Calorie deficit guide: how much to eat to lose weight

If you're trying to lose weight with diet and exercise, eating in a calorie deficit may help you reach your weight loss and wellness goals.

Calories represent the amount of energy your body obtains from foods and drinks. When you’re eating in a calorie deficit, you take in fewer calories than you burn—either by eating fewer calories, increasing your activity levels, or a combination of both. 

While a calorie deficit can help you lose weight, it’s important to do so in a healthy way that works best for your body. Extreme calorie restrictions can harm your health and may contribute to an unhealthy relationship with food. 

This guide tells you everything you need to know about eating in a calorie deficit, including how to calculate your energy needs, safe and effective calorie deficit ranges, potential risks, and how to monitor your progress.

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Calories are the energy source your body uses for various functions, like breathing, walking, and digesting the food you eat. 

When you consume around the same number of calories you burn every day, your body weight will generally stay the same. If you’re trying to lose weight, you may need to take in fewer calories than you burn. 

This is known as a calorie deficit. For example, a person taking in 1,800 calories per day but burning 2,000 is in a calorie deficit. 

When you’re in a calorie deficit, your body is forced to break down stored body fat for energy, which can lead to weight loss for some people. 

A calorie deficit can be achieved in two ways: 

• Reducing your daily calorie intake

• Increasing your energy output by being more physically active 

A calorie deficit is only meant to be used for a limited time to induce weight loss. Most people follow reduced-calorie diets for several months until they reach their weight loss goals. 

However, the amount of time you’ll need to spend in a calorie deficit depends on how much weight you want to lose. People who want to lose more weight may generally need to follow a lower-calorie diet for longer than those who have a smaller amount of weight to lose. 

No matter if you want to drop five or 100 pounds, it’s important to choose safe and sustainable methods to do so. This includes avoiding extreme diets and instead creating a healthy, balanced eating plan based on your specific needs and preferences. Eating in a calorie deficit isn’t about skipping meals or practicing extreme food restriction—it’s about eating nutrient-dense, whole foods to help fuel your body while you’re trying to lose weight.  

This balanced approach can support steady weight loss to help you reach and maintain your goals while reducing the risk of unpleasant—or potentially harmful—side effects. 

The first step in creating a calorie deficit is determining your individual calorie needs, which vary based on factors like your age, weight, height, and activity levels. 

After you figure out your average daily calorie needs, you can then subtract calories based on your weight loss goals. 

There are a few ways to determine your calorie needs and calculate your calorie deficit, including using an online calorie deficit calculator, manual calculation, and working with a healthcare provider. 

Using a calorie deficit calculator

Online calorie calculators can help find your total daily energy expenditure (TDEE), or the total number of calories your body burns daily, by having you plug in your height, body weight, and activity levels. 

TDEE includes your basal metabolic rate (BMR), which is the energy your body uses for life-sustaining processes such as breathing and circulating blood while you’re at rest. Your BMR accounts for 60 to 70% of your daily energy needs. 

Manual calculation method

If you’re interested in calculating your calorie needs on your own, you can use the Mifflin St. Jeor Equation. This is a formula that uses your height, weight, and age to calculate your BMR. 

Here are the equations for men and women:

• Men: calories per day = 9.99 (weight in kilograms/kg) +6.25(height in centimeters/cm) –4.92  (age) +5 

• Women: calories per day = 9.99 (weight in kg) +6.25(height in cm) – 4.92  (age) -161 

So, for a 50-year-old woman who stands at 5’6’’ and weighs 150 pounds, the equation would be:

• 9.99 (68 kg) +6.25(167.64 cm) – 4.92  (50) -161  = 1,320 calories per day

After determining your BMR, you then multiply this number by something called an activity factor. Activity factors are numbers that are based on your average daily activity levels—the more active you are, the greater the number:

• Sedentary: x 1.2 (very little or no exercise) 

• Lightly active: x 1.375 (light exercise less than three days per week) 

• Moderately active: x 1.55 (moderate exercise most days of the week) 

• Very active: x 1.725 (hard exercise every day)

• Extra active: x 1.9 (strenuous exercise two or more times per day)

The number you get as a result of this formula is your TDEE. Once you’ve determined your daily energy needs, you can subtract calories from that number to create a calorie deficit. 

