What Is Calories In vs. Calories Out?

Use the Calorie Equation to Get Weight Loss Results

calories in vs calories out

Tetra Images / Getty Images

If you are considering losing some weight or have been told you would benefit from weight loss for medical reasons, then it might be helpful to understand the concept of calories in versus calories out. This equation can help you to understand the basic metabolic process of weight loss.

Calories In vs. Calories Out

The calorie in vs. calorie out equation is based on your food intake and your daily metabolic needs. The food you consume supplies calories. Those calories are used to support your daily metabolic needs, including the energy needed for basic physiological functions and for physical activity.

If you consume more food than you need (calories in), the excess calories turn into extra weight. But if you burn more calories than you consume (calories out), you burn stored body fat for energy and you lose weight.

Basal Metabolic Rate

Everyone has a basal metabolic rate (BMR). Your BMR is the number of calories your body needs for basic, life-sustaining functions such as circulation, breathing, and nutrient processing. This number is determined using a calculation that takes certain factors into consideration including a person's age, height, weight, and activity level. You can calculate your basal metabolic rate using a mathematical formula.

Physical Activity

The number of calories you need to sustain your current body weight is equal to your BMR plus calories needed for your current level of physical activity (PA). Your physical activity includes any exercise that you participate in and all non-exercise physical activities (such as folding laundry, walking to your coworker's cubicle, cooking, or mowing the lawn). The number of calories you burn through physical activity varies substantially from individual to individual.

Calorie Deficit

If you want to lose weight you must create a calorie deficit by either consuming fewer calories than your body needs, burning extra calories through physical activity, or some combination of the two. For example: if a person needed 2500 calories per day to maintain their body weight and they reduced their calorie intake by 500 calories per day, they would be expected to lose about one pound of body weight per week.

Think of food as fuel and your body as a car. Food is the energy our bodies need to move. Overeating is like over-fueling. Any excess fuel you don't use turns into fat and weight gain begins.

Other Factors

The calorie equation may seem simple, but evidence suggests that there are other mechanisms in play when considering the calories in vs. calories out approach to weight loss. According to researchers, there are certain factors that complicate the process.??

For example, the researchers note that hunger hormones increase during and after the weight loss process. In addition, as you lose weight, your BMR decreases. So unless you increase your daily PA, you'll need to re-evaluate the calories in/calories out equation regularly to make sure you are consuming the right number. And lastly, counting calories can be tedious and inexact.

In short, researchers suggest that even though counting calories and adhering to a calorie deficit may be effective (especially in the short term), certain mechanisms can reduce your metabolic rate and increase your calorie intake, which might cause you to regain any lost weight. There may be other strategies, such as focusing on macronutrient intake, that are more effective for some people.??

The key, say some scientists, is personalization. That is, finding a strategy that works for you.?? One way to fine-tune the best program for you, is to work with a registered dietitian.

5 Ways to Cut Calories

Reducing your calorie intake is one way to lose weight. Calories in vs. calories out may work for you if you know how many calories you need to lose weight and you are interested in finding ways to reduce your calorie intake. In addition, lifestyle changes, such as mindful eating, exercise, and other behavioral practices will help to facilitate weight loss and reduce the risk of weight regain.

People who are most successful are able to maintain the pleasure of eating without feeling deprived. If you start with small adjustments to your meals and your daily activity level, you are likely to feel motivated. Drastic changes can often be unsustainable. Here are a few steps you can take to create a calorie deficit.

Increase Daily Steps

Walk more each day. You don't even have to work out to increase your step count. Just make small adjustments to your routine. For example, park further away from your office or workspace so you have to add extra steps to get to the front door. Take the stairs instead of the elevator to your apartment. Take the dog for a walk after dinner. Research shows that walking 30 minutes per day on most days of the week can help to boost your health in numerous ways during weight loss.??

Reduce Portion Sizes

To reduce your portions, considering serving yourself one less scoop of food or a slightly smaller portion than what you are used to. To fill the void, add some non-starchy vegetables for more volume and fiber and fewer calories. Or use a smaller plate. Using a smaller plate will reduce the serving of food, but you'll still feel like you are eating a healthy serving because your plate will be full.

It may also be helpful to familiarize yourself with what a serving size is. For example, a serving of starch is about the size of your fist. A serving of protein is about the size of the palm of your hand.

Swap High-Calorie Drinks

Many of us consume sugar-sweetened beverages each day. In fact, data collected by the Centers for Disease Control indicates that over 50% of Americans consume at least one sugary beverage each day (although exact numbers vary by geographical area). Consumption of sugary drinks is linked to less healthy behaviors and may contribute substantial calories to your daily total.?? If you can drink water instead, you can cut 100 or calories or more from your daily intake.

Skip Condiments and Sauces

You can reduce the calories in your sandwich at lunchtime by avoiding mayonnaise or other high-fat spreads. And if you can avoid creamy sauces on your pasta or chicken dishes you'll cut fat and calories even more.

Start an Easy Exercise Program

If you want to burn more calories, you don't necessarily have to go to the gym every day or work out to the point of exhaustion. Instead, start an easy exercise program at home and commit to a 20-minute session in the comfort of your living room. A small amount of exercise can make a big difference in the way your body looks and feels. In the end, consistency matters most.

A Word From Verywell

The calorie equation isn't new or fancy or trendy, but it can be effective for some people. You don't need to pay for an expensive plan for weight loss to occur, but for many people, investing in a meeting with a registered dietitian may help them develop a personalized plan to reach a healthy weight. While there are many products and plans that can help you stick to a calories in vs. calories out lifestyle, you don't have to have them to slim down.

Was this page helpful?
Article Sources
Verywell Fit uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Benton D, Young HA. Reducing calorie intake may not help you lose body weight.?Perspect Psychol Sci. 2017;12(5):703-714. doi:10.1177/1745691617690878

  2. Koliaki C, Spinos T, Spinou Μ, Brinia ΜE, Mitsopoulou D, Katsilambros N. Defining the optimal dietary approach for safe, effective and sustainable weight loss in overweight and obese Adults.?Healthcare (Basel). 2018;6(3):73. Published 2018 Jun 28. doi:10.3390/healthcare6030073

  3. Bond Brill J, Perry AC, Parker L, Robinson A, Burnett K. Dose-response effect of walking exercise on weight loss. How much is enough? Int J Obes Relat Metab Disord. 2002 Nov;26(11):1484-93. doi:10.1038/sj.ijo.0802133

  4. Get the Facts: Sugar-Sweetened Beverages and Consumption. Centers for Disease Control and Prevention. Updated October 2, 2020