Parents are feeling the heat. With one in five children already overweight by the time they start school, the pressure is on to provide the healthiest possible nutritional start for little ones as they move from formula or breast milk to solid foods.
But a BBC Panorama investigation into food for the under-fives found that easy answers to healthy eating can be as hard to come by as a full night's sleep and a long lie-in.
For the parents of the 1.5m children who regularly attend nursery in the UK, the nutritional puzzle is even harder to piece together.
While celebrity chef Jamie Oliver successfully raised the profile of the importance of nutritional standards being met in school dinners, Scotland is the only place where similar set guidelines apply to nursery food.
In England, government advice for care of children aged one to five states they should be eating a "healthy, balanced and nutritious" diet, but does not define what that diet should contain. England's strict nutrient-based standards for primary schools do not apply in pre-school settings.
Salt should not be added to any food aimed at young children
Northern Ireland does not use nutrient based standards at all and in Wales they are being piloted for schools, and are recommended for early years.
As part of an ongoing study of nursery food across England, Trading Standards in
surveyed the food at 10 nurseries that volunteered to take part.
They found that while the nurseries were doing well in keeping salt levels low, none of them were providing enough fat or energy in their meals.
Sue Powell of Hampshire Trading Standards said the focus on fruit and vegetables - key to a healthy adult diet - omits the reality that growing toddlers need a higher fat diet.
"I think the perception is that maybe giving the children too much fat is actually a bad thing and we forget that children do actually need fat, they need carbohydrate and they need protein to actually give them the energy that they need."
Not enough energy
The survey - the national results of which are due to be released next month - found that most nurseries were not serving enough oily fish and none were providing enough zinc in their meals.
Jacqui Horton of Woodlands Nursery - one of those in the initial findings in Hampshire - said the message of 'five a day' had been heard loud and clear, but the survey found that they had not been giving the toddlers enough carbohydrate.
"The plate was being filled with those five fruit and veg for their pudding and their main, and we weren't putting enough energy on. The energy was on the plate, but just not enough of it."
Professor Terry Wilkin of Peninsula Medical School in Plymouth has studied the impact of poor diet in the under-fives and warns that all the attention on keeping school age children fit and healthy - from healthier meals to cutting down on television and screen time to after school physical activities - could be missing the age group where it matters the most.
"These are not factors that operate in a two-year-old's life and yet the evidence is from other studies that it may even be younger than two years old that this weight gain begins to occur."
In their search for the best possible nutritional mix for their children at home, many parents have turned to kiddie food guru Annabel Karmel for help with recipes and diet plans.
Ms Karmel's best-selling range of ready meals for toddlers promise no added colours, flavourings or preservatives.
SUGAR, FAT and SALT
Sugar: 15g sugar per 100g is high in sugar, 5g or less is low
Fat: 20g fat per 100g is high in fat, 3g or less is low
Salt: 1.5g salt per 100g is high in salt, 0.3g or less is low
Source: Food Standards Agency
But her toddlers' lasagne does contain added sugar - more than twice as much as an ordinary supermarket lasagne.
Ms Karmel said children's palates prefer sweeter foods and the sugar was added to make the meal more appealing for fussy eaters. She added that the company plans to no longer add sugar to its meals and to replace the sugar in the lasagne with fruit juice.
Making the toddlers' meals more palatable is also why Ms Karmel said her range of ready meals have added salt - despite government recommendations that parents cooking at home should not add salt to the food they cook for toddlers.
Shefalee Loth, a childhood nutrition expert with the consumer group Which?, said Annabel Karmel's lasagne contains 1 gram of salt - half of the daily recommended maximum salt intake for a one to three year old.
"So just by eating this one meal, they've consumed half of their maximum daily salt allowance in fact for a one-year-old, a two-year-old, it's actually very high in salt."
Ms Karmel defended the salt content as appropriate as part of a balanced diet and said that making the food taste good ensures that children who are fussy eaters will eat the meals. She added that a typical one-year-old would likely only eat half a portion of her lasagne.
"Within part of a balanced diet, I don't think this is an excessive amount of salt," she told Panorama's Shelley Jofre.
The weekly shop can be a scramble for busy parents
Ms Karmel said the advisory group Consensus Action on Salt and Health (CASH), "thought that a main meal for a child of one to four with one gram of salt was absolutely fine."
But in a statement to the BBC, CASH said it believes a gram of salt in a single meal is too high for a child aged one to three.
"For a child under the age of four, any main meal should have a third or less of the maximum recommended intake of 2 grams, especially if they are being marketed as a healthier alternative to an adult meal.
"It should be an absolute requirement that the packaging of products targeted at children clearly shows how much of the children's recommended daily intake of salt they contain. Salt should not be added to any food aimed at young children."
Nutritionist Shefalee Loth said parents would have an easier time making an informed choice if meals such as the Annabel Karmel range for children had the same labelling as adult ready meals - including telling parents at a glance whether a serving of food is high or low in sugar or salt.
"As an adult, we can go into a supermarket and buy a ready meal and know how much of our daily guideline amount that meal is going to meet. If they were going to buy one of these targeted meals, you just wouldn't know."
Panorama: What's Really in Our Kids' Food, BBC One, Monday, 25 January at 2030GMT.
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