What Is a Calorie Deficit, and Is It a Healthy Way to Lose Weight?

There are many approaches to weight loss. One very popular method is following a plan to put you into a calorie deficit. Read on to learn about what that entails, how to do it safely, what potential risks to be aware of, and what it looks like in real life. 

So, What is a Calorie Deficit? 

For background, a calorie is a unit of energy—a measurement of how much energy we get from food and beverages. Understanding calorie expenditure, the amount of calories you burn in a day, is crucial for managing your body’s energy balance. There are three parts to calorie expenditure:

• Resting energy expenditure (REE): The calories your body needs for the basic functions that keep you alive, such as breathing and blood circulation. You’d need this amount of energy if you just laid in bed for the day. Sometimes called the Basal Metabolic Rate. 
• Thermic effect of food (TEF): The calories expended through the process of digesting, absorbing, and metabolizing the food you eat. 
• Activity energy expenditure (AEE): The calories you burn during movements. This includes intentional exercise and things like fidgeting, doing chores and other tasks, or walking around throughout the day. 

A calorie deficit, where you consume fewer calories than you burn, is a powerful tool for weight management. If someone expended 2000 calories in a day, they’d need to consume 2000 calories per day to maintain their current weight. If they consumed less than 2000 calories or started burning more than 2000 calories without changing their caloric intake, this would result in weight loss. This is due to the stress placed on the body by this deficit, a key factor in weight management that you can control.  

It’s important to know, however, that many factors can contribute to weight fluctuations, such as hormones, hydration status, physical activity, digestion, sleep deprivation, stress levels, certain medications, underlying health conditions, and/or genetics. 

Safely Using A Calorie Deficit For Weight Loss

Research suggests that a calorie deficit of about 300-500 calories per day can lead to weight loss of about a pound per week. This could look like eating that many fewer calories, increasing energy expenditure, or a combination of smaller changes to eating and exercise habits that result in the desired calorie deficit. 

You can use formulas or online calculators that do the math for you to calculate your calorie needs. Lauren Harris-Pincus, MS, RDN, says that once you find out how many calories it takes to maintain your current weight, you can then calculate your deficit range. 

“The simplest way to determine a calorie deficit is to use a tool like Mifflin-St Jeor to determine your total energy expenditure based on your height, weight, gender, age, and activity level. It’s not perfect, but it’s a good place to begin. Subtract 300-500 calories off that number for a starting point that may yield a pound or so of weight loss per week.” 

However, this number can change significantly as someone loses weight. Additionally, because our bodies are all so different and so many factors can influence weight, the exact weight changes someone experiences can vary. If you feel like you’re in your target calorie deficit but the math doesn’t seem to be math-ing, look at what may be slowing your weight loss efforts. It might not even be what or how much you’re eating. 

However, be mindful that less is not always more when it comes to calorie intake. “Consuming fewer than 1200 calories per day is not advisable because it will be very difficult to meet your nutrient needs, and you actually want to live and enjoy your life,” says Harris-Pincus. She also recommends avoiding dipping below your basal metabolic rate. 

There is definitely a sweet spot. When someone attempts to be in a significant calorie deficit for too long, the stress can actually prompt the body to slow metabolism. Something else to consider: you could take a different approach that doesn’t focus on calories. 

Kim Shapira, a functional registered dietitian and nutrition therapist says, “I wouldn’t ever recommend calorie counting. Our body is in constant change. The emphasis has to be on overall well-being and long-term sustainable results rather than monitoring calories.” Instead, she encourages paying attention to your appetite and eating when you’re hungry. “Start with half of your normal portion and wait fifteen minutes (so leptin can communicate with your brain) to see if your body needs more fuel.”

“By starting with half of your normal portion and giving your body time to see if it needs more,” says Shapira, “you are already creating a calorie deficit- without having to count, measure, or restrict. Instead, you are focused on what and when your body needs fuel.” 

If someone doesn’t get hungry at this point, she says, this is a sign that they are generally eating more than they need “or their body fat-to-muscle ratio is out of balance, and they need to eat smaller, more frequent meals to increase their metabolism while also moving more.” She generally recommends striving for 10,000 steps per day. 

Risks of a Calorie Deficit

There are some potential downsides to a calorie deficit. Harris-Pincus explains, “It’s important to note that not all calories are created equal. An ideal diet should focus on meals and snacks with lean proteins, fiber-rich carbohydrates, and unsaturated fats. Stick with mostly whole foods like fruit, veggies, beans, whole grains, nuts, seeds, lean proteins, and low/nonfat dairy products or fortified plant-based dairy alternatives like soy milk. It’s tempting when calorie counting to use packaged products and meals that have clear calorie labeling, and that’s ok some of the time, but ideally, the majority of foods should be nutrient-rich and focused on protein and fiber.”

