How fast should I lose weight?

The NHMRC and most Australian health guidelines recommend losing 0.5-1.0 kg per week. Faster rates increase the risk of muscle loss, gallstones, and nutrient deficiencies. A rate of 0.5 kg per week (requiring a 500 kcal daily deficit) is sustainable for most people.

Why does the timeline account for slowing progress?

As you lose weight, your body becomes smaller and burns fewer kilojoules each day. This means the same calorie deficit produces less weight loss over time. Our calculator recalculates your TDEE at each projected week to give a realistic, not overly optimistic, timeline.

Is it harder to lose the last few kilograms?

Yes. As you get closer to your goal weight, your BMR and TDEE decrease, making the same deficit harder to maintain. Your body also tends to resist further fat loss through increased hunger hormones and reduced non-exercise activity. Patience and consistency are key during this phase.

What if I want to lose weight faster than 1 kg per week?

Losing more than 1 kg per week requires a large calorie deficit that is difficult to sustain and can lead to muscle loss, fatigue, and nutritional deficiencies. Very low calorie diets (VLCDs) of 1,800-3,400 kJ per day should only be followed under medical supervision.

Weight Loss Calculator

See exactly how long it will take to reach your goal weight with a personalised week-by-week projection. Enter your current stats and goal, and this calculator maps out your weight loss timeline with the daily calorie target needed.

Enter Your Details

Gender

Age

years

Current Weight

Height

Activity Level

Goal Weight

Weekly Loss Rate

How It Works

The calculator estimates your TDEE using the Mifflin-St Jeor equation, then applies your chosen weekly loss rate to determine the required daily deficit. Since 1 kg of body fat contains approximately 7,700 kcal (32,200 kJ), the daily deficit needed is (weekly loss in kg × 7,700) ÷ 7. The timeline accounts for decreasing TDEE as your weight drops by recalculating at each projected week.

Quick Reference

Weekly Rate	Daily Deficit	Time to Lose 5 kg	Time to Lose 10 kg	Time to Lose 20 kg
0.25 kg/wk	1,150 kJ (275 kcal)	20 weeks	40 weeks	80 weeks
0.5 kg/wk	2,300 kJ (550 kcal)	10 weeks	20 weeks	40 weeks
0.75 kg/wk	3,450 kJ (825 kcal)	7 weeks	14 weeks	27 weeks
1.0 kg/wk	4,600 kJ (1,100 kcal)	5 weeks	10 weeks	20 weeks

Approximate timelines assuming constant deficit. In practice, progress slows as weight decreases. This calculator accounts for that.

Frequently Asked Questions

How fast should I lose weight?: The NHMRC and most Australian health guidelines recommend losing 0.5-1.0 kg per week. Faster rates increase the risk of muscle loss, gallstones, and nutrient deficiencies. A rate of 0.5 kg per week (requiring a 500 kcal daily deficit) is sustainable for most people.
Why does the timeline account for slowing progress?: As you lose weight, your body becomes smaller and burns fewer kilojoules each day. This means the same calorie deficit produces less weight loss over time. Our calculator recalculates your TDEE at each projected week to give a realistic, not overly optimistic, timeline.
Is it harder to lose the last few kilograms?: Yes. As you get closer to your goal weight, your BMR and TDEE decrease, making the same deficit harder to maintain. Your body also tends to resist further fat loss through increased hunger hormones and reduced non-exercise activity. Patience and consistency are key during this phase.
What if I want to lose weight faster than 1 kg per week?: Losing more than 1 kg per week requires a large calorie deficit that is difficult to sustain and can lead to muscle loss, fatigue, and nutritional deficiencies. Very low calorie diets (VLCDs) of 1,800-3,400 kJ per day should only be followed under medical supervision.

How This Is Calculated

Daily Deficit (kcal) = (Weekly Loss Rate × 7,700) ÷ 7 Target Intake = TDEE − Daily Deficit Weeks to Goal = Total Loss ÷ Weekly Loss Rate Note: TDEE is recalculated each week as weight drops

7,700: = Approximate kcal per kg of body fat
TDEE: = Total Daily Energy Expenditure, recalculated weekly
Weekly Loss Rate: = Chosen rate: 0.25, 0.5, 0.75, or 1.0 kg/week

The projection recalculates your TDEE each week as your weight drops, providing a more realistic timeline than simple linear projections.

Related Tools

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.

TDEE Calculator

Calculate your Total Daily Energy Expenditure using the Mifflin-St Jeor equation. See how many calories and kilojoules you burn per day.

kJ Per Day to Lose Weight Calculator

Calculate how many kilojoules per day you should eat to lose weight at a safe, sustainable rate.

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.