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Sunday
Oct312010

More than Just Calories In, Calories Out: The Caloric Balance Equation

If you’re one of the many people who have unsuccessfully tried to lose, maintain or even gain weight, developing a better understanding of metabolism may help you identify the causes of your lack of success. Since metabolism is complex topic, it requires a series of articles rather than just one big one. Today, we’ll take a look at what most people think of as the simple answer to metabolism – calories in and calories out. We’ll look at why it can be more complicated than simple math.

The Caloric Balance Equation

The caloric balance equation follows the theory that energy cannot be created or destroyed. That means if we add more energy to our body, something must be done with it. With diet and energy expenditure, energy can be measured in calories. In theory, if an individual burns 2500 calories in a given day, and consumes 2500 calories, he or she will maintain weight. The Center for Disease Control says “If you are gaining weight, you are eating more calories than your body is using. You will store these extra calories as fat and you’ll gain weight.”(1) Reading that sentence, it’s likely many people are left thinking “but I’ve cut back on calories before and I didn’t lose the weight I should have.” If our bodies were simple machines, this theory would work well. In fact, we can easily measure how many calories we burn at rest and during exercise, and make some assumptions about what we burn through daily activity. Theoretically, we can also measure how many calories we consume through food. However, our bodies are not simple machines, which is why there’s a lot more to the equation than just how many calories we eat and how many calories we burn.

The calorie balance equation states that the when the total calories we burn equal the total calories we eat, body weight is maintained. When it is tipped toward more calories burned we lose weight. When it is tipped toward more calories consumed, we gain weight. This theory simplifies our metabolism as being resting metabolic rate (the calories we burn when at total rest), the calories we burn from our daily activities and lifestyle (calories we burn doing what we do every day), the additional calories we burn from exercise, and the thermic effect of food (the calories burned in digestion). However, there is more to metabolism than a simple equation.

A Calorie is not a Calorie

When it comes to food, the caloric value on the label is not equal to the caloric value of the food once it’s in our body. In some ways, the foods we eat act like drugs. They can positively or negatively impact our metabolism depending on what they’re made of. Carbohydrates, protein and fat can affect certain hormones in our body. Carbohydrates, regardless of their type, are converted to sugar in our body and stimulate the release of insulin, a hormone that shuts down the ability to burn fat. That’s not to say they are bad, but the excessive amounts the average person eats can have an impact on the ability to manage weight. Evidence also suggests people can become addicted to certain foods based on how their brains respond to them. These foods typically high in processed carbohydrates and fat, stimulate the brain in a similar way to addictive drugs.(2) Knowing this, it’s no wonder people can feel helpless to the way some foods seem to control them.

Protein, carbohydrate and fat also require varying amounts of energy just to break them down. This is called the thremic effect of food. As an example, protein requires four to six times as much energy to break it down as fat and carbohydrate, which is why higher protein diets work so well for weight management. That means that the 100 calories worth of chicken breast is going to result in far fewer available calories than the 100 calories worth of pretzels someone could eat.

Getting Started: Keep it Simple

If weight management isn’t as simple as measuring calories in and out, is it even worth the effort to track it? Absolutely! One of the most eye-opening experiences you may have is getting your resting metabolic rate measured (also called a CaloriePoint Assessment). The reason it is so significant is that it provides a good benchmark to understand the number of calories you burn in a given day. You might be surprised to find it’s less than you think. Once you know what you burn, you can also log your intake in an online journal like myLT’s My Plan. You’ll easily see how close you’re getting to your suggested intake. Of course, there’s MUCH more to weight management than just the total calories, but it’s an interesting place to start. If you’re eating far more than you should, you’ll know you need to make some modifications. If you’re eating far less and you’re not losing weight, you may need to work with someone like a Registered Dietitian to understand why. As you’ll see in future articles, there are many reasons this could be.

Aside from understanding how much energy your body burns each day, the CaloriePoint can also show you whether you fall far below or above other people in your same age group with a similar build. Being well below normal levels can be an indication of hypothyroidism, adrenal fatigue, depression or other factors. Being well above normal may not be ideal either, as it can be a sign of stress or anxiety, hyperthyroidism, or other metabolic issues. Some issues can be discussed with a Registered Dietitian, but others may require the assistance of a medical doctor.

One final benefit of completing the CaloriePoint is to gain an understanding of the fuel your body burns at rest. While your resting metabolic rate is assessed, your respiratory quotient (RQ) is measured. Your RQ shows how much fat versus carbohydrate is burned at rest. The lower your respiratory quotient is, the more fat you burn at rest. It’s been shown that a lower RQ is associated with greater success losing weight.(3)

Summary

As we’ve discussed, for many of us, weight cannot be managed simply by measuring the calories we put in our mouth and the calories we burn. However, in order to identify if there is something else awry in your metabolism, you can start out with measuring these energy values. If you’ve been trying to lose weight for some time, and are eating less than your body requires, there are other answers. Before we get into those, we’ll take a closer look at what resting metabolic rate is all about, and how it can be affected by diet, lifestyle and our environment. That will be our topic for next weekend.

Written by Tom Nikkola - Director of Nutrition & Weight Management

References:

  1. CDC. Balancing Calories. CDC Healthy Weight online resource center. http://www.cdc.gov/healthyweight/calories/index.html
  2. Adam RC, Epel E. Stress, eating and the reward system. Physiol & Behav. 2007;91(4):449-458
  3. Barwell N, Malkova D. Leggate M, Gill J. Individual responsiveness to exercise-induced fat loss is associated with change in resting substrate utilization. Metabolism. 2009;58(9):1320-1328

This article is not intended for the treatment or prevention of disease, nor as a substitute for medical treatment, nor as an alternative to medical advice. Use of recommendations in this and other articles is at the choice and risk of the reader.

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