Australian diets have received a dismal score of C after findings that junk-food intake is three times greater than the recommended daily limit.
National eating habits were rated a paltry 61 out of 100 overall by the CSIRO, which found we are eating too much junk food too often. 
The Australian diet snapshot found men are more indulgent than women when it comes to consuming chocolate, soft drinks and alcohol.
Retirees and people working in healthcare and education have better diets than those in the construction industry. The survey also found Australia's healthiest eaters are on the NSW north coast.
The ratings were given out of 100 on the CSIRO Healthy Diet Score, which assesses the quality of people's eating habits against the Australian Dietary Guidelines.
More than 40,000 people were surveyed by the CSIRO about the variety, frequency and quality of the essential food groups they consumed, balanced against their intake of discretionary foods, which are high in sugar, refined starch and saturated fats and low in essential nutrients.
The results gave Australians a fail mark when it comes to consuming junk food. We also score poorly for eating insufficient fruits, vegetables and dairy.
CSIRO research director for nutrition and health Manny Noakes said the results raised concerns over national eating habits.
''The scores were fairly unflattering,'' she said. ''If we were handing out report cards for diet quality, Australia would only get a C.'' The survey found many people were having ''larger portions of junk food, more often''.
''This type of food is no longer just an indulgence, it's become mainstream, and Australians are eating it each and every day.'' Australian women have healthier eating habits than men. Women's overall diet quality scored 62, against 56 for men. Victoria was ranked just above NSW on the healthy diet score.
The best eaters by occupation included personal trainers and research professionals, while people working in construction, logistics and production scored lower than those who are unemployed.
Almost 15 million Australian adults are overweight or obese.
Professor Noakes encouraged people to test their own diet at csirodietscore.com.