Some are questioning whether a Mexican man really did spend more than a year lost at sea.

Real Life Cast Away? Man Says He Survived Over a Year at Sea!

Jose Salvador Alvarenga set out on a shark fishing trip off the Pacific coast of Mexico in Dec. 2012, but his boat broke down. He then claims to have drifted 8,000 miles to the Marshall Islands, southwest of Hawaii.

A man who was along with him died months before, he said.

Alvarenga says he survived by drinking rainwater, as well as his own urine, and eating raw fish, birds and turtles. health editor Dr. Manny Alvarez sat down with Martha MacCallum this morning to give us his take. In short, he's not buying the man's version of events.

Saying he finds the story "impossible" to believe from what he has read, Alvarez noted that he has seen people that looked far worse than Alvarenga after only two or three weeks adrift at sea.

"You can't drink your urine, that's impossible because he would have been dead within weeks. All the things that are in urine would be highly toxic," he explained, adding that from a doctor's point of view "this is not a person who has been drifting for over a year in the ocean."

"I'll be the first one to apologize to Jose [if the story is true]," said Alvarez.

Check out the full discussion above.