The bottom 20 per cent of the New Zealand population has not been able to respond to the recent spate of price rises by increasing the proportion of their income - or the time required to earn that income - on providing healthy food for themselves and their families.
Tight budgets seem to be biting for this group.
Eating healthily is even more difficult for families where parents work long hours but still don't earn much. About 90,000 people (4 per cent of workers) work 50 hours a week but still take home less than $30,000 - far less than the average wage.
In fact, almost 14,000 people work more than 80 hours a week and yet take home less than $30,000. This is the group that would have little chance of either paying for decent food or having the time to prepare it, let alone grow it.
So the poor are struggling and for them takeaways are a budgetary necessity which time constraints only make more unavoidable.
However, it's not the poor alone who are driving the rise in takeaway spending.
There is no evidence that the poor eat more takeaways than any other group in our society. There may be more takeaway outlets in poor areas, but all cohorts of Kiwi society eat them regularly, both rich and poor. The one advantage for the rich is that they can afford to spend a bit more on "healthier" versions of takeaways.
What is driving our obsession with takeaways? One factor is no doubt the recession, during which people have been looking for a cheap, convenient treat.
The business model of the convenience and takeaway food industry ensures that the resulting meal will be stacked full of sugar, fat and salt. This cocktail is lethal for one in four Kiwis who are a high risk for getting diabetes - a grisly condition that wipes eight years off your life.
For most Kiwis the excuse that we can't afford to eat healthily are pretty hollow, the truth is we are too lazy - or to be more politically correct, we're too time-short.
That raises the question of whether government health policy hasn't priced our time correctly. Or to translate that into English - whether our "free" public health system should make it more expensive for us not to avoid crap food and save the taxpayer some dosh in paying for the consequences - let alone extend our own years of health living.
A health sector that was cheaper to access for those who have taken preventive measures to avoid the consequences of the worst of our fake food - diabetes, cancer, strokes, obesity, sleep apnoea - would be a win-win.
A tax on "rubbish" food would provide the funds for the health sector to treat those too slack too avoid it. With such an abuser pays regime in place why would we care about those who eat the seeds of their own demise?
And what of that first group we discussed - the poor who can't afford to do anything else but turn up each night at the local chippie?
Another use of the tax on fake food would be to supplement their income so those better healthier eating options wouldn't be so out of reach.
When comparing groups of foods like different bread or meat products, the cheaper versions do tend to be unhealthier - substituting sugar, salt and fat for essential nutrients tends to do that.
However, if you get creative and prepare your own food then it is perfectly simple to eat healthy food on a limited budget.
Porridge is the cheapest, healthiest and most filling breakfast cereal around. Healthy fruit and vegetable snack options are often far cheaper than processed convenience foods. And for those who bemoan the availability of cheap soft drinks as opposed to the high price of milk, don't forget that the healthiest drink in the world gets pumped straight into every home for free. Water; it's a kind of magic.
Claims that fruit and veges are "too expensive" just don't hold any weight. Too expensive compared to what - fake food? If you buy fruit and veg that is in season, minimise reliance on the instant, nutrient-light, fake foods the supermarket peddles and go to your local farmers' market or greengrocer, then it is very affordable.
By contrast, the cheapness of many processed fake foods is a false economy - they don't fill us up so we end up buying more food anyway.
The more honest answer is that we can't be bothered preparing our own food - the convenience of fast food is a far more potent drawcard than price.
In an economist's parlance that means the price of self-inflicted harm from food is too low. Hence the argument to tax "rubbish" food.
If the cost of good food is such an issue, why do we throw so much of it away? Around 1.3 billion tonnes - or one third of the world's food - is lost or wasted every year. Each and every person in the developed world wastes an incredible 100kg a year (about 11 per cent of what we eat), particularly fruit and vegetables.
This is the problem with nutrient-rich food - it goes off - while fake food can sit on those supermarket shelves forever. It's a pity it contains so little goodness.
In short, whingeing about not being able to "afford" to eat healthily is hollow. Yes, eating healthily places demands on your time.
The price of leisure is too low, the price of investing in our health, too high. A corrective tax on fake food will correct that.
Gareth Morgan and Geoff Simmons of the Morgan Foundation are authors of the forthcoming book Appetite for Destruction.
