The team from Manchester Urban Collaboration of Health (MUCH), based at the University, say broader public health strategies are needed instead as obesity figures continue to rise.

Obesity has now become a global epidemic affecting children, adolescents and adults alike. The Manchester team reviewed of studies looking at dietary interventions to tackle the condition as latest figures now show in the UK 31% of boys and 28% of girls aged 2-15 are classed as either overweight or obese.

Dr Paula Whittaker, Clinical Lecturer in Public Health at The University of Manchester, said: "We conducted a systematic review of literature of interventions to increase fruit and/or vegetable consumption in overweight or obese children. We found narrow interventions focusing on single aspects of behaviour are unlikely to achieve long-term change."

Michael Bourke, a fourth year medical student at The University of Manchester who worked on the study, said: "We need to take a holistic approach and target behaviour change in multiple aspects of children's lifestyles and their surroundings, including nutritional education, parental support and physical activity."

Obese children are at increased risk of becoming obese adults, and therefore they are at risk of numerous other medical conditions in later life related to obesity. They are at risk of having a reduced life expectancy and the longer medical conditions are present, the greater the risk of complications and associated morbidity, resulting in more days away from work and education.

The research findings come ahead of world-leading speakers from across the globe descending on Manchester for the International Conference in Urban Health for Manchester Academic Health Sciences Centre in March.

Dr Arpana Verma, Director of MUCH at The University of Manchester, said: "Public health interventions helping global, national and local policy makers to make the right decisions for evidence-based policy is vital. Narrowing inequalities and inequities by helping children get the best start in life with policies that work is our best way of tackling the global epidemic in obesity.

"Our international conference will highlight what works from world-leading speakers across the globe."

The rising prevalence of overweight and obese children is the result of multiple factors, such as increased consumption of energy dense foods and a decrease in physical activity participation, Dr Verma added. "Changes in eating habits such as increased consumption of sugar sweetened beverages and high-fat foods accompanied by a decreased consumption of fruit and vegetables are associated with an increasing number of overweight children.

"Targeting children, particularly overweight children, with nutritional education is important as it helps children form healthier long-term eating habits."