Calorie Deficit Calculator

Calculate exactly how many calories you need to eat to lose weight. Get your personalized daily calorie target, recommended macros, and see how long it will take to reach your goal.

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What is a Calorie Deficit?

A calorie deficit occurs when you consume fewer calories than your body burns throughout the day. This is the fundamental principle behind weight loss - when you create a deficit, your body must tap into stored energy (primarily body fat) to make up the difference.

For example, if your body burns 2,000 calories per day (your TDEE) and you eat 1,500 calories, you have a 500-calorie deficit. Over a week, this adds up to 3,500 calories - roughly equivalent to one pound of body fat.

The Calorie Deficit Formula

Calorie Deficit = TDEE (calories burned) - Calories Consumed

Daily Calorie Target = TDEE - Desired Deficit

How Many Calories Should I Eat to Lose Weight?

The number of calories you should eat depends on your maintenance calories (TDEE) and how quickly you want to lose weight. Here's a general guide:

Slow Weight Loss (250 cal deficit)

Lose 0.25 kg (0.5 lbs) per week. Easiest to maintain, preserves muscle, minimal impact on energy levels.

Moderate Weight Loss (500 cal deficit) - Recommended

Lose 0.5 kg (1 lb) per week. The gold standard for sustainable weight loss. Balances results with adherence.

Aggressive Weight Loss (750 cal deficit)

Lose 0.75 kg (1.5 lbs) per week. Faster results but more challenging. May experience hunger and fatigue.

Maximum Weight Loss (1000 cal deficit)

Lose 1 kg (2.2 lbs) per week. Very difficult to sustain. Risk of muscle loss and metabolic adaptation. Not recommended for extended periods.

Minimum Safe Calorie Intake

Regardless of your deficit goals, there are minimum calorie thresholds you should not go below without medical supervision:

Women

1,200

minimum calories/day

Men

1,500

minimum calories/day

Going below these minimums can lead to nutrient deficiencies, muscle loss, metabolic slowdown, hair loss, and other health issues. Our calculator automatically warns you if your target falls below safe levels.

How This Calculator Works

Our calorie deficit calculator uses a scientifically-validated approach to determine your personalized weight loss plan:

Step 1: Calculate Your BMR

Using the Mifflin-St Jeor equation, we calculate your Basal Metabolic Rate - the calories your body burns at rest.

Step 2: Calculate Your TDEE

We multiply your BMR by an activity factor to get your Total Daily Energy Expenditure - your maintenance calories.

Step 3: Apply Your Deficit

We subtract your chosen deficit (250-1000 calories) from your TDEE to get your daily calorie target.

Step 4: Calculate Timeline

We divide your total weight to lose by your weekly loss rate to estimate how long it will take to reach your goal.

Tips for Successful Weight Loss

1

Track Everything

Studies show that people who track their food intake lose significantly more weight. Use an app like BiteKit to make tracking easy.

2

Prioritize Protein

Eating adequate protein (0.7-1g per pound of body weight) helps preserve muscle mass and keeps you feeling full longer.

3

Be Patient

Weight fluctuates daily due to water, sodium, and other factors. Focus on the weekly trend rather than daily weigh-ins.

4

Adjust as Needed

Recalculate your calories every 10-15 pounds lost. As you lose weight, your TDEE decreases, requiring smaller portions.

Common Calorie Deficit Mistakes

Avoid these common pitfalls that can derail your weight loss progress:

  • Too aggressive too fast: Starting with a maximum deficit often leads to burnout. Start moderate and adjust as needed.
  • Not weighing food: Eyeballing portions can lead to 20-50% more calories than you think. Use a food scale for accuracy.
  • Forgetting liquid calories: Sodas, juices, and alcohol can add hundreds of hidden calories to your daily intake.
  • Eating back exercise calories: Fitness trackers often overestimate calories burned. Be conservative with exercise adjustments.
  • Weekend overeating: Two days of overeating can erase five days of progress. Consistency is key.

Frequently Asked Questions

What is a calorie deficit?

A calorie deficit occurs when you consume fewer calories than your body burns. This forces your body to use stored energy (fat) for fuel, resulting in weight loss. For example, a 500-calorie daily deficit typically leads to about 1 pound of weight loss per week.

How many calories should I eat to lose weight?

To lose weight safely, subtract 500-1000 calories from your TDEE (maintenance calories). A 500-calorie deficit is recommended for sustainable weight loss. Never go below 1,200 calories for women or 1,500 calories for men without medical supervision.

How long will it take to lose weight?

With a 500-calorie daily deficit, expect to lose about 1 pound per week. Our calculator provides personalized timeline estimates based on your weight loss goals and chosen deficit level.

Is a 1000 calorie deficit safe?

A 1000-calorie deficit is generally the maximum safe deficit, leading to about 2 pounds per week loss. However, it's difficult to sustain and may cause muscle loss. Most experts recommend starting with a moderate 500-calorie deficit.

Why am I not losing weight in a calorie deficit?

Common reasons include inaccurate calorie tracking, underestimating portions, water retention, or metabolic adaptation. Try recalculating your TDEE, measuring food precisely, and tracking consistently for 2-3 weeks before adjusting.

What is the minimum calories I should eat?

Health experts recommend not going below 1,200 calories per day for women and 1,500 calories per day for men. Our calculator warns you if your target falls below these safe minimums.

Ready to start your weight loss journey?

BiteKit makes hitting your calorie target effortless. Log meals with your voice or text and let AI calculate the nutrition for you.

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