Parents are being warned not to over-feed their children after research found around one in 10 regularly serves up adult-sized portions of popular meals.
The poll of 1,000 parents also found that 79% of children aged one to four are often given more than the recommended portion size for their age.
The Infant and Toddler Forum (ITF), which commissioned the research, is warning that parents are increasing the chances their children will become obese.
As part of the study, parents looked at pictures of food to select the portion sizes they give their children, and were asked how often they give children certain foods.
The photos included snacks such as oatcakes and cheese, and popular meals such as spaghetti bolognese.
The results showed that around one in 10 parents usually serve their child close to an adult-size portion of spaghetti bolognese or cheese sandwiches.
Overall, 10% of all respondents gave snack portions that were too high. When it came to looking at pictures of cheese and oatcakes, 27% selected a portion size that was too big.
Some 71% of parents also routinely offered their child a bigger portion of crisps than recommended. More than a third of parents gave children a whole bag of crisps - nearly twice the recommended amount.
Almost half (45%) also offered crisps two or three times a week, 17% offered them four to six times a week and 6% gave them to their children every day.
Just a fifth (20%) gave crisps once a week.
The research also showed that 65% of parents routinely offered too much squash or fruit juice, and 24% of parents gave children a whole pack of jelly sweets as a treat (three times the recommended amount).
Some 73% of parents said they were worried their children do not eat enough while only a quarter (25%) worried their child might become overweight in the future.
Only one-quarter of parents said they were "very confident" about the amount of food to give their child.
Meanwhile, more than a third (36%) of parents also admitted they use food or drink as a way of calming children down when they are upset.
Gill Harris, child and clinical psychologist and a member of the ITF, said: 'It's never too early to start promoting healthy eating habits. Most toddlers are naturally better than older children and adults at regulating their food intake.
"They usually only eat what they need and don't overeat. However, portion size is critical. It's one of the main ways in which, as parents, we can inadvertently override children's self-regulation systems.
"Larger portions form our acceptance about what is an appropriate amount to eat and this becomes the norm. In other words, how much you offer often determines how much your child will eat and habits learned in early life generally tend to persist."
The ITF publishes images and further information on appropriate portion sizes for children.