A person can create a calorie deficit by not consuming as many calories as they need to maintain their body weight during the course of a day or week. Over time, this calorie reduction can lead to weight loss.
This article covers everything a person needs to know about calorie deficits and weight loss.
What is a calorie deficit?
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A calorie deficit occurs when the number of calories a person consumes in a day is smaller than the number of calories they burn.
The body needs to burn a certain number of calories to perform all its functions each day.
How many calories a person needs each day varies based on their:
Here are some estimated calorie needs for adults aged 19 years and over:
A person can create a calorie deficit by reducing the number of calories they eat, increasing their activity levels, or both.
Is a calorie deficit enough to lose weight?
Maintaining a calorie deficit is an important part of weight loss, but it is not the whole picture. This is because calories are not the only thing to affect weight.
To lose 12 pounds (lb) per week, a person would need to eat 5001,000 calories fewer than the number of calories their body needs per day.
If a person is sedentary, meaning that they only move as much as they need to live independently but do not exercise or engage in other physical activities, they should start to get 30 minutes of exercise each day, if possible.
Also, the Centers for Disease Control and Prevention (CDC) state that cutting calories does not necessarily mean feeling unsatisfied at meals.
A person can replace some higher calorie foods with lower calorie foods, increase their water intake, and eat more fiber to feel full.
How to calculate calorie needs
There are several ways to determine how many calories a person normally burns in a day.
For example, they can opt to calculate their daily calorie needs manually or find an online calculator.
To perform a manual calculation, moderately active people can multiply their current body weight by 15 to estimate how many calories they would need each day.
Then, to determine how many calories they should consume for a healthful calorie deficit, they can subtract roughly 500 calories from that number. However, people should ensure that they do not consume too few calories. It is also important to note that exercising can also contribute to a calorie deficit.
A person can also use their basal metabolic rate (BMR) and activity levels to determine their current caloric needs. They can use one of the following formulas to determine their BMR, according to their sex:
Once a person has their BMR, they can use one of the following formulas, based on their activity levels, to determine their caloric need:
People can also talk with their doctor or nutritionist for the most accurate caloric intake estimates. These professionals can tailor the estimate based on the person and their lifestyle.
How to create a calorie deficit
Once a person knows how many calories they need each day or week, they can work on creating a calorie deficit.
One lb of body fat contains about 3,500 calories. For a person to lose 1 lb of fat in a week, they would need a deficit of 3,500 calories, or 500 calories per day, over that time. To lose 2 lb, a person would need a deficit of about 7,000 calories.
However, it is not advisable for a calorie deficit to exceed 7,000 calories per week.
One component in creating a calorie deficit is changing what a person eats and drinks each day. A person should focus on foods that are rich in nutrients but low in calories.
According to the Dietary Guidelines for Americans 20202025, a healthful eating pattern with fewer calories should include:
A person should also avoid consuming sugary drinks and trans fats.
They may also wish to increase the amount of water they drink, which will help them stay hydrated and replace any sugar sweetened beverages they usually consume.
An important part of weight loss is exercise. A person who is not active at all should try to increase their daily activity levels, if they can.
This can include activities such as:
The CDC recommend that a person can do the following activities to meet moderate physical activity guidelines:
The more physically active a person is, the more calories they will burn.
This increases the number of calories they need, which can make creating a deficit easier.
Other things to consider
Cutting calories is an important part of weight loss, but it is not the only consideration to make.
Physical activity is important for health beyond weight loss. People who are sedentary and move very little throughout the day should try to increase their daily activity levels, if possible. This can include exercising, playing sports, or participating in activities that require movement, such as hiking.
However, people should avoid cutting too many calories. Cutting out about 5001,000 calories per day is a good range to aim for. People should also avoid losing more than 2 lb each week.
It is also important to note that counting calories is not necessary for weight management, and, in some cases, it may be counterproductive or harmful.
Risks of eating too few calories
If a person cuts too many calories and does not get enough necessary nutrients, they can experience some health problems.
The body needs a minimum number of calories to function properly. Cutting too many can increase the risk of health issues, including:
Some symptoms of not consuming enough calories include:
Before cutting calories, a person should talk with their doctor or nutritionist. People with specific health conditions, such as diabetes, may need specialized diets to help them manage their condition.