Translation guide
How to express losing weight in Japanese, from general weight loss to dieting and slimming down.
I want to lose weight.
To say that someone has lost weight, or that weight has decreased, in a neutral or factual way.
The most common and neutral way to say 'lose weight' (literally 'body weight decreases'). Use this for factual statements.
I've lost weight recently.
I lost weight after exercising.
Means 'to become thin/slim'. Often implies a visible change in appearance, not just a number on the scale. Can be used for people or body parts.
Similar to 体重が減る but slightly more casual/conversational. '落ちる' means 'to drop/fall'.
To talk about actively trying to lose weight, being on a diet, or succeeding in losing weight through effort.
The most common way to say 'to go on a diet' or 'to try to lose weight'. It implies intentional effort. Note: ダイエット in Japanese often means weight-loss diet, not just general eating habits.
To express that someone looks slimmer, or to talk about losing weight for aesthetic reasons, often targeting specific areas.
Means 'to become slim'. Focuses on the resulting slender appearance. Often used in fashion/beauty contexts.
To describe weight loss that is not on purpose, often with a negative connotation.
痩せる with 〜てしまう adds a nuance of something happening unintentionally or regrettably.
Do not translate 'lose weight' literally as 体重を失う (たいじゅうをうしなう). It sounds unnatural and is not used.
痩せる focuses on becoming thin/slim in appearance, while 体重が減る is purely about the number on the scale. You can 体重が減る without looking 痩せた, and vice versa.
In Japanese, ダイエット usually implies a weight-loss diet. If you mean a diet as in general eating habits, use 食生活 (しょくせいかつ) or 食事 (しょくじ).
She lost a lot of weight.
彼女は痩せたね。
She's lost weight, hasn't she?
My face has gotten thinner.
I lost weight due to summer fatigue.
I'm on a diet right now.
I succeeded in losing weight.
Literally 'try to become thin'. Emphasizes the effort or intention.
I'm trying to lose weight, but it's quite difficult.
A more formal or technical term for 'weight reduction'. Often used in sports, health contexts, or written language.
Boxers lose weight before a match.
You look slimmer in this dress.
From English 'shape up'. Implies toning and losing weight through exercise.
I want to shape up by summer.
Means 'to tighten/firm up'. Used for specific body parts (e.g., stomach, arms). Not general weight loss.
Exercises to tighten the stomach.
I lost weight because of illness (and it's unfortunate).
Onomatopoeic word meaning to become haggard or lose a lot of weight drastically, often from exhaustion or illness.
He lost a lot of weight and looked haggard after being hospitalized.
I need to lose weight for health reasons.