How to calculate your caloric deficit

Losing weight comes down to a simple equation: burning more calories than you consume. But the practice is more nuanced. Too small a deficit doesn't show visible results; too aggressive a deficit triggers compensation mechanisms. This guide helps you find the sweet spot—a deficit that works without starving you.

Steps

1

Calculate your TDEE

You can't create a deficit without knowing how much you spend. Use the Mifflin-St Jeor formula with your activity factor. If your TDEE is 2,400 kcal, that's your reference point—the number of calories that maintains your current weight.

2

Choose your deficit level

Light deficit (250-300 kcal): slow but comfortable loss, ideal for beginners. Moderate deficit (400-500 kcal): loss of 0.4-0.5 kg/week, the most recommended. Aggressive deficit (600-750 kcal): faster results but risk of hunger, muscle loss, and relapse. Avoid deficits greater than 750 kcal.

3

Calculate your daily calorie goal

TDEE minus your chosen deficit. Example: 2,400 - 500 = 1,900 kcal/day. Check that this figure remains above your BMR (basal metabolic rate). If it's not, reduce the deficit—eating below your BMR slows down the metabolism and encourages muscle loss.

4

Plan your meals accordingly

Spread your 1,900 kcal over 3-4 meals with a priority on protein (it preserves muscle and keeps you full). Prefer nutrient-dense, low-calorie foods: vegetables, lean proteins, whole grains. Food volume matters for satiety.

5

Monitor your weight weekly

Weigh yourself every morning and calculate the weekly average. Ignore daily fluctuations (water, salt, digestion). Compare averages week to week. A loss of 0.3-0.7 kg per week means your deficit is working.

6

Adjust over time

As you lose weight, your TDEE decreases (less mass to fuel). Recalculate every 5 kg lost. If weight loss has stalled for more than 3 weeks, reduce by 100-150 kcal or add an activity session. Plateaus are normal—don't panic.

The science of caloric deficit

A deficit of 7,700 kcal theoretically corresponds to 1 kg of fat lost. In practice, it's rarely that linear: the body adjusts its metabolism, retains water, and the composition of what you lose varies (fat + some muscle). Adaptive thermogenesis can reduce your TDEE by 5-15% in response to prolonged dieting. This is why weight loss naturally slows down after a few weeks, even if you maintain the same deficit.

Safe deficit ranges

The American College of Sports Medicine recommends a loss of 0.5 to 1 kg per week maximum. Faster than that, you lose muscle, not just fat. Highly overweight individuals (BMI > 35) can handle a larger deficit at first, but most people should aim for 400-600 kcal deficit. For athletes, a deficit of 300-400 kcal is better to maintain performance and recovery.

Plateaus and how to overcome them

A plateau is a weight stagnation for 3 weeks or more despite maintaining a deficit. Possible causes: metabolic adaptation, water retention (especially in women during their cycle), underestimating portions, or overestimating exercise. Solutions: a week at maintenance calories (a 'diet break') can restart your metabolism. Slightly reducing sodium decreases water retention. Checking portions with a food scale often reveals hidden discrepancies.

FoodCraft Tip

Personalized deficit calculator

FoodCraft's caloric deficit calculator calculates your TDEE, applies your chosen deficit, and directly displays your daily goal. Three deficit levels are offered with expected results.

Meal planning with the right calorie count

FoodCraft's AI planning generates a week of meals directly calibrated to your calorie goal. Each day respects the deficit while varying dishes and maintaining good protein intake.

Essayez le calculateur associé

Calculer maintenant

Frequently Asked Questions

Is a 1,000 kcal deficit dangerous?
It's excessive for most people. Such an aggressive deficit leads to significant muscle loss, constant fatigue, uncontrollable cravings, and often a yoyo effect. Only severely obese individuals, under medical supervision, can temporarily handle such a deficit.
Should you create a deficit through diet or exercise?
Ideally both, but diet is more effective. Running for 30 minutes burns about 300 kcal—roughly one croissant. It's easier to just not eat the croissant. However, exercise is essential for preserving muscle mass during a deficit.
How long should you stay in a deficit?
Phases of 8-12 weeks followed by a maintenance week work well. Prolonged dieting without breaks increases metabolic adaptation and fatigue. Alternate deficit and maintenance for sustainable results.
Does a caloric deficit work for everyone?
Yes, it's a law of thermodynamics. But the rate of loss varies by individual (genetics, hormones, sleep, stress). If you don't lose weight despite a rigorous deficit for a month, consult a doctor to check your thyroid.
Can you eat anything as long as you're in a deficit?
For pure weight loss, yes—the deficit is king. But for health, energy, and muscle preservation, quality counts. 1,800 kcal of fast food will leave you hungry and tired. 1,800 kcal of whole foods will actually nourish you.

Similar guides

Calculate your optimal deficit

Find the deficit that works for you: effective, sustainable, and without muscle loss.

Go to the deficit calculator

Free · No commitment · 30 seconds