Still not enough oily fish and iron on the menu

The survey was split into two stages. The first stage was a face-to-face interview with the participant, or their parent or guardian. The interview included questions about shopping, food preparation and cooking skills. The interviewer also took height and weight measurements. The participants were then asked to complete a four-day food diary listing everything they ate or drank.

The second stage of the survey was a visit to a nurse, who took further body measurements, a blood sample and a 24-hour urine sample.

On a positive note, the survey suggested that the recent 'five-a-day' campaigns have made a difference to the average diet. The survey showed that, on average, adults are now eating at least four portions of fruit and vegetables a day, and more than a third of adults are eat the recommended five portions. However, this increase in the amount of fruit and vegetables eaten wasn't seen in teenagers, with only seven percent of girls and 22 percent of boys meeting the five-a-day guidelines.

Saturated fats and added sugar were both shown to make up less of the average diet than they did 10 years ago. However, the levels seen in the survey were still higher than those recommended for a healthy diet.

One of the other key findings was that girls aged between 11 and 18 had worse diets overall compared with boys of the same age.

Commenting on the recent figures, Dr Annabel Bentley, assistant medical director at Bupa, said: "It's great to see that people have started making changes to their diets, but the hard work isn't over yet. This comprehensive survey suggests that teenagers should be encouraged to eat a healthy, balanced diet and that teenage girls in particular should make sure they get enough iron."