Why do I need to use のに instead of ので？


> 食べてばかりいるので、なんで太いじゃないだろう？？

I was told for this sentence I should use のに instead of ので. Why is のに better
here? It seems like it changes the meaning from “so/since” to “even though”.

I wanted to say “I’m just always eating so why aren’t I fat?” because I was
finding an example for してばかりいる (it was the first example that came to mind,
shhh!!!)




Because you are interpreting the English use of the word 'so' in your sentence
literally as 'consequently', you are equating that to **ので** , but the result
in your sentence doesn't follow the action/behavior. You can use **だから** in
this sense, but **ので** doesn't really work this way. It is more logical.

**ので** shows a natural or expected cause and effect behavior. _'I eat, so I
gain weight.'_.  
**のに** shows that the effect is not consistent with the cause. _'I eat, but I
don't gain weight?'_.

> A, therefore B (B logically follows from A) = **ので**  
>  A, and yet B (B does not logically follow from A) = **のに**

'I'm just always eating so why aren't I fat?' basically says the same thing as
'Even though I'm always eating, why don't I gain weight.' (The result of not
gaining weight is not consistent with the action of eating constantly).

Finally, 「なんで太いじゃない？？」is incorrect.  
「なんで太らないんだろう？？」would be best.  
An i-adjective + じゃない is like saying, 'It is ____, isn't it.' Remove the final
い and replace with く before adding ない (太くない). 太い is, however, used mainly for
objects and not people, with 細{ほそ}い being its antonym.  
When describing people, however, generally the present-progressive form is
used to indicate being overweight or underweight: 太{ふと}っている・太{ふと}っていない //
痩{や}せている・痩{や}せていない.  
For people (in the process of) gaining weight or losing weight the plain form
is used: 太{ふと}る・太{ふと}らない and 痩{や}せる・痩{や}せない.




Because you are interpreting the English use of the word 'so' in your sentence
literally as 'consequently', you are equating that to **ので** , but the result
in your sentence doesn't follow the action/behavior. You can use **だから** in
this sense, but **ので** doesn't really work this way. It is more logical.

**ので** shows a natural or expected cause and effect behavior. _'I eat, so I
gain weight.'_.  
**のに** shows that the effect is not consistent with the cause. _'I eat, but I
don't gain weight?'_.

> A, therefore B (B logically follows from A) = **ので**  
>  A, and yet B (B does not logically follow from A) = **のに**

'I'm just always eating so why aren't I fat?' basically says the same thing as
'Even though I'm always eating, why don't I gain weight.' (The result of not
gaining weight is not consistent with the action of eating constantly).

Finally, 「なんで太いじゃない？？」is incorrect.  
「なんで太らないんだろう？？」would be best.  
An i-adjective + じゃない is like saying, 'It is ____, isn't it.' Remove the final
い and replace with く before adding ない (太くない). 太い is, however, used mainly for
objects and not people, with 細{ほそ}い being its antonym.  
When describing people, however, generally the present-progressive form is
used to indicate being overweight or underweight: 太{ふと}っている・太{ふと}っていない //
痩{や}せている・痩{や}せていない.  
For people (in the process of) gaining weight or losing weight the plain form
is used: 太{ふと}る・太{ふと}らない and 痩{や}せる・痩{や}せない.

