Calculate Your Energy Balance Equation

If you're trying to lose weight, it is helpful to understand energy balance. Most people don’t think of their weight loss journey as a math problem. But in many ways, it is. To lose weight, you need to calculate your energy balance equation, then change the numbers to achieve weight loss. If you can get your numbers to tilt in the right direction, you’ll lose weight more effectively.

Energy Balance Equation

Energy balance is simply the relationship between your energy input and your energy output. The complete energy equation looks like this:

It doesn't look very complicated. However it can be difficult to know your energy expenditure throughout the day. Counting your energy intake is a matter of reading Nutrition Facts labels, when available, or estimating caloric density. So to figure out your energy balance you need to gather some important information.

Calculate Energy Balance

To learn how to manage your energy balance, you need to gather numbers related to your energy input and energy output.

Energy Input

We input energy when we eat. The food we consume provides calories. Calories are simply a unit of energy or heat. The food we eat and the drinks we consume provide different amounts of energy. Protein and carbohydrates each provide 4 calories per gram, and fat provides 9 calories per gram.

So how do you know your energy input number? Count the number of calories you eat each day. You can do it with a simple downloadable food diary or you can use a popular calorie counting app. An average woman may consume anywhere from 1,600 to 2,400 calories per day. That's a pretty big range. To get the most accurate number for you, track your calories for at least a week.

Energy Output

Energy output happens when your body uses energy. We often refer to this as "burning" calories. Even when you’re sleeping, your body uses energy to perform basic functions like breathing and circulating blood. The rate at which your body burns calories at rest is called your basal metabolic rate (BMR). BMR makes up roughly 60% to 75% of the total number of calories you burn each day.

You also expend energy during activities of daily living, like washing dishes or shopping, and of course, through physical exercise. These activities make up about 15% to 30% of your total calorie burn each day. The last 5% to 10% of calories (give or take) are burned through the thermic effect of food when you eat and digest meals and snacks.

There are different ways to calculate the number of calories you burn each day. One of the simplest ways is to use a calorie calculator.

Energy Balance and Weight

To determine how your energy balance will affect your weight, you need to determine if you have a positive or negative balance. To do so, take your numbers and input them into the equation at the top of the article. Then find out if you have a negative energy balance or a positive energy balance.

Positive Energy Balance

A positive energy balance occurs when your energy input is greater than your energy output. That is, you eat more calories than your body uses. Your body stores excess energy or calories as fat. This results in weight gain.

Negative Energy Balance

Weight loss occurs when you create a negative energy balance. That is, you burn more calories than you consume. When this imbalance occurs, your body burns stored energy (fat) in order to function and you lose weight. A negative energy balance is sometimes called a calorie deficit.

When you evaluate your own energy balance, it's best to get the numbers as accurate as possible. Even small differences in energy input and energy output can make a big difference in your weight.

Energy Balance Equation Examples

Are you ready to calculate your own energy balance? Here are two sample equations to use as a guide.

Example #1: Megan

• Calories consumed each day: 2,000
• Calories burned each day: 1,750
• 2,000 (energy input) – 1,750 (energy output) = 250 calories

Megan has a positive energy balance of 250 calories per day. That doesn't sound like much. But over the course of a week, her estimated balance would be 1,750 calories or about enough to gain a half pound of weight.

Example #2: Cameron

• Calories consumed each day: 1,800
• Calories burned each day: 2,050
• 1,800 (energy input) – 2,050 (energy output) = -250 calories

Cameron has a negative energy balance of 250 calories. Over the course of a week, her body will need to burn 1,750 calories of stored fat to meet its needs, and she could lose approximately one-half pound of weight.

A Word From Verywell

So if weight loss is just a simple equation, then why is it so difficult to lose weight? Because there are many factors that affect both your energy input and your energy output. Things like your medical status, age, and mood affect your energy balance equation every day. Weight loss is a simple equation, but finding the right balance requires a little bit more work.

If you are at the beginning of your weight loss journey, or if you are questioning your current diet and exercise plan, the energy balance equation is a great place to start. You don't need to buy fancy tools or invest in an expensive weight loss program.

Try to make some changes on your own. Evaluate the factors that affect your caloric intake and caloric output. You have control over some factors (like activity level) and no control over others (like your age and sex). Simply change what you can to tilt the scales of your energy balance equation and reach your weight loss goals.