中なの

currently ...ing

→ 中
phrase Uncommon #12,090
currently ...ing Used after a noun or activity stem to say that someone is currently doing something or is in the middle of something. The ending なの adds an explanatory tone and is informal.
JA: 今、勉強中なの。
EN: I'm studying right now.

料理中なの

I'm cooking, you know?

— ブエノスアイレス (1997)

減量中なの

Are you trying to lose weight?

まだトム電話中なの

Is Tom still on the phone?

トムダイエット中なの

Is Tom on a diet?

トムはまだダイエット中なの

Is Tom still on a diet?

トムはまだ休暇中なの

Is Tom still on vacation?

誰がダイエット中なの

Who’s on a diet?

ここだけの話だけどあの太った醜い男は減量中なの

Just between you and me, that fat, ugly man is trying to lose weight.

phrase Uncommon #12,732
currently ...ing 中 indicates that someone is currently in the middle of an activity or state. The ending なの adds an explanatory tone; related forms include 中なんだ and 中なんです.
JA: 今、会議中なの。
EN: I'm currently in a meeting.

有給休暇中なの

I’m on paid leave right now.

ダイエット中なの

I'm on a diet right now.

ここだけの話だけどあの太った見苦しい魔女ダイエット中なの

Between you and me, that fat, unappealing witch is on a diet.

あたし禁煙中なの

I'm trying to quit smoking.

— フィフス・エレメント (1997)

お休み中なの

I'm on a break right now.

— 魔女の宅急便 (1989)

彼は今お食事中なの

Is he eating right now?

— フォーリング・ダウン (1993)

料理中なの

I'm cooking right now.