The report, Food for Thought, also found that children from families on lower incomes eat less nutritionally balanced diets and are more at risk of being either underweight or overweight.
The report, which is supported by Sainsbury's and includes a survey of 2,000 children aged from four to 14, parents and playworkers at out-of-school clubs in England and Wales, found that while only three out of ten parents thought their children understood about healthy eating, eight out of ten children knew they should eat five portions of fruit and vegetables a day.
KCN chief executive Anne Longfield said, 'Children can and do differentiate between "good" and "bad" foods, but the reality of everyday life means that compromises have to be made. Ensuring that all children have access to healthy food has to be a major priority. From school dinners to the family dinner table, we all have a part to play.'
As part of the research, around 1,000 children and their parents were asked to keep a weekly food diary. These revealed that children had a varied diet, typically including cereal or bread for breakfast and a packed lunch or school dinner. Pasta, pizza and the traditional 'meat and two veg' were the most popular choices for the evening meal, and three-quarters of children ate with their family every day.
But the report raised concerns that fatty and sugary foods, pizza, bread and potatoes made up too much of children's diets.
The children also had strong opinions about their weight, with seven out of ten saying that 'fat people do not like being fat' and that 'slim people like being slim'. Girls tended to worry more about food and being 'fat'
than boys, while children aged eight and above were more likely to worry than younger children. More than seven in ten parents agreed that children ate too many sugary, fatty and snack foods, but four in ten parents regularly gave their children money for crisps and sweets.
Food for Thought is the first project to be carried out by the KCN's new Research Foundation. A survey is to take place each year to help build up a picture of children's lifestyles across the UK.