When a Jewish person becomes a follower of Yeshua, he does not cease being a Jew. That person may still feel called or choose for cultural reasons to still keep the Torah in a fashion they are comfortable with.
Scripture tells us that Yeshua said that he did not come to do away with the Law, but to fulfil it (see Matthew 5:17-19). James and the elders of the congregation in Jerusalem told the apostle Paul that tens of thousands of Jewish people had believed in Yeshua and were zealously keeping the Law (Acts 21:20). Thus, the early Jewish believers (some 30 years after Yeshua's death and resurrection) were still keeping the Law.
Today, there is a range of views amongst all believers on this issue. There is a lack of census as to who should keep what and why and how. Clearly, Scripture does not condemn Jewish believers who follow Yeshua as their Lord from following the Torah, neither should other believers.
This said, there are some who suggest such practices are matters that determine one's salvation. This is not view that is acceptable for a follower of Yeshua.