Children aged four to 10 are consuming twice as much sugar as they should, while older children have three times too much, a major survey has revealed.
The National Diet and Nutrition Survey, funded by Public Health England and the UK Food Standards Agency, also found that people in the UK are not eating enough fruit and veg, while consumption of red meat and saturated fat is still too high.
Children aged four to 10 drank 100ml of sugary drinks per day on average in 2012/14, a drop from 130ml per day in 2008/10, the survey showed.
But sugar still makes up 13% of children's daily calorie intake, more than twice the 5% recommended limit.
Those aged 11 to 18 have daily diet made up of 15% sugar - three times the recommended amount. Meanwhile, adults aged 19 to 64 are also heavy consumers, with 12% of their diets made up of sugar. These figures have remained more or less the same since 2008.
The survey also found that people in the UK continue to consume too much saturated fat and not enough fruit, vegetables and fibre.
Children aged four to 10 have diets in which 13% of their daily calorie intake comes from saturated fat, compared with a target of less than 11%. The figure is 12.6% for those aged 11 to 18, while adults get 12.7% of their energy from saturated fat.
Average intake of red and processed meat should also not exceed 70g per day, but men still eat too much while women are reducing the amount they consume.
There has been no change in consumption of fruit and vegetables in almost a decade, with those aged 11 to 18 managing just 2.8 portions per day on average.
Adults eat four portions, while there are no specific recommendations for young children.
Just 27% per cent of adults, 35% of those aged 65 and over and 8% of 11 to 18-year-olds currently meet the five-a-day recommendation for fruit and vegetables.
Typical consumption of oily fish among all age groups was well below the recommended one portion per week, and there has been little evidence of change over time.
Oily fish includes anchovies, mackerel, herring, pilchards, salmon and fresh tuna.
Dr Alison Tedstone, chief nutritionist at PHE, said: "This data provides compelling evidence that we all need to eat more fruit, veg, fibre and oily fish and cut back on sugar, salt and saturated fat to improve our health.
"While it is encouraging that young children are having fewer sugary drinks, they still have far too much sugar in their diet overall, along with teenagers and adults.
"To help tackle this, PHE is launching a programme to challenge the food industry to remove at least 20% of the sugar in its products by 2020. It's an ambitious programme, a world first, and will be a significant step on the road to reducing child obesity levels."
Professor Neena Modi, president of the Royal College of Paediatrics and Child Health, said: "The results of this survey are extremely worrying."
She added: "At a time when one in three 10-year-old children are overweight or obese, and one in three five-year-olds has tooth decay, the health risks posed by failure to tackle sugar intake are serious. An overweight or obese child is highly likely to be an overweight or obese adult, increasing the risk of developing the risk of developing heart disease, type 2 diabetes and some cancers.
"This is why we are surprised the long-awaited UK Government childhood obesity strategy did not include a number of recommendations aimed at protecting children, such as a ban on advertising junk food and limiting their sale around schools. We call for these measures to be reconsidered in order to safeguard the health and well-being of all UK children."
:: The survey was carried out among 1,288 adults and 1,258 children who completed a three or four-day food diary.
The data shows that there has been slight reduction in sugar intake among children aged four to 10 since 2008, although it is still way above recommended levels.
In 2008/09, sugar intake was 14.4% of daily calories, rising to 15.1% in 2011/12. This has now dropped to 13.4%.