A calorie deficit diet consists of fewer calories than you need to maintain your weight.
However, since everyone has different calorie needs, you may wonder how much of a calorie deficit is right for you.
At the same time, you may also wonder if it’s possible to build muscle on a calorie deficit diet.
This article explains how to calculate your calorie deficit, whether you can gain muscle in a calorie deficit, and what to do if you’re following a calorie deficit diet but not losing weight.
What is a calorie deficit diet?
All diets for fat loss work by creating a calorie deficit, meaning they consist of fewer calories than you need to maintain your body weight.
These diets may differ in their composition of macronutrients, the foods they allow, or meal frequency, but they all work by creating a calorie deficit.
Whether you can follow the diet long-term and develop healthy behaviors to maintain the fat loss is a different story.
Most calorie deficit diets range from 1,200–1,800 calories, creating a daily calorie deficit of anywhere from 300–800 calories for most people.
How do you calculate a calorie deficit?
Before you can calculate your calorie deficit, you must know your total daily energy expenditure (TDEE) — the number of calories you need to maintain your weight.
There are three main components of TDEE (1):
- Resting energy expenditure (REE): Also known as resting metabolic rate, REE represents the amount of energy you expend at rest. REE is the largest component of your TDEE.
- Thermic effect of food (TEE): TEF refers to the energy needed to digest and process the food you eat. Protein requires the most energy to digest and process, followed by carbs and fats.
- Activity energy expenditure (AEE): AEE refers to the energy you expend during both sports-like exercise and nonexercise activities like mowing the yard or walking the dog.
If you provide your body with fewer calories than it needs to support the three components of TDEE, you put your body in a calorie deficit.
Conversely, if you provide your body with more calories than it needs to support these components, you put your body in a calorie surplus.
To calculate your TDEE, you can use online TDEE calculators like the Body Weight Planner from the National Institue of Health, which take into account factors like your weight, height, gender, age, and physical activity level (2).
Once you have your TDEE, subtract 300–500 to calculate the number of calories you should eat to lose fat.
A calorie deficit of 300–500 calories is sufficient for most people to lose fat at a healthy and sustainable rate.
For example, if your TDEE is 2,000 calories, you should eat 1,500–1,700 calories per day.
You can create a calorie deficit by restricting your calories, increasing your physical activity level, or both.
Can you gain muscle in a calorie deficit?
A calorie surplus is optimal for building muscle.
This is why bodybuilders generally focus on building as much muscle as possible with a high-calorie diet during the bulking phase and then reduce calories to achieve a calorie deficit and reduce body fat during the cutting phase.
However, it’s still possible to gain muscle in a calorie deficit through body recomposition.
In one study, females with obesity and limited training experience who followed a roughly 600-calorie deficit diet and resistance-trained 2–3 times per week for 16 weeks were able to simultaneously lose body fat and gain lean body mass (5).
Similarly, overweight men who followed a calorie deficit and engaged in an intense training regimen for 6 weeks gained 2.6 pounds (1.2 kg) of lean body mass and lost 9.6 pounds (4.8 kg) of body fat (6).
Still, while it’s possible to build muscle in a calorie deficit, the muscle gains you could achieve with a calorie surplus are much greater (5).
Also, people who are overweight or obese and with minimal training experience are likely able to gain more muscle in a calorie deficit than those who are at a healthy weight and regulary exercise (7).
What to do if you’re not losing weight
If you believe you’re in a calorie deficit but not losing weight, you’re probably not in a calorie deficit.
Although tracking your calories is not required for weight loss, doing so for 3–5 days can help you determine whether you’re in a deficit of 300–500 calories based on your estimated TDEE.
Keep in mind that you will also have to regularly recalculate your TDEE and lower your daily calorie goal as you lose weight.
This is because the less you weigh, the fewer calories you burn at rest and during physical activity.
A 10% loss in body weight — or about every 15–20 pounds (6.8–9.1 kg) you lose — is significant enough to recalculate your TDEE and lower your daily calorie goals to maintain a healthy calorie deficit for continued fat loss.
Reverse dieting is also a strategy to help increase your metabolism and jumpstart fat loss.
Tips for staying in a calorie deficit
Here are a few tips that will make maintaining a calorie deficit easier and more effective for fat loss.
Eat a high-protein diet
Protein has three main benefits for fat loss (10):
- Protein increases metabolic rate by 15–30%, significantly more than carbs (5–10%), and fat (0–3%).
- Protein increases feelings of fullness and decreases hunger more than carbs or fats.
- Protein spares muscle loss during a calorie deficit, helping to preserve the calories you burn at rest and during exercise.
Good sources of protein include:
Evenly distribute your protein intake across 4–6 meals each day for the best results (11).
Fill up on nutrient-dense foods
Nutrient-dense foods provide high amounts of nutrients relative to calories.
Eating mostly nutrient-dense foods is important for health but also when you’re following a calorie-deficit diet to ensure you’re getting the nutrients your body needs.
The best nutrient-dense foods include:
- lean proteins
- low-fat dairy
- nuts and seeds
- beans and peas
Limit your consumption of foods that are highly processed since they also tend to be high in calories.
Examples of highly processed foods to limit include:
- sugary drinks like soda and sweetened tea
- most breakfast cereals
- cakes, cookies, and muffins
- ice cream and other dairy desserts
- chocolate and candies
- salty snacks like chips
- processed meats like sausages and deli meats
You may be able to include some of these foods using a flexible approach to dieting depending on your calorie goal.
However, exercise while in a calorie deficit becomes especially important for ensuring the weight you do lose comes primarily from fat — not muscle (16).
Aim to include muscle strengthening exercises that target your major muscle groups — back, chest, shoulders, arms, core, and legs — at least three times per week (17).
Including some moderate aerobic activity like brisk walking or riding a bike in your routine is also beneficial.
Don’t skimp on sleep
Sleep is an underappreciated aspect of good health.
Unfortunately, a lack of good sleep can negatively affect the effectiveness of your calorie deficit or ability to maintain it.
One study showed that just one hour of sleep restriction for five nights led to less fat loss in people following a calorie deficit diet compared to those who were following the same calorie deficit diet but were not sleep-restricted (18).
The study also showed that the sleep-restricted group had a significant increase in ghrelin, commonly known as the “hunger hormone.”
Higher levels of ghrelin have been shown to increase the likelihood of fat regain and is one of the reasons some people fail to maintain their weight loss long-term (19).
Aim for 7–9 hours of sleep per night and practice good sleep habits like maintaining a consistent sleep schedule and reducing your exposure to blue light from your phone or TV before bedtime (20).
The bottom line
A calorie deficit diet consists of fewer calories than you need to support the three components of TDEE.
A healthy and sustainable calorie deficit for fat loss is 300–500 calories.
If you’re following a calorie deficit diet but not losing weight, closely track your calorie intake for 3–5 days to determine whether you’re truly in a 300–500 calorie deficit.
While you can build muscle in a calorie deficit, it’s not optimal.
To increase the effectiveness and sustainability of your calorie deficit, eat a high-protein diet, fill up on nutrient-dense foods, resistance train, and don’t skimp on sleep.