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Calorie deficit calculator

Find the calorie deficit you need to reach your weight goal. A realistic plan with a timeline and safety alerts.

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What is a calorie deficit?

A calorie deficit means eating fewer calories than your body burns. It's the fundamental principle of weight loss, regardless of the diet you follow. When you're in a deficit, your body taps into its energy reserves (body fat) to make up the difference. A deficit of 7700 kcal corresponds to roughly one kilogram of fat lost. The goal is to find the right balance: enough deficit to make progress, but not so much that you compromise your health and muscle mass.

What calorie deficit for weight loss?

A deficit of 300 to 500 kcal per day is generally recommended for healthy, sustainable weight loss — about 0.3 to 0.5 kg per week. A deficit greater than 1000 kcal per day is considered aggressive and can lead to muscle loss, a slower metabolism, nutritional deficiencies and the yo-yo effect. Medical guidelines suggest not exceeding 1% of body weight per week in loss.

Why extreme deficits backfire

Drastically cutting calories (e.g. going from 2500 to 1200 kcal) triggers metabolic adaptation: your body reduces energy expenditure to compensate. The result: weight loss slows, fatigue sets in, and as soon as you return to normal eating, weight often comes back past the starting point. A moderate deficit (15-25% of TDEE) is far more effective long term and preserves muscle mass.

How to maintain a calorie deficit day to day

The key is tracking. Without measuring your intake, you don't know if you're actually in a deficit. Kalo makes tracking easy: send your meals via WhatsApp message and Kalo automatically calculates your calories and macros. You get a daily summary showing exactly where you stand against your goal. No complicated app, no obsessive food weighing.

Frequently asked questions

How long to lose 5 kg?
With a healthy 500 kcal/day deficit, you can lose about 0.5 kg per week. So losing 5 kg would take about 10 weeks. This pace preserves your muscle mass and avoids the yo-yo effect.
Is a 1000 kcal per day deficit dangerous?
A 1000 kcal/day deficit is very aggressive for most people. It can cause fatigue, muscle loss, deficiencies and a slower metabolism. A 300-500 kcal deficit is healthier and more sustainable. Consult a healthcare professional before considering a large deficit.
Do you need to be in a deficit every day?
What matters is your average deficit over the week. You can have days at maintenance (weekends, social events) and offset them with days in a deeper deficit. The important thing is that your weekly average matches your goal.
Does a calorie deficit cause muscle loss?
A moderate deficit combined with sufficient protein intake (1.6-2g/kg) and strength training preserves muscle mass. An overly aggressive deficit or insufficient protein, on the other hand, drives muscle loss.
How do I know if my deficit is too large?
Signs of an overly aggressive deficit include: chronic fatigue, irritability, loss of strength, sleep issues, constant hunger and stalled weight despite low intake. If you feel these symptoms, increase your calories by 200-300 kcal.

Take action with Kalo

Now you know your needs. Send your meals on WhatsApp and Kalo tracks everything automatically for you.

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