Along with Jn 6, 1 Cor 11:29 is a locus classicus for the Real Presence. For people conditioned by that theological tradition, it may seem self-evident to them that 1 Cor 11:29 is referring to the "true body" of Jesus. To deny that is to disregard the plain sense of the text.
But that interpretation overlooks two things: (i) the actual context, and (ii) Paul's use of "body" as a metaphor for the church. For instance:
Stratified treatment put the lie not only to the Greek ideal of friends' equality, but for Paul challenged the significance of the Lord's supper. Table fellowship was a binding covenant, and the one bread and body represented not only Jesus's sacrifice but those who partook together (10:16-17; cf. 12:12). This failure to discern the corporate body (11:29) led to sickness in their individual bodies (11:30; cf. the individual and corporate bodies as temples in 3:16-17; 6:19). C. Keener, 1-2 Corinthians (Cambridge, 2005), 96.
The reference to participating in the Lord's supper in an unworthy manner must be understood in light of the context, where the Corinthians were practicing the supper in a way that humiliated other members of Christ's body. To eat and drink in an unworthy manner is to eat and drink in a way that demeans, humiliates, or disrespects other members of Christ's community.
To examine oneself means to examine one's compliance with the covenant as reflected in their ways of relating to other members of the community and to discern the body of Christ must include recognizing that those other members of the community represent Christ himself (since they have been united with him) and must be treated as people for whom Christ chose to give up his life and to shed his blood. R. Ciampa & B. Rosner, The First Letter to the Corinthians (Eerdmans, 2010), 554-55.
But what does the "body" mean here? Were the reference to the body of Christ under the species of bread, one would expect a parallel reference to the blood of Christ under the species of wine, particularly since Paul twice emphasizes "eating" and "drinking." Paul, therefore, does not make the criterion an ability to distinguish the eucharist from an ordinary meal.
The only alternative, since "body" alone is mentioned, is to take "body" as meaning the community. If Paul's conventions of writing were the same as ours, he would have written "Body" in order to indicate that he had in mind the Body of Christ. He presumed that his readers would remember what he had written in his allusion to the eucharist in the previous chapter "We who are many are one body, for we all partake of one bread" (10:17).
Before celebrating the eucharist, Paul wanted the assembled Christians to examine themselves on their relationships with one another. Were they only members of the Body of Christ sharing a common existence? Did they really being to one another? Or were they merely in the same space as others, without any bond or exchange of energy? These questions should still be in the mind of every believer who participates in the service of reconciliation that precedes the liturgy of the eucharist in our churches. J. Murphy-O'Connor, 1 Corinthians (Doubleday, 1998), 123.