The Energy Balance Equation and Using it to Your Advantage When Losing Weight

Have you ever heard of the energy balance equation? It’s the key to shrinking that waist line, so you better know it. In my previous post The Truth about All Weight Loss Diets, I briefly talked about the energy balance equation and how all successful weight loss diets trick you to do one thing: eat fewer Calories (energy). Calories are simply the unit of measure for energy in food we eat. This is the energy balance equation:

Calories (Energy) in – Calories (Energy) out = Calories Lost or Gained by Body Stores (Energy Balance)

“Calories in” is the energy in food we eat and beverages we drink. “Calories out” is the energy that our body uses to maintain homeostasis, keep organs functioning, and contract muscles.   Our bodies store calories in the form of body fat, muscles, and liver and muscle glycogen (carbohydrates). When we eat more Calories than we use, our bodies store the energy (mostly as fat if you don’t exercise). When we eat fewer Calories than we use, our bodies break down body fat, muscle, and glycogen.  One pound of body fat contains about 3500 Calories. One pound of muscle contains about 600 Calories. Of course, the goal of weight loss is to lose mostly fat and to preserve as much muscle as possible, although some muscle will inevitably be lost except in some special circumstances. I will discuss ways to that you can make sure that you lose mostly body fat and minimize muscle loss while losing weight in a future article.

An Example:

Tom is a 250 lb man that needs 2500 Calories per day to maintain his weight. He is trying to lose weight so he eats 2000 Calories per day for a week

2000 Calories in – 2500 Calories out = -500 Calories Lost by Body stores x 7 days = 3500 Calories Lost

Ok so how much weight did Tom lose? It depends on how much of that weight loss is muscle and how much is fat.

Scenario 1: Tom did a good job minimizing muscle loss and lost 90% of his weight from fat and 10% from muscle. He lost .98 lbs of fat, .11 lbs of muscle, and 1.09 lbs total.

Scenario 2: Tom did not follow these guidelines. He lost 70% of his weight from fat and 30% from muscle he would lose .93 lbs of fat, .4 lbs of muscle, and 1.33 lbs total (not counting water weight changes).

As you can see, Tom lost less fat in scenario 2 and lost almost four times as much muscle!  If you follow my guidelines, a 500 Calories deficit will cause a weight loss of about 1.09 lbs per week, mostly from fat. If not, you will lose more weight, but less fat and more muscle.

How Big of a Calorie Deficit Should I Have?

For simplification purposes, think of a 500 Calorie deficit per week causing about 1-1.5 lbs of weight loss per week and a 1000 Calorie deficit per week causing about 2-3 lbs of weight loss per week depending on the ratio of fat to muscle lost. Most people should try to create a Calorie deficit of 250-1000 Calories per day to lose .5-3 lbs per week (depending on a number of factors). Heavier people may safely lose weight faster (2-3 lbs/week as a general statement) and leaner people should try to lose weight slower (.5-1.5 lb/week).

*Note: Some people say that a 500 Calorie deficit will cause 1 lb of weight loss per week, but they are assuming that 100% of the weight lost is fat which rarely happens.

Let’s take a more in depth look at each section of the energy balance equation. If you know how it works, you can use it to your advantage.

Calories In

As mentioned previously, Calories in are the Calories that come from food and drink. For our food to “count” towards calories in, it must be absorbed by our body. There are some ways that you can prevent Calories from being absorbed by your body. If you eat more soluble fiber (found in fruits, vegetables, whole grains like oatmeal), then you will poop out additional calories. You also only absorb about 1.5-2.5 Calories per gram of fiber compared to 4 Calories per gram of carbohydrates too. So the effect of fiber is twofold in decreasing Calories you absorb (and has many other benefits for weight loss and health too!). Resistance starch is another food that resists absorption and you don’t end up absorbing as many Calories. Look for pastas and other grains made with resistance starch when you eat these foods. Artificial sweeteners are also a great way to avoid absorbing calories. Substitute these in recipes. Splenda can often be substituted in a 1:1 ratio with sugar and if you don’t like the taste, try replacing ¼- ½ of the sugar with splenda to see if you can mask the taste while reducing Calories. Certain supplements may prevent absorption of calories, but I want to focus the things that make the biggest difference and these supplements have minimal effect – remember to focus on what matters.

Calories Out

Calories out refer to the calories needed to maintain homeostasis in your body, move your body during exercise and every day activity (including keeping your posture, standing up, twitching, ect.), and the energy lost as heat when the body absorbs food. I discuss specific types of exercise in a future article and give you some general guidelines. Exercise is an important component of weight loss by increasing energy burned and for maintaining muscle. Other ways to increase your activity and calories used every day is to find simple ways to keep yourself moving during the day. Try parking farther away so you walk a little further, take the stairs, tap your foot when you sit down, get up from your desk at work and walk a lap… you get the idea. Little things matter in the long term. Another way to increase your energy out is to eat more protein (which has additional benefits for weight loss as well). Although food labels say that protein has 4 Calories/g, the body loses energy as heat while absorbing it makes it actually count as 3.2 Calories/g. If you were to replace 50 g of carbohydrates every day with 50 g of protein, you would lose an extra 40 Calories every day (and likely feel fuller and prevent muscle loss).

Many people may be interested in the effect of drinking water or cold water on weight loss. The studies have shown inconsistent results, but drinking plenty of water should be a part of any weight loss diet to keep you full and for overall health. Having some extra fluid is likely dangerous as long as you aren’t ridiculous. To get an idea of how much fluid you need every day, use this formula to get a minimum or use my fluid needs calculator:

(Weight in lbs x .275 cups/lb) + 1 cup for every 1/2 lb of weight lost during exercise = Needs

Calories, Protein, and Fluid Needs Spreadsheet

*If you have heart failure, CKD, or another condition that causes fluid retention then DON’T use this formula.

A Random Note

Many people think of weight loss mostly as increasing exercise. Unfortunately this is not true. For most people, diet is likely the biggest factor that is holding you back from your weight loss goals. Exercise is great for so many reasons, especially during weight loss, but those of you that consider exercise to be your main problem holding you from losing weight should really give their diet a close examination. Again: eating fewer Calories will likely make a bigger impact than exercise on your weight loss (unless you are an athlete).

If you believe the energy balance equation is false or want an even more in depth explanation then you can read this great article by Lyle McDonald-

Courtesy of Romano Carratieri

What Matters in This Blog Post

1. Calories (Energy) in – Calories (Energy) out = Calories Lost or Gained by Body Stores (Energy Balance)

2. One pound of body fat contains about 3500 Calories. One pound of muscle contains about 600 Calories. You lose both muscle and fat when you lose weight.

3. A 500 Calories deficit causes 1-1.5 lbs and a 1000 Calorie deficit causes 2-3 lbs of weight loss per week depending on the amount muscle loss. If you follow the guidelines here “sadfadf link”, you will lose less muscle.

4. Looking to lose weight? Eat 250-1000 Calories less than you need every day.

5. Fiber, resistant starch, and artificial sweeteners are a great ways to reduce Calories in by decreased absorption.

6. Increasing exercise, finding ways to increase movement throughout the day when not exercising, and eating more protein are the ways to increase your Calories out.

7. Eating fewer Calories will likely make a bigger impact than exercise on your weight loss (unless you are an athlete).


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