How to calculate your calorie deficit

Losing weight comes down to a simple equation: burning more calories than you consume. But putting it into practice is more nuanced. A deficit that is too small won't show visible results; a deficit that is too aggressive triggers survival 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 rebound. Avoid deficits higher than 750 kcal.

3

Calculate your daily calorie goal

TDEE minus your chosen deficit. Example: 2,400 - 500 = 1,900 kcal/day. Ensure this number stays above your BMR (Basal Metabolic Rate). If it doesn't, reduce the deficit — eating below your BMR slows your metabolism and promotes 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). Choose foods with high nutrient density and low calorie density: 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 stalls for more than 3 weeks, reduce by 100-150 kcal or add an activity session. Plateaus are normal — don't panic.

The science of calorie 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 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 maximum loss of 0.5 to 1 kg per week. Faster than that, you lose muscle, not just fat. People with a very high starting weight (BMI > 35) can handle a larger deficit initially, but most people should aim for a 400-600 kcal deficit. For athletes, a 300-400 kcal deficit is preferable to maintain performance and recovery.

Plateaus and how to overcome them

A plateau is a weight stall lasting 3 weeks or more despite a maintained deficit. Possible causes: metabolic adaptation, water retention (especially for women during their cycle), underestimating portions, or overestimating exercise. Solutions: a week at maintenance calories (a 'diet break') can reset the metabolism. Reducing sodium slightly decreases water retention. Checking portions with a food scale often reveals hidden calorie gaps.

FoodCraft Tip

Personalized deficit calculator

The FoodCraft calorie deficit calculator computes 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 calories

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

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Frequently asked questions

Is a 1,000 kcal deficit dangerous?
It is excessive for most people. Such an aggressive deficit leads to significant muscle loss, constant fatigue, uncontrollable cravings, and often a yo-yo effect. Only people with severe obesity under medical supervision should attempt such a deficit temporarily.
Should I create the deficit through diet or exercise?
Ideally both, but diet is more efficient. Running for 30 minutes burns about 300 kcal — the same as a croissant. It's easier to just not eat the croissant. However, exercise is essential for preserving muscle mass during a deficit.
How long should I maintain a deficit?
Phases of 8-12 weeks followed by a week of maintenance work well. Prolonged dieting without breaks increases metabolic adaptation and fatigue. Alternate between deficit and maintenance for sustainable results.
Does a calorie 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, see a doctor to check your thyroid.
Can I eat anything as long as I'm in a deficit?
For pure weight loss, yes — 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.

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