Though the Mifflin St. Jeor equation is considered the most reliable method for calculating BMR, it’s important to note that it only gives you an estimation of your daily calorie needs, and may not be exact. 

This method does not account for the thermic effect of food (TEF), which is the number of calories your body uses to digest and absorb energy from foods and drinks.

TEF accounts for around 10% of your total daily energy expenditure, but it varies based on the composition of your diet. The TEF of protein, carbs, and fats are 20–30%, 5–10%, and 0–3%, respectively. For example, protein takes the most energy to digest, so someone following a high-protein diet will burn more calories than someone following a lower-protein diet. 

Seeking professional guidance

If you don’t feel comfortable calculating your energy needs and creating a calorie deficit on your own, a healthcare provider may be able to offer more guidance. 

Registered dietitians (RDs) and certain healthcare professionals, such as obesity specialists, can help calculate your energy requirements and develop a custom weight loss plan tailored to your goals and health needs. 

“An RD can help identify some key areas in your diet where calories can be decreased while ensuring you still get plenty of protein, fiber, healthy fats, and micronutrients,” says Daniel Preiato,  RD, CSCS. 

In some cases, medical professionals may have access to more accurate methods for determining calorie needs, such as indirect calorimetry, which measures both your oxygen consumption and carbon dioxide production during a set period. Indirect calorimetry is considered the “Gold Standard” for measuring calorie needs and is more accurate than online calculators or equations like Mifflin St. Jeor. 

To create a calorie deficit, you’ll need to reduce your calorie intake, increase your energy expenditure, or try a combination of both. 

Pairing a smaller calorie reduction (about 250 fewer calories per day) with increased physical activity may be a more sustainable option, and can help you feel less restricted in your diet. Plus, adding in or increasing physical activity can help improve other aspects of overall wellness, like heart health and mental health.

Diet considerations and tactics

When you’re trying to lose weight, choosing a healthy dietary pattern is key for helping you meet your goals. Increasing your intake of nutritious and filling foods high in protein and fiber and reducing your intake of highly processed foods can help you stick to your updated daily calorie goals. 

Although it’s not necessary to follow a specific diet, certain ways of eating have been shown to enhance weight loss and reduce hunger levels.

Increase your protein intake

Protein can support weight loss by slowing digestion, stimulating the release of satiety hormones, and decreasing appetite—which can all make eating in a calorie deficit easier. High-protein foods include chicken, Greek yogurt, legumes, and seafood. 

Following a high-protein diet may also help preserve muscle mass in a calorie deficit. A 2024 review of 28 studies found that increased protein intake significantly prevented muscle mass decline in adults with overweight or obesity who were trying to lose weight. 

Maintaining muscle mass is important for long-term weight loss maintenance as it can help preserve your BMR (the number of calories you burn at rest). Studies show that people who are trying to lose weight while gaining or maintaining their muscle mass need between 1-1.4 grams of protein per pound of body weight per day. 

Eat more fiber-rich foods

Like protein, fiber increases feelings of fullness, which can help you eat fewer calories. High-fiber foods include beans, fruits, vegetables, nuts, seeds, and whole grains. Men need between 30-38 grams of fiber per day, while women need between 21-25 grams per day, depending on age. 

Prioritize whole foods

Cutting back on ultra-processed foods—which are high in added sugar, refined carbs, and sodium—and opting for whole foods rich in protein, fiber, and healthy fats can reduce hunger levels and may decrease the need for snacking. 

Exercise and fitness in a calorie deficit

Getting regular exercise is critical for overall health, including the function of your heart and lungs. Increasing physical activity is an excellent way to improve your fitness levels, reduce disease risk, and torch some extra calories. 

You don’t have to sign up for intensive workout classes or join an expensive gym to get in an effective, calorie-burning workout. Walking, jogging, and yoga are just a few examples of exercises you can do on your own for free. 

