The introduction of fast food has contributed to the country's ever-growing waistlines.

How has the Kiwi diet changed? Here's a run down as part of the Facts of Life series.

Whether we eat more overall is not clear from national diet surveys, says Otago University professor of nutrition, Jim Mann. However, given exercise rates have stayed static and obesity is climbing, logic says we must be consuming more calories.

"Where are the calories coming from? We're not eating more protein so they must be coming from carbohydrates and probably sugar."

The other big change has been the increase in junk food, processed food, ready-to-eat meals and eating out. McDonald's arrived in New Zealand in 1976, opening its first restaurant in Porirua.

READ MORE of the Facts of Life:

* Men at work

* In the family

* What ails us

* The daily diet

* How we're homed

But even when Mann arrived in New Zealand from Britain 30 years ago restaurant meals were rare.

"I was a teenager in 1965. We were very much having meat and two veg, meat and three veg kind of food. We certainly weren't getting all that prepared food; nobody was eating out. I think in the first half of those 50 years there was probably much less change than there's been since the 1990s."

Convenience meals first made it into the Consumers Price Index goods basket in 1999 and 2-minute noodles were added three years later.

If the Kiwi love affair with carbs and sugar continues, Mann expects the next 50 years to see a reversal in declining heart disease rates and an increase in obesity-related cancers - "with dire consequences".

"What will happen to our eating habits I don't know. I think politics will be an important determinant of that."

Facts of Life: Click or touch the graphics to see how things have changed.