The study by Expand New Research linked fast food to numerous health problems in Kiwi kids, and indicated children who eat fast food three or more times a week have a higher chance of developing asthma, eczema, and hay fever.
Ms MacPhail, who on medical advice has completely cut out processed and fast food from her diet, said she was not surprised by the findings.
"It's the preservatives, the salt, but it's also the other preservatives such as food colouring," she said.
"In your chicken nuggets you're not just getting breast chicken or flesh from the chicken - you're getting all the bones and everything else crushed in."
In contrast the study found that eating three or more servings of fruit a week could cut the chance of severe asthma, eczema, and hay fever by 11 to 14 per cent across the age groups.
Eating fresh fruit can act as a protective factor against allergy-based conditions.
The study, published in the journal Thorax, surveyed more than 400,000 children from 51 countries. More than 26,000 of them were New Zealanders.
Ms MacPhail said her ballooning weight was because of convenience food and stress brought on by her ex-husband's work, which meant the couple moved home regularly in the early stages of her marriage.
She says she is now on a range of medications to control her various ailments. "I'm on Flixotide and Ventolin for my diabetes. I'm on a whole list of medication because once you're diabetic [you need it]. Most people need a trigger and my obesity, at [143kg], triggered my diabetes."
Despite now adhering to a healthy lifestyle, eating fresh foods, walking regularly and feeling much better, she says it is sometimes a struggle.
"The chemicals in the processed food also triggered the asthma and it has to be controlled by more chemicals, and it's not evening out. My asthma is not getting better."
Ms MacPhail advises young people to stick to one take-away a fortnight and eat a balanced diet, including lots of fruit and vegetables. She says Wairarapa parents need to lead by example.
"Their mums haven't taught them how to cook. It's got to start at home. You can't blame the manufacturers like KFC, McDonald's, Subway and Burger King," she said.
The research was led by Professor Innes Asher from the University of Auckland, who said the results were concerning because fast-food outlets were on the increase.
"The bottom line is that people should be careful about the amount of fast food they eat."
Though the exact reason why consumption of fast food is linked to these conditions is unknown, Prof Asher said high levels of trans fats and saturated fatty acids were possible contenders.
These acids are known to affect immunity, which could lead to allergy-related conditions.
If causality is established, "the findings have major public health significance owing to the rising consumption of fast foods globally", she said.
