How many kJ per day to lose 1 kg per week?

To lose 1 kg per week, you need a daily deficit of approximately 4,600 kJ (1,100 kcal) below your maintenance level. For most people, this means eating around 5,000-6,500 kJ per day, depending on activity level. Note: losing more than 0.5-1 kg per week is generally not recommended.

How many kilojoules per day to lose weight for a woman?

Most women can lose weight eating 5,000-6,500 kJ per day, depending on their size and activity level. It's generally not recommended to go below 5,000 kJ (1,200 kcal) per day without medical supervision.

Is 5000 kJ a day enough?

5,000 kJ (about 1,200 calories) is a low but manageable intake for many women aiming for weight loss. For men, this is typically too low. The minimum safe intake depends on your body size and should be discussed with a healthcare provider.

How many kilojoules per day to lose 1 kg per week?

You need a daily kJ deficit of approximately 4,600 kJ below maintenance. If your maintenance is 8,700 kJ, you'd need to eat about 4,100 kJ per day - which is quite restrictive. A more sustainable approach is losing 0.5 kg per week (deficit of ~2,300 kJ/day).

kJ Per Day to Lose Weight Calculator

Find out exactly how many kilojoules you should eat per day to reach your weight loss goal. Enter your details and desired rate of weight loss, and this calculator will give you a daily kJ target.

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How It Works

First, your maintenance energy is calculated using the Harris-Benedict formula. Then, a deficit is applied based on your target weekly weight loss. One kilogram of body fat contains approximately 32,200 kJ (7,700 kcal). To lose 0.5 kg per week, you need a daily deficit of about 2,300 kJ.

Quick Reference

Goal	Daily Deficit (kJ)	Weekly Deficit (kJ)
0.25 kg/week	1,150	8,054
0.50 kg/week	2,300	16,109
0.75 kg/week	3,450	24,163
1.00 kg/week	4,600	32,217

1 kg of body fat ≈ 32,217 kJ (7,700 kcal) of stored energy.

Frequently Asked Questions

How many kJ per day to lose 1 kg per week?: To lose 1 kg per week, you need a daily deficit of approximately 4,600 kJ (1,100 kcal) below your maintenance level. For most people, this means eating around 5,000-6,500 kJ per day, depending on activity level. Note: losing more than 0.5-1 kg per week is generally not recommended.
How many kilojoules per day to lose weight for a woman?: Most women can lose weight eating 5,000-6,500 kJ per day, depending on their size and activity level. It's generally not recommended to go below 5,000 kJ (1,200 kcal) per day without medical supervision.
Is 5000 kJ a day enough?: 5,000 kJ (about 1,200 calories) is a low but manageable intake for many women aiming for weight loss. For men, this is typically too low. The minimum safe intake depends on your body size and should be discussed with a healthcare provider.
How many kilojoules per day to lose 1 kg per week?: You need a daily kJ deficit of approximately 4,600 kJ below maintenance. If your maintenance is 8,700 kJ, you'd need to eat about 4,100 kJ per day - which is quite restrictive. A more sustainable approach is losing 0.5 kg per week (deficit of ~2,300 kJ/day).

How This Is Calculated

Daily deficit (kJ) = (target weekly loss in kg × 32,217) ÷ 7 Target intake (kJ) = maintenance kJ − daily deficit

32,217 kJ: = energy stored in 1 kg of body fat (7,700 kcal × 4.184)
maintenance kJ: = your TDEE (BMR × activity multiplier)

This is a simplified energy balance model. Actual weight loss depends on metabolic adaptation, water retention, and body composition changes.

Related Tools

Maintenance kJ Calculator

Calculate how many kilojoules you need per day to maintain your current weight based on your body stats and activity level.

Kilojoule Deficit Calculator

Calculate your daily kilojoule deficit and see how it translates to weekly weight loss. Plan your energy balance.

Calorie Deficit Calculator

Calculate your optimal calorie deficit for weight loss. See how long it will take to reach your goal weight with a safe, sustainable deficit.

Disclaimer

This calculator provides estimates for informational purposes only and should not be considered medical advice. Individual results may vary based on factors not captured by these formulas. Consult a healthcare professional before making changes to your diet or exercise routine, especially if you have any existing health conditions.