This comes from a study by retired flag officers and can be read in full @ http://cdn.missionreadiness.org/NATEE1109.pdf
Now, with that out of the way, I find the author of this piece somewhat biased. He tried to get into OCS and was turned down due to medical reasons. He then tried the Navy and quit when he was turned down by the Army National Guard.
He claims a retired military physician gave him a letter saying he was fit to serve.
This is the conundrum of recruitment. One might be fit to perform selected duties, but that does not mean they are physically capable of performing the most basic reason for being in the military – conducting war with a pistol or rifle in hand.
According to AMSARA, the top conditions for active duty medical disqualification from 2010-2014 were weight/body build (17 percent), psychiatric (12 percent), refraction (11 percent), and skin/allergies (9 percent). These conditions largely hold across years and components. Many conditions included in these categories may inhibit an applicant’s ability to serve effectively. However, many do not. Although overweight applicants would most likely not be able to meet military physical standards, according to AMSARA one-third of “weight/body build” disqualifications include cases of underweight applicants who may not have such issues. Ongoing psychiatric conditions should be taken seriously, but even symptoms or outpatient treatment of depression within three years of applying for military service is disqualifying, according to the Department of Defense’s Medical Standards for Appointment, Enlistment, or Induction regulations. Vision that cannot be corrected to 20/40 as well as allergic reactions to fish, insects, and nuts can be disqualifying as well.
Much more of this piece @ Department of Disqualified: Fixing the Broken Military Medical Accessions Process w/lots and lots of links.