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Nutrition

How to Calculate Your Calorie Deficit

You know a calorie deficit is what drives fat loss, but you're not sure how to actually set one up for yourself. Dr. Joey walks through exactly how to find your number and how far below it to eat.

Dr. Joey Munoz
Dr. Joey Munoz, PhD
· August 21, 2026 · 8 min read
Calorie Deficit Explained: The Only Way to Lose Fat
Quick Answer

First find your maintenance calories, the amount that keeps your weight stable, using an online calculator, a body weight multiplier, or the most accurate method: tracking calories and weight for two weeks. Then eat 10 to 25% below that number depending on your experience level and goals.

Every weight loss diet that actually works does so for one reason: a calorie deficit. The real question isn't whether you need one, it's how to actually set one up correctly and stick to it.

Let's walk through exactly how to find your maintenance calories and how far below that number you should actually eat.

Step One: Find Your Maintenance Calories

Your maintenance calories are simply the amount you need to eat to keep your body weight stable, also known as your total daily energy expenditure. There are three ways to estimate this, and none of them is perfect, they're all a starting point you adjust from.

MethodHow It Works Online TDEE CalculatorSearch "TDEE calculator," enter your weight, height, gender, and activity level for an estimate. Body Weight MultiplierMultiply your body weight by an activity factor (see below) for a rough number. Direct Tracking (Most Accurate)Track calories and weight for 2 weeks. Whatever keeps your weight stable is your real maintenance number.
Body Weight Multiplier Method
Sedentary (little exercise, desk job)Weight × 11-12
Moderately active (trains regularly, some daily movement)Weight × 14-16
Extremely active (trains 6-7x/week + active job)Weight × 18-20

The third method, direct tracking, is the slowest but the most accurate, because it's a real measurement of your body rather than a population-based estimate. Track your food intake and your weight for two weeks. If your weight stays the same while eating, say, 2,500 calories a day, that's your real maintenance number.

Step Two: Decide How Big Your Deficit Should Be

Once you know your maintenance calories, you need to eat below that number to lose fat. How far below depends on your experience, your goals, and how much weight you actually want to lose.

Deficit SizeBest For Slow (10-15% below maintenance)Beginners, people with less weight to lose, or anyone prioritizing muscle growth alongside fat loss. Moderate (15-20% below maintenance)More experienced people with solid habits already in place who want a somewhat faster rate. Large (20-25% below maintenance)Situational use only. Comes with more hunger and higher risk of muscle loss.
You don't want to go into a super drastic deficit that feels really hard to maintain. It's better to take a slow and controlled approach.

If you're newer to dieting, have less than 10 or 15 pounds to lose, or care about building muscle alongside fat loss, stick with a slow deficit. Reducing calories too aggressively makes it harder to recover from training and increases the odds that some of what you lose is muscle, not just fat.

Key Takeaways
  • Maintenance calories can be estimated with a TDEE calculator, a body weight multiplier, or measured directly by tracking for two weeks.
  • Direct tracking is the most accurate method since it reflects your actual body, not a population average.
  • A slow deficit of 10-15% below maintenance suits beginners and anyone prioritizing muscle alongside fat loss.
  • A moderate 15-20% deficit fits more experienced people with established habits who want faster results.
  • Larger deficits speed up weight loss but increase hunger and the risk of losing muscle along with fat.

A calorie deficit isn't complicated once you break it into these two steps: find your real maintenance number, then choose a deficit size that matches your experience and goals, not just the fastest number you can find.

Frequently Asked Questions

How do you calculate your maintenance calories?

There are three methods: using an online TDEE calculator with your stats, multiplying your body weight by an activity factor, or the most accurate method, tracking your calories and weight for two weeks to see what number keeps your weight stable.

How big should my calorie deficit be?

A slow deficit of 10 to 15% below maintenance is best for beginners, people with less weight to lose, or anyone prioritizing muscle building alongside fat loss. A moderate 15 to 20% deficit suits more experienced people with solid habits already in place.

Is a bigger calorie deficit always better for faster results?

Not necessarily. A larger deficit does speed up weight loss, but it also increases hunger, makes gym performance and recovery harder, and raises the risk of losing muscle along with fat, which works against long-term results.

Why is tracking calories for two weeks the most accurate way to find maintenance?

Online calculators and body weight formulas are estimates based on averages, not your specific body. Tracking your actual intake while your weight stays stable gives you a real, personalized number rather than a general approximation.


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