I think this question is not well-defined. 

The Jews in Israel needed to follow the law as interpreted by the Pharisees because they sat in Moses' seat (Matthew 23:2) and so to disobey would be to sin. 

Some new Gentile converts were given other laws at the apostolic council in Acts, as you cite. 

Elsewhere Paul gave different rules to the Corinthians (1 Cor 10.15-22), leaving the eating of meat presented to idols up to the believer's conscience. 

Each of us has to be accountable to someone else, but we are not all accountable to the same person, nor are we all charged with the same rules to follow. It is sin if we break those rules, though, even if there is nothing inherently sinful about any type of food. The sin comes from breaking the law, not from eating the animal.