The ADF was targeting too many recruits straight from school who were physically unfit and did not have the resilience or life experience to cope, with "absolutely soul destroying" consequences.
The national president of The Royal Australian Regiment Corporation, Michael von Berg, told the Royal Commission into Defence and Veteran Suicide young recruits in their first year of training had the highest level of suicide rates in the defence services.
"A lot of these young people come from disadvantaged homes," Mr von Berg said.
"They are trying to find a new family, they are trying to find a new life... and they fail.
"They are just individuals who were not suitable (for service) in the first place... It is absolutely soul destroying."
Mr Von Berg's call for a change to ADF recruitment practices was backed by a panel of veteran support organisations giving evidence to the commission on Friday.
National president of the Defence Reserves Association, Major General Paul Irving (Ret'd) said young recruits had "little life experience... and did not appear as resilient as earlier generations".
Defence, he said, had also reduced physical entry standards.
"To get into the ADF at the moment you only have to do four push ups," he said.
The commission was told poor leadership in defence was also a major problem, resulting in young lives being "shattered" by punishing training programs they were not physically capable of doing.
The national president of the Totally and Permanently Incapacitated Ex Servicemen and Women Federation of Australia, Pat McCabe, said she was aware of one young man "who was 19 when he joined and at 21 he was broken, just from recruit training".
"He didn't have the body build to be in infantry and this is what caused his injuries," she said.
"Now, at 24, he's TPI (totally and permanently incapacitated). That's his life gone."
Ms McCabe said the way the army rehabilitation unit had treated him after his injuries had also triggered several suicide attempts.
"This young bloke was told that after having operations on his feet... he had to sweep the storeroom. When he said, 'I have just been operated on', they said, 'You're wearing the King's uniform around earning the King's shilling, so you will do the job'."
She said once the young man had been declared unfit for the infantry the army refused his request to be transferred to the linguistics corps, despite the fact he "was an untrained expert in languages, he was amazing".
Instead, he was forced into a medical discharge.
"The rehabilitation... destroyed his mental health because of what they put him through.
"This young man joined the army full of dreams and two years later he was a shattered man."
The commission also heard at the other end of the spectrum Vietnam veterans were also being denied their Gold Card veteran's entitlements for critical health care services like pharmaceuticals and hearing aids.
Ms McCabe said many Vietnam veterans had suicided because the health services for veterans were so overwhelmed, many of them "just give up".
"The Vietnam vets are getting older and sicker and they are tired of fighting the system," Ms McCabe said.
"They have been fighting the system ever since they got home from Vietnam and it's just one fight after another. Why does a veteran have to fight the government? It's just wrong."
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Australian Associated Press