Increasing your daily steps is one of the best ways to create a calorie deficit. Walking is accessible for most people and is a low-impact, beginner-friendly activity. You can track your energy output by keeping track of your steps with a FitBit or your smartphone. Studies show that you burn around one calorie for every 20 steps you take. A mile is roughly 2,000 steps, so walking three miles a day (6,000 steps) could burn around 300 calories. 

If your current activity levels are low, start by tracking your steps and taking one or two daily walks to create a calorie deficit. 

Preiato also recommends adding resistance training whenever possible. “In my experience, resistance training is vital to the weight loss process,” he says. “It helps you maintain or increase muscle mass, in turn increasing your BMR and allowing you to burn calories more efficiently.”

It can be tempting to try to lose weight quickly by creating a large calorie deficit, but most experts recommend a slower rate of weight loss between one to two pounds per week (or about four to eight pounds per month).

Creating a smaller calorie deficit and losing weight at a slower, steadier rate may also make it easier to maintain your diet and fitness plan.

“​​Research suggests that a moderate calorie deficit is much more sustainable for the long term when compared with very low-calorie diets,” says Preiato. “You may see great results on a very low-calorie diet initially, though they can be quite hard to stick to when your natural hunger cues prevail.”

For some people, a calorie deficit of around 500 calories per day may equate to a weight loss of about one pound a week or four pounds a month. 

To get to this calorie deficit, you could deduct 500 calories from your current calorie intake, or use a combination of reduced calorie intake and increased energy expenditure via regular exercise. For example, you might try a 250/250 method by cutting 250 calories per day and increasing your daily energy expenditure by 250 calories. This combination approach may help the calorie reduction feel more gradual and sustainable.

How long it takes a person to burn calories depends on factors like age, weight, and other health conditions, but some ways to burn 250 calories might include:

• 30 minutes of cycling

• 30-60 minutes of brisk walking or dancing

• 30-40 minutes of lap swimming

• 20-30 minutes of high-intensity interval training (HIIT)

When figuring out how many calories to deduct each day, it’s crucial to understand that cutting your calories too drastically can lead to unpleasant and even potentially dangerous side effects like extreme hunger, dizziness, and fainting. 

Extreme calorie restriction can also lead to compensatory changes in your body. If you cut too many calories too quickly, your body may respond by slowing down your metabolism or making other changes to help counteract the calorie deficit. This may include muscle loss, increased appetite, and reductions in BMR, which can make it harder to maintain weight loss long term. 

This is why it’s best to create smaller calorie deficits and to avoid diets that are very low in calories, such as those that provide less than 1,200 calories per day. 

When you’re eating in a calorie deficit, pay attention to how you feel. If you find that you have low energy levels or are experiencing dizziness, headaches, or intense hunger, you may need to increase your calorie intake. 

There are a few common mistakes that many people make when eating in a calorie deficit. These can increase the risk for unpleasant complications and may also make weight loss harder.   

• Eating too few calories. Cutting out too many calories can lead to extreme hunger, nutrient deficiencies, low mood, and decreased BMR, which can make it harder for you to reach your wellness goals. 

• Neglecting protein. Protein helps keep you full and is important for maintaining muscle mass. Inadequate protein intake can lead to muscle loss during weight loss, which negatively decreases your metabolic rate.

• Being too strict. Research suggests that being overly strict with your diet and avoiding certain foods can increase cravings. Studies also show that people who are overly restrictive with their diet are more likely to overeat highly palatable foods, like sweets and processed foods, than people who take a more flexible approach to eating.  

• Focusing on diet only. While diet is important when it comes to weight loss, other factors—like regular exercise, staying hydrated, and getting enough sleep—are crucial for overall health and body weight maintenance.

To design and maintain a calorie-deficit meal plan, you’ll need to keep track of your calorie intake and energy expenditure. While calorie and activity tracking isn’t meant to be done long term, it can help you stay on track when you’re in a calorie deficit. 

You can use an app like MyFitnessPal to track your calories and activity to ensure you’re hitting your daily goals. It can also help you stay within set macronutrient ranges, such as a high-protein eating pattern.

