The Food Standards Scotland (FSS) board was set up in April.
It has recommended that Scots should increase their fibre intake to 30g per day and have no more than 5% of their total energy from sugar.
Previous dietary goals, including a target to have no more than 11% energy intake from sugar, have not been met.
The current intake of food energy from sugar is 14.4%, the FSS said.
It said 50% of the sugar consumed by Scots comes from discretionary foods, such as biscuits, cakes, confectionery, savoury snacks and sugar-sweetened drinks.
The FSS has published a situation report which collates and presents current evidence to provide information for policymakers.
The report says:
FSS chair Ross Finnie said: "The Scottish diet is not improving and the problem of diet-related ill-health is now spanning the generations.
"There is a disconnect between the scale of the problem and how healthy people believe their diet to be.
"We all need to recognise there is a problem and everyone including consumers, the food and drink industry, retailers, media and government has a part to play in finding a solution."
Public health minister Maureen Watt said:"We recognise that there are issues with the Scottish diet and that many of these are long-standing, however there are some indications of progress in recent years, for instance a reduction in the purchase of sugary drinks.
"We are working to ensure that everyone in Scotland has the opportunity, ability and confidence to access a healthy diet for themselves and their family."
Scotland's new food standards body has recommended tougher targets for healthy eating after finding "little or no progress" over the past 15 years.