Key takeaways
- A sensible rate of loss is about 0.5 to 1 percent of your body weight a week.
- Heavier people can lose a little faster. Leaner people should go slower.
- Losing faster than this raises the risk of muscle loss, fatigue and regain.
- Judge your rate from weekly averages over at least three weeks, not single weigh-ins.
- A pace you can keep until the end beats a pace that looks good for a fortnight.
How fast should you lose weight? For most people, about 0.5 to 1 percent of body weight a week is the right pace. That is roughly 0.4 to 0.8 kg a week at 80 kg. It is quick enough to see progress and slow enough to keep your muscle, your energy and your routine. The first week or two often looks faster because of water.
How fast should you lose weight each week?
Aim to lose about 0.5 to 1 percent of your current body weight each week. Using a percentage instead of a fixed number keeps the target fair for different body sizes, and it adjusts itself as you get lighter.
| Current weight | 0.5 percent a week | 1 percent a week |
|---|---|---|
| 60 kg (9 st 6 lb) | 0.3 kg | 0.6 kg |
| 70 kg (11 st) | 0.35 kg | 0.7 kg |
| 80 kg (12 st 8 lb) | 0.4 kg | 0.8 kg |
| 90 kg (14 st 2 lb) | 0.45 kg | 0.9 kg |
| 100 kg (15 st 10 lb) | 0.5 kg | 1.0 kg |
| 120 kg (18 st 13 lb) | 0.6 kg | 1.2 kg |
Where you sit in that range depends on how much you have to lose:
- More body fat to lose: the upper end is usually comfortable and appropriate.
- Already fairly lean: stay near the lower end. There is less fat to draw on, so the risk to muscle and training is higher.
- Busy, stressful period: choose the lower end so the plan survives a hard week.
For most people this pace comes from a moderate deficit of roughly 300 to 500 kcal a day. The calorie and protein calculator will give you a starting target, and calorie deficit explained shows how to adjust it.
If you are pregnant, breastfeeding, under 18, living with a medical condition, taking medication that affects appetite or weight, or have a history of disordered eating, speak to your GP or doctor before trying to lose weight.
Why is losing weight too fast a problem?
Losing weight too fast is a problem because a larger share of what you lose is muscle and water, and because the diet becomes very hard to continue. The number on the scale drops, but the result is worse and it rarely lasts.
What tends to happen with an aggressive deficit:
- Muscle loss. With too little energy coming in, your body is less able to hold on to muscle, even if you train.
- Poor training. Strength and stamina fall, so sessions become less productive.
- Rising hunger and low mood. Food starts to occupy your thoughts and social meals become stressful.
- Less daily movement. You sit more and fidget less, which narrows the deficit you are working so hard to create.
- Rebound. Strict phases are often followed by overeating, and the cycle repeats.
There is also a practical cost. A very fast diet teaches you nothing about how to eat at your new weight. The guide to how to lose weight without a crash diet explains the alternative.
Why do you lose weight faster in the first week?
You lose weight faster in the first week because much of the early drop is water, not fat. When you eat less, particularly less carbohydrate and salt, your body holds less water and has less food in the digestive system.
That is why someone can lose 2 kg in week one and 0.5 kg in week two without having done anything wrong. Week two is closer to the real rate.
For the same reason, ignore the first fortnight when working out your true rate. Use the weekly averages from week three onwards.
Can you lose weight too slowly?
Yes. If your weekly average is falling by much less than 0.5 percent of your body weight, the deficit is very small and easily wiped out by one untracked meal. Progress becomes hard to see, and motivation fades.
Slow is not automatically wrong. A slower pace suits you if:
- you are already lean and want to keep muscle and gym performance
- you are aiming for body recomposition, where fat loss and muscle gain happen together
- you are in a demanding period at work or home and need a lighter plan
But if you have a meaningful amount to lose and the scale has barely moved in a month, tighten things up. Check your tracking first, then your steps, then consider a small calorie reduction.
How do you check your rate of weight loss?
Check your rate by comparing weekly averages, not individual days. Daily weight moves up and down with water, salt, hormones and digestion, and reacting to each reading leads to poor decisions.
- Weigh in the morning, after the toilet and before eating or drinking, at least three or four days a week.
- Work out the average for each week.
- Subtract this week's average from last week's to get your weekly change.
- Divide by your body weight and multiply by 100 to get the percentage.
- Review over three weeks before changing anything.
For example, if your average goes from 86.0 kg to 85.4 kg, you have lost 0.6 kg. That is about 0.7 percent, which is right in the target range.
Then act on what you see:
- Within the range: change nothing.
- Faster than 1 percent after the first two weeks: add a little food, especially if energy or training is suffering.
- No change for three weeks: work through the steps in the guide to breaking a weight loss plateau.
How long will it take to reach your goal weight?
You can estimate it by dividing the amount you want to lose by your expected weekly rate, then adding time for breaks. Treat the answer as a rough guide, not a deadline.
Someone at 90 kg aiming for 80 kg might average 0.5 to 0.7 kg a week. That suggests roughly 14 to 20 weeks of dieting. In reality there will be holidays, celebrations, busy periods and the odd flat week, so the calendar time is usually longer. Individual results vary.
Three things make the longer view easier:
- Work in phases. A block of dieting followed by a period at maintenance is more sustainable than one long push. JR Coaching structures progress this way, with each phase having a clear purpose.
- Set process goals. Hit your calories, protein, steps and sessions this week. The outcome follows.
- Plan for maintenance. Reaching the number is half the job. See how to maintain weight after a diet.
You can see how this looks in practice on the weight loss programme page and on the client results page.
Frequently asked questions
Is losing 1 kg a week healthy?
For someone weighing around 100 kg or more, 1 kg a week is about 1 percent of body weight and is a reasonable upper limit. For a 60 kg person it is too fast and would need a very large deficit. Scale the target to your size instead of using one figure for everyone.
How much weight can you lose in 12 weeks?
At 0.5 to 1 percent of body weight a week, most people would expect to lose roughly 5 to 10 percent of their starting weight over 12 weeks, assuming consistent adherence. For an 85 kg person that is about 4 to 8.5 kg. Individual results vary, and the first couple of weeks include some water.
Should you lose weight faster for a holiday or event?
A slightly firmer deficit for a few weeks is fine if you are otherwise healthy and keep protein and training in place. Avoid drastic cuts. They mostly remove water, leave you tired for the event and tend to be followed by rapid regain. Starting earlier at a moderate pace gives a better and more lasting result.
The bottom line
Aim for about 0.5 to 1 percent of your body weight a week, judge it from weekly averages and adjust in small steps. Faster is rarely better. Steady is what gets you to the end with your muscle and your sanity intact. Forward, every week. If you want your pace set and reviewed for you, apply for coaching and JR will reply personally.
This guide is general information for healthy adults and is not medical advice. If you have a health condition, are pregnant or take medication, speak to your GP before changing your training or diet. Results vary from person to person.
