at the firehouse.
  • Brunch on Sunday.
  • Taco Tuesday at the Firehouse.

The final tally: An extra 4,000 calories can be consumed on days off, and/or an extra 500-1000 calories on each shift.  This then effectively cancels out any deficit, bumping your average daily calories to over 2,000 calories instead of 1500.  Which, can then lead to some weight gain.    

My point is this.  If you feel like you are slashing your calories dramatically, but you aren’t seeing the expected results, look for the small slip-ups and measure them.   Start logging food and be mindful of your serving sizes.

Scenario #2- “I’ve been eating the same way forever, but suddenly I started gaining weight.”


 What happened? More than likely, “energy in” or “energy out” did change, but in a way that felt out of control or unnoticeable.  The culprit could be:

  • Slight increases in food intake, due to changes in mood, hunger, or stress.
  • Physiological changes that resulted in fewer calories burned during exercise and at rest.
  • The onset of chronic pain, a new job, or seasonal change provided a dramatic decrease in non-exercise activity thermogenesis (NEAT).
  • Significant changes to sleep quality and/or quantity, impacting metabolic output and/or food consumed.

In all of these cases, CICO is still valid. Energy balance just shifted in subtle ways due to lifestyle and/or health status changes.  And because the changes were so subtle they were hard to recognize until the scale moved in the wrong direction.

Scenario #3: “My hormones are wreaking havoc on my metabolism, and I can’t stop gaining weight.”


Hormones seem like a logical scapegoat for weight changes.  And while they’re probably not to blame as often as people think, hormones are intricately entwined with energy balance.

But even so, they don’t operate independently of energy balance.  In other words, people don’t gain weight because of “hormones.”  They gain weight because their hormones are impacting their energy balance.  This often happens during menopause or when thyroid hormone levels decline.  But this doesn’t negate CICO: Your hormones are simply influencing “energy out.”


Dilemma #4: “I’m eating as much as I want and still losing weight.”


This might be the top reason some people reject CICO.  Say someone switches from a diet of mostly processed foods to one made up of mostly whole, plant-based foods. They might find they can eat as much food as they want, yet the pounds still melt away.  People often believe this is due to the “power of plants.”  Yes, plants are great, but this doesn’t disprove energy balance.  Because plant foods have a very low energy density, you can eat a lot of them and still be in a calorie deficit. Especially if your previous intake was filled with lots of processed, chemical-laden foods.

It feels like you’re eating much more food than ever before—and, in fact, you really might be.  On top of that, you might also feel more satiated because of the volume, fiber, and water content of the plants.  All of this is great, but it doesn’t negate CICO. You are still eating fewer calories, just more food. 

Take the ketogenic diet, for example.  In this case, instead of eating plant foods and still losing weight, they’re eating meat, cheese, and eggs. Those aren’t low-calorie foods, and they don’t have much fiber, either.  As a result, plenty of low-carb advocates claim keto offers a “metabolic advantage” over other diets.

Here’s what’s most likely happening:

  • Greater intake of protein increases satiety and reduces appetite.
  • Limited food choices have cut out hundreds of highly-processed calories they might have eaten otherwise (Pasta! Chips! Cookies!).
  • Reduced food options can also lead to “sensory-specific satiety.” Meaning, when you eat the same foods all the time, they may become less appealing, so you’re not driven to eat as much.
  • Liquid calories—soda, juice, even milk—are generally off-limits, so a greater proportion of calories are consumed from solid foods, which are more filling.
  • Higher blood levels of ketones—which rise when carbs are restricted—seem to suppress appetite.

For these reasons, people tend to eat fewer calories and feel less hungry on the ketogenic diet.  Although it might seem magical, the keto diet results in weight loss by regulating “energy in” through a variety of ways.


You might ask: If plant-based and keto diets work so well, why should anyone care if it’s because of CICO, or for some other reason?

Well, depending on the person—food preferences, lifestyle, activity level, and so on—many diets, including plant-based and keto, aren’t sustainable for the long term. 

Watch out with liquid drinks. The calories can add up.

In all honesty, long-term results aren’t diet dependent. They’re behavior dependent.

Maintaining a healthy body (including healthy body weight) is about developing consistent, sustainable daily habits that help you positively impact “energy in” and “energy out.”

Here are the best ways to control the calories in versus calories out equation and accomplish your goal weight.  

  • Only eat until you are 80% full.  Click here to discover what 80% full is. 
  • Eat slowly and mindfully.  Try to avoid distractions when eating and slow down.
  • Eat minimally processed foods.  The more natural the food, the better.
  • Get more high-quality sleep.  A lack of sleep can cause bad cravings.
  • Take steps to reduce stress and build resilience.
  • Move more throughout the day.  By moving more, you are burning more calories and expediting more energy.
  • Start to monitor and measure what you are currently eating.  Read labels and understand what serving sizes should look like.
  • Stay hydrated!  Try to drink at least 70-80 ounces of water each day.  This will help with digestion and help you feel more full throughout the day.
Best ways for first responders to control calories.

It’s about viewing CICO from 10,000 feet and figuring out what approach feels sane—and achievable—for you.  Do not get too bent out of shape (yet) about what you are eating,  add the steps above and start to take control of your nutrition.  

Stay safe and take steps to get Better Every Day.






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Helen Kollias, PhD, John Berardi, PhD, CSCS.  The surprising problem with calorie counting.

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One final point about calories...

Just because it's there doesn't mean you have to eat it...v2

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