While calorie-tracking apps can be helpful in the short term, it’s important to note that their use may trigger or worsen disordered eating behaviors in some people. Therefore, it’s important to only track your calories when necessary. 

If you find yourself in a weight loss plateau or aren’t achieving your body composition goals, you may have to adjust your calorie intake or energy output. A healthcare provider, like a registered dietitian, can help you work through any setbacks you encounter and provide personalized recommendations based on your progress. 

In addition to weight loss, changing up your diet may help improve health in other ways. Losing excess body fat can reduce the number of risk factors for chronic diseases, like type 2 diabetes, elevated blood lipid levels, and high blood pressure. 

For example, research findings suggest that type 2 diabetes risk is reduced by 16% for every kilogram (2.2 pounds) of weight lost in people with overweight or obesity who have prediabetes. 

Eating a variety of nutrient-dense foods can also help boost your intake of vitamins, minerals, protein, and healthy fats. These changes can improve the overall quality of your diet, which may enhance mental and physical health. 

Though losing weight by eating in a calorie deficit can improve health in several ways, cutting calories too drastically comes with risks. 

“Cutting calories too much leaves you susceptible to various nutrient deficiencies, the most common being vitamin D, calcium, magnesium, iron, and B12,” Preiato says. “ Some other downsides include fatigue, muscle loss, moodiness, excessive hunger, and sleep disruptions.”

Additionally, taking in too few calories can negatively impact your BMR, which can make weight loss harder to maintain over time. 

When you’re eating in a calorie deficit, it’s important to watch out for signs that you may be under consuming calories, such as:

• Feeling dizzy upon standing

• Tiredness or low energy

• Extreme hunger

• Mood changes

These may be signs that you need to increase your calorie intake or scale back on your workout schedule.

Choosing a smaller calorie deficit can help to prevent these potential side effects. Though it may result in slower weight loss, a smaller reduction in calories can support safer weight loss and set you up for long-term success. 

If you’re underweight, have an eating disorder (or a history of disordered eating), or are pregnant or nursing, it’s best to avoid cutting calories or following a weight loss plan unless specifically recommended by a healthcare provider. 

While eating in a calorie deficit can be an effective and safe way for some people to drop extra body fat, weight loss may still be a struggle for some. If you find it hard to lose weight even when eating in a calorie deficit and exercising more, talk to your healthcare provider. 

Certain health conditions, like hypothyroidism and polycystic ovarian syndrome (PCOS), can make weight loss harder due to their impact on metabolism, hormones, appetite regulation, and more. A healthcare provider can rule out these and other conditions that impact body weight and recommend other treatment options if needed, including weight loss medications.  

It’s also a good idea to talk to a healthcare provider if you’re experiencing side effects like extreme hunger, mood changes, or fatigue. 

A healthcare provider can diagnose any underlying health issues and help you design a safe, sustainable diet and wellness plan specific to your health needs and goals.  

Eating in a calorie deficit may help you lose weight and reach your body composition goals, but it’s crucial to choose a healthy and safe diet plan that provides your body with enough calories and covers your nutrition needs.

• Create a calorie deficit by pairing a small to moderate calorie reduction (250-500 fewer calories per day) with increased exercise. This can help make your plan easier to stick to long term and set you up for success. 

• Try the 250/250 approach by cutting 250 calories per day and burning 250 calories with 30 minutes of cycling, swimming, or brisk walking. This will help create a calorie deficit of around 500 calories per day, which may lead to a weight loss of about one pound a week or four pounds a month. 

• Avoid extreme diets that provide less than 1,200 calories per day. These drastic calorie restrictions can cause potentially harmful side effects, create an unhealthy relationship with food, and may even make weight loss more difficult. 

• Creating a smaller calorie deficit and losing weight at a slower, steadier rate may help prevent compensatory changes that make long-term weight maintenance difficult, like muscle loss, increased appetite, and reductions in BMR, which often occur when following very low-calorie diets.

• Some people may need additional support. A healthcare provider can rule out underlying health issues that make weight loss difficult and give personalized recommendations for diet, exercise, and medications if needed.