Nutritionists are concerned that parents have been bombarded with health messages and do not realise that growing children frequently need higher levels of sugar, fat and carbohydrate than adults.
Malnutrition, once associated with slums, is said to have become an increasing problem for middle-class families over the past 15 years. The victims of so-called "muesli-belt malnutrition"are at risk of stunted growth, anaemia, learning difficulties, heart disease and diabetes.
Nutrition expert Dr Andrew Hill says that he has seen cases of malnourished children after parents fed them with skimmed milk or low-energy products rather than full-fat milk when they were weaned.
"Young growing infants they need full fat milk until they are at least four or five years old," said Dr Hill, senior lecturer in behavioural sciences at Leeds University.
Dr Jackie Stordy, research nutritionist at Surrey University, did a study which looked at children - aged from three months to a year - and the food that their mothers were feeding them. It found four-fifths of mothers were putting small children on a "nursery starvation diet" of vegetable and fruit purees and low-fat yoghurts rather than traditional foods.
"We asked them why they were giving their children these foods and what they were trying to do. Basically, they were under the misguided notion they were healthy," said Dr Stordy. "There was a perception that fruit and vegetables were good foods and things like meat weren't."
The researchers also analysed the meals the mothers gave their children and found them to be low in energy and less nutritionally complete than manufactured baby food. "There is this concept within the public arena of something called healthy eating but which is totally inappropriate for young children," said Dr Stordy, who added that fears over obesity can be exaggerated.
"Up until the age of 30 there are more people with unacceptably low Body Mass Indexes (BMI) than high BMIs," she said. "Around 20 per cent of this population have unwisely low BMIs compared to nine per cent who have unwisely high.
"Looking at hospital admissions in paediatrics between one and five per cent - as many as one in 20 - are brought in because of malnutrition or failure to thrive."
"Things we advise adults to eat are not appropriate for children," said Wynnie Chan, nutrition scientist at the British Nutrition Foundation. "It's very difficult for parents to strike a balance. They need to watch what they are giving children to ensure it is a balanced diet with lots of different foods which meet their requirements. The important thing is to make sure children become more physically active rather than restricting their food."