Shapira points out that striving for a calorie deficit without considering your overall nutrient needs can lead to issues such as “nutrient deficiencies, muscle loss, slowing down your metabolism, fat gain, hormone imbalances, anxiety, depression, weight gain, binge eating, and fatigue.” 

Harris-Pincus says, “Calorie counting and pursuing a calorie deficit for weight loss is not recommended for anyone who has a history of disordered eating or an active eating disorder, pregnant or breastfeeding people, or growing children. Speak to a healthcare provider if you have any medical history that might be contraindicated for calorie counting or intentional weight loss.”

Simple Tips for Creating A Calorie Deficit

• Make small changes. For example, if you were aiming for a 300-calorie deficit, you could spend 150 additional calories and consume 150 fewer calories per day. Harris-Pincus points out that these changes can be very approachable, and you don’t have to obsessively track calories. “It’s fairly simple to assess your diet as a whole and figure out ways to reduce calories without painstakingly counting. For example, swapping out a sugar-sweetened soda for an unsweetened beverage can save as much as 200 calories per occasion. Measuring cooking oil, salad dressing, and other condiments can save significant calories over what you may have been using before.”
• Stay in touch with your appetite. It’s also vital to stay tuned in to your body and stay in touch with your appetite and fullness cues, says Shapira. “Our appetite and needs will change for sure. Whether you have 5 pounds or 15 or 40 pounds to lose based on your body fat percentage—over time as you become more metabolically active meaning you have now more muscle-to-fat ratio—you will be hungrier. This is a great sign. Being hungry, getting hungry means your body is functioning properly.”
• Track body fat versus total weight. She also encourages using a scale that tracks body fat percentage rather than just your total weight. “Make sure that as you are losing weight you are losing fat and not muscle,” she explains. Building and maintaining muscle is important for supporting metabolic health and reaching and maintaining a healthy weight for your body. 

1-Day Sample Menu 

This sample menu outlines a 1500-calorie daily eating plan. It’s designed as a starting point for individuals aiming to create a calorie deficit for weight loss. Keep in mind that your specific needs may vary, and you may need to adjust your calorie intake accordingly.

While this plan meets the 1500-calorie goal, it also prioritizes protein, fiber, and healthy fats to support overall well-being. If you find yourself feeling excessively hungry or unsatisfied, consider these factors and potentially adjust your calorie intake slightly.

• Breakfast: Yogurt Bowl: ¾ cup low-fat plain Greek yogurt (120 calories) with ¾ cup berries (60 calories), 1 tablespoon chia seeds (60 calories), and 2 teaspoons almond butter (70 calories) = 310 calories
• Lunch: Salad: 3 cups mixed greens (20 calories) with 8 cherry tomatoes (20 calories), 1 cup sliced cucumber (20 calories), 1/2 cup cooked chickpeas (120 calories), 2 hard-boiled eggs (140 calories), 5 olives (30 calories), 1 teaspoon olive oil (90 calories), 1 -2 teaspoons red wine vinegar (0 calories) = 440 calories 
• Afternoon Snack: Veggies and guac: ¼ cup guacamole (120 calories) and 1 sliced bell pepper (30 calories) = 150 calories 
• Dinner: Baked Salmon: 4 oz baked salmon (180 calories) with 1 cup broccoli roasted (35 calories) in 1 teaspoon olive oil (45 calories) and 1 medium baked sweet potato (140 calories) with 1 teaspoon butter (35 calories) = 435 calories 
• Dessert: Chocolate fix: 1 square of dark chocolate = 50 calories
• Extras: One 12-ounce latte with skim milk = 100 calories 

Total calories: 1,485 calories 

Bottom Line

A calorie deficit is when you consume fewer calories than you expend. As a weight-loss tool, studies suggest aiming for a deficit of 300-500 calories per day can help you lose a pound per week, but smaller deficits than that can still be meaningful, and fewer calories is not always better. 

While some people may find it helpful to count calories, for others it may be more beneficial to look at small tweaks to make in day to day eating patterns and behaviors. Always listen to your body and don’t be afraid to get support from a licensed provider such as a registered dietitian to help you come up with an individualized plan to help you reach your goal and maintain a healthy weight for your body.