Nano Girl Michelle Dickinson: How to beat the new 'normal'

A recent ministry estimate shows 31 per cent of New Zealand adults are obese, an 18.6 per cent increase over the past 25 years. Photo / Getty Images

As bigger becomes the new "normal", people are less likely to recognise health problems associated with their weight.

Are you underweight, overweight or an ideal weight for your height?

Most people will relate that question to their bathroom scale weight, possibly subtracting a few optimistic kilos along the way. In New Zealand 1.2 million of us are obese - that's three in 10 adults and one in nine children.

Weight categories are usually based on your body mass index, an estimate of the amount of muscle, fat, and bone a person has. When 641 Dunedin and Christchurch women were asked which BMI category they believed they fell into, 66 per cent identified correctly.

However, the overweight and obese women were much more likely to underestimate their BMI than the normal weight women according to research published in the New Zealand Medical Journal this week. This backs a British Medical Journal study where only 11 per cent of obese women accurately acknowledged they were obese, with most describing themselves as "very overweight" or "just right".

Not knowing that you are heavier than you think may not seem like a critical issue, but in the New Zealand study, all of the women were 12 weeks pregnant. Research shows that the amount of weight gained during pregnancy can affect the immediate and future health of a woman and her baby.

Because the women, particularly those who were overweight and obese, lacked accurate knowledge of their own current body size, they were likely to have an inaccurate estimation of how much weight they should gain during their pregnancy. The Ministry of Health guidelines state that an obese mother should gain only 5kg-9kg through her pregnancy compared to the suggested 11.5kg-16kg pregnancy weight gain recommended for a normal weight female carrying a single child.

Gaining too much weight during pregnancy can lead to several health risks for expectant mothers, including high blood pressure, loss of pregnancy, and gestational diabetes. There is also an increased health risk for the baby during pregnancy as well as an increased chance of childhood obesity after birth. The dangers of underestimating BMI creates a multigenerational cycle as highlighted in a different NZMJ article where nine out of 10 parents of obese children aged 2-4 years believed that their children were a normal weight.

As a nation we are getting fatter. A recent ministry estimate shows 31 per cent of New Zealand adults are obese, an 18.6 per cent increase over the past 25 years.

Because the women, particularly those who were overweight and obese, lacked accurate knowledge of their own current body size, they were likely to have an inaccurate estimation of how much weight they should gain during their pregnancy.

As bigger sizes become the new "normal", researchers suggest people are less likely to recognise the health problems associated with their weight. Obesity is a big killer, putting adults at an increased risk of health problems including coronary heart disease, high blood pressure, stroke, type 2 diabetes and cancer.

So what can be done? First, by calculating your BMI you can determine your weight category. BMI is calculated by taking your weight in kilograms and dividing it by the square of your height in metres. A healthy BMI is classed as between 18.5 and 24.9, although muscular athletes may come in slightly higher.

Second, we need to accept responsibility for our children's health as they grow up in an obesogenic environment where food promoted through sports, television and the internet encourages them to consume cheap foods high in fat, sugar and salt.

Overweight and obesity costs our country up to $849 million a year just in health care costs and lost productivity.

With statistics estimating that 80 per cent of obese children will become obese adults, not acting now to tackle our weighty issues and reduce generational obesity gives us a clear insight into how our country's future healthcare funds will be spent.