Dick vs. mollig vs. fett
The German words dick, mollig, and fett all describe a person who carries excess body fat, but they differ significantly in their tone, emotional weight, and level of politeness. Choosing the correct word is crucial to accurately convey your message and avoid unintentionally offending someone.
Dick
The word dick is the most common and standard translation for fat or overweight. While it serves as a general, factual description of someone's size, calling a person dick directly to their face is usually considered blunt and can easily hurt their feelings.
Der Arzt sagte ihr streng, dass sie zu dick sei und mehr Sport machen müsse.
(The doctor told her strictly that she was too overweight and needed to exercise more.)
Ich fühle mich heute in diesem Kleid wirklich dick.
(I feel really fat in this dress today.)
Viele Menschen werden im Alter ein bisschen dick.
(Many people get a little fat in old age.)
Mollig
The word mollig translates to plump, chubby, or curvy. It is a much softer, more polite, and often affectionate euphemism used to describe someone who is pleasantly rounded without sounding harsh or critical.
Sie ist eine mollige Frau mit einem wunderschönen Lächeln.
(She is a plump woman with a beautiful smile.)
Das Baby hat unglaublich süße, mollige Wangen.
(The baby has incredibly sweet, chubby cheeks.)
Er hat mir verraten, dass er mollige Frauen lieber mag als sehr dünne.
(He revealed to me that he prefers curvy women over very thin ones.)
In der Werbung sieht man heutzutage glücklicherweise auch mollige Models.
(Fortunately, you also see chubby models in advertising nowadays.)
Fett
The word fett means fat or obese and is highly derogatory and insulting when applied to people. While it is a completely normal word for describing greasy food or large animals, applying fett to a person implies a lack of respect and is generally used as a harsh insult or to describe severe obesity.
Der wütende Mann nannte den Fahrer einen fetten Idioten.
(The angry man called the driver a fat idiot.)
Es ist extrem unhöflich, jemanden auf der Straße einfach als fett zu bezeichnen.
(It is extremely rude to simply label someone on the street as obese.)
Er wurde in der Schule leider oft gemobbt, weil er fett war.
(Unfortunately, he was often bullied at school because he was fat.)
Ich habe in den Ferien so ungesund gegessen, dass ich das Gefühl habe, richtig fett zu werden.
(I ate so unhealthily during the holidays that I feel like I am getting really fat.)
Summary
In summary, use dick as the standard but direct word for being overweight, choose mollig when you want to be polite and describe someone as pleasantly plump or chubby, and completely avoid using fett for people unless you are speaking medically about severe obesity or intend to be highly insulting.