Advisers on nutrition say no more than 5% of daily calories should come from added sugar, in line with new World Health Organization proposals,
Responding to the SACN report on Carbohydrates and Health, Professor Neena Modi, President of the Royal College of Paediatrics and Child Health, described the findings as "sobering".
The Scientific Advisory Committee on Nutrition (SACN), which advises Public Health England and other government agencies on nutrition, wants the recommended daily intake of sugar to be halved to reduce obesity risk and improve dental health.
Prof Ian Macdonald, chair of the working group of the committee, said: "The evidence is stark - too much sugar is harmful to health and we all need to cut back.
"The clear and consistent link between a high-sugar diet and conditions like obesity and type 2 diabetes is the wake-up call we need to rethink our diet. Cut down on sugars, increase fibre and we'll all have a better chance of living longer, healthier lives."
The government said it was accepting the recommendations and will be using them to develop its national strategy on childhood obesity, which is due out later this year.
The main sources of sugar in the diet are sweetened drinks and cereal, confectionery, fruit juice, and sugar added at the table. A single can of fizzy drink contains about nine teaspoons of sugar.
According to health experts, 5% of daily energy intake is the equivalent of 19g or five sugar cubes for children aged four to six, 24g or six sugar cubes for children aged seven to 10, or seven sugar cubes for those aged 11 and over, based on average diets.
Professor Modi added: "It is salutary to learn that there has been no reduction in the population’s sugar intake over the last 5 years. It’s clear that nudging people into changing behaviours isn’t working, nor is relying on industry to reduce sugar in its products voluntarily.
"Instead there is a need to be bold and act decisively. We urge Government to evaluate the health impact of taxes on sugary drinks and unhealthy foods as a matter of urgency and put resources into a large-scale public education campaign on healthy eating and living. We call too for investment in basic science and applied research to identify effective interventions that prevent overweight and obesity taking a hold in infants and children. The nation requires a visionary approach and incremental improvements adopting a life-course approach; there are no simple solutions. We very much hope these will be part of the Government’s obesity plan due to be announced later this year."