Why fast weight loss doesn't work (and what does)

“How to lose weight fast” is one of the most common questions online. We understand why you want it to be quick. But the honest answer is this: the fast way usually doesn't last. Here's why, and what works instead.

Information checked on 2026-09-26. General information, not medical advice. How we calculate

In short: a safe pace is about 0.5 kg a week. It's slower, but it's easier to keep up, and the weight you lose is more likely to stay off.

The first-week miracle is water

Your body stores some of its energy in your muscles and liver as glycogen, and glycogen holds on to water. When you eat less, especially fewer carbohydrates, your glycogen stores shrink, and the water goes with them. That's why in the first few days the scales can show several kilos less, even though you've lost far less fat.

This is where promises like “lose 5 kg in a week” come from. When you go back to eating normally, the water comes back, and it feels as if it was all for nothing. It wasn't. It just wasn't fat.

What very strict diets do

Very low-calorie diets (for example, a few hundred calories a day) without a doctor's supervision can:

  • reduce your muscle mass, not just fat, especially if you're short on protein;
  • cause tiredness, dizziness, irritability and difficulty concentrating;
  • increase the risk of gallstones, a known risk with very fast weight loss;
  • cause a rebound effect: when the strict diet ends, the hunger and the old habits come back, and the weight often comes back with them.

Research shows that the body adapts to eating less: you get hungrier, and you use slightly less energy. So the stricter the diet, the harder it is to stick to for long.

What pace is safe

The most commonly recommended pace is no faster than about 0.5 kg a week, and slower is perfectly fine too. A small calorie deficit is usually all it takes. Dumpli never plans below your basal metabolic rate (BMR), and never below 1,200 kcal for women or 1,500 kcal for men, whichever number is higher. You can check your numbers in the calorie calculator.

Plateaus are normal

Your weight goes up and down every day because of water, salt, what's in your gut, sleep and hormones. Sometimes it doesn't move for a week or two, and then it suddenly drops. That isn't failure. Look at the trend over several weeks, and remember that the scales aren't the only measure: how your clothes fit, your energy and your sleep matter too.

What really works

  • A small deficit. A little less than you use, but not starving yourself.
  • Protein at every meal. It keeps you full for longer and helps you keep your muscle. For example, eggs, curd cheese (quark), yoghurt, fish, poultry and pulses.
  • Fibre. Vegetables, fruit, wholegrain foods and pulses keep you full for fewer calories.
  • Sleep. When you're short on sleep, you crave sweet and fatty food more. Try to get enough sleep, and go to bed at a similar time.
  • Walking. You don't need to go straight to the gym. A 15-minute walk after a meal, the stairs instead of the lift or getting off one stop early is a good place to start.
  • Consistency, not perfection. One pizza night doesn't ruin anything. What matters is what happens on most days.

When to talk to a doctor first

Before you change how you eat to lose weight, talk to your doctor first if:

  • you are pregnant or breastfeeding;
  • you have diabetes or take medicines that affect your blood sugar;
  • you have kidney disease, heart disease or another long-term condition;
  • you are under 18;
  • you have or have had an eating disorder;
  • you are losing weight without trying.

If your relationship with food worries you, you can talk to a doctor or a psychologist. If you're struggling right now, call your local emergency number or find a free helpline at findahelpline.com.

Slowly, but filling. The Dumpli nutrition quiz suggests a safe calorie target and a filling plan, and in sensitive situations it sends you to a doctor first. Take the free nutrition quiz →

Frequently asked questions

Why does weight drop quickly in the first week and then slow down?

In the first few days of eating less, especially fewer carbohydrates, your body uses up its glycogen stores, and loses water along with them. So the first drop is mostly water, not fat. After that, weight comes off more slowly, and that's normal.

How many kilos a week is it safe to lose?

The most commonly recommended pace is no faster than about 0.5 kg a week, and slower is perfectly fine too. A faster pace should only happen under a doctor's supervision.

My weight hasn't moved for two weeks. What should I do?

Plateaus are normal: your weight changes every day with water, salt, what's in your gut and hormonal ups and downs. Look at the trend over several weeks, not at a single day. If your weight hasn't moved for more than a month, look again at your portions and how much you move, but don't cut calories below the safe limit.

Can you lose weight without exercise?

Yes – your weight depends mostly on what you eat. But movement helps you keep your muscle and improves your mood and sleep. Even a 15-minute walk or taking the stairs instead of the lift is a good place to start.

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