In Australia, legally you're homeless if you have no permanent place of residence, and no prospect of one. So if you're staying in a cheap backpacker's then you're homeless.
Back in 1999 I was homeless for a while. First I was in backpacker's while I looked for work, then my money ran out, I spent two days on the street before I swallowed my pride and applied at a homeless shelter. They have limited places and each night they assess people by need, so the elderly or mentally ill went before me, I remained on the street another five nights until some friends took me in.
During that week on the street I was actually working, however it was temp work and they paid a fortnight in arrears. I showered etc at the workplace each day.
I was lucky in that as I was a chef, I could eat at work. The actual canteen cost money, but nobody cared if you ate stuff in the kitchen where you worked.
I stayed with friends for a few weeks until I'd saved enough money to get into a share flat.
Many people are homeless for a short time in their lives, but like me they have friends and family to take them in, and have some social and work skills to help them get a job and thus an income. The long-term homeless tend to be those who are mentally ill, have a criminal record (and thus find it difficult to get work), have a substance abuse problem, two of those, or even all three.
On the street I saw lots of mentally ill people, lots of addicts, and lots of people with criminal convictions. These people are the rubbish of society - meaning that we throw them away and try not to think of them again. Australia has fairly good resources available for the unemployed, single parents and so on, but is pretty shit when it comes to the mentally ill, addicts and those with records.
Australia's fast food is not subsidised as heavily as that in the US, however it's still pretty cheap, and if you don't have a kitchen you have no alternative, you can't subsist on raw vegetables and meat. As well, remember that if you're homeless it's because you have nowhere to go. You're on the street and nobody cares.
Just think about that for a moment. Think of all the people you love, all your family and friends, your parents, siblings, all the people you went to school with and kept in touch with, former workmates. You contact them all and they all turn you away.
This doesn't exactly lift your spirits, and fast food, alcohol, tobacco and drugs start to look pretty attractive. In my week on the street I was offered free heroin, luckily I don't like needles. I was also offered a lot of violence, between mental illness and the desperation of substance addiction and poverty, people get nasty.
If the homeless are fatties, I say good on them. At least they have something pleasant in their lives.