It's time to tackle over-eating from birth to make sure children get the best start in life, according to Public Health England.
It comes as government advisers publish new guidance – the first in more than 20 years – on feeding babies.
That report suggests three-quarters of UK babies and toddlers may be eating more calories than they should.
The same proportion weighed more than the ideal weight for their age, when plotted on growth charts.
The data comes from the Infant Feeding Survey and the Diet and Nutrition Survey of Infants and Young Children carried out in 2010 and 2011.
Public Health England says more up-to-date statistics are needed and is recommending the Department of Health and Social Care considers this.
Experts know that people who are overweight as children are more likely to be overweight as adults.
A link with diet in early infancy is less clear.
Nearly a quarter of children in England are obese or overweight at four to five years old.
Part of the next phase of the government's plan to tackle childhood obesity includes examining whether baby food is healthy enough and whether it contains too much sugar.
The new infant feeding guidelines from the Scientific Advisory Committee on Nutrition (SACN) recommend:
- Babies should be exclusively breastfed for around the first six months of life
- Solid foods can be introduced at around six months
- Cows' milk should not be given until 12 months
- Avoid high sugar or high salt foods
- Foods containing peanut and hens' eggs can be introduced at six months because delaying this might increase the risk of food allergy (but seek advice if there is a strong family history of food allergy)
Prof Mary Fewtrell, from the Royal College of Paediatrics and Child Health, said: "We note the concerns raised by SACN about the significant proportion of infants with energy intakes above requirements and the proportion exceeding growth standards for their weight, and support the need for monitoring the prevalence of overweight and overfeeding in infants, and addressing high energy intakes in this age group."
Prof Louis Levy, head of nutrition science at PHE, said: "The evidence suggests many infants are too heavy and are consuming more than they require. Exclusive breastfeeding until six months of age and not introducing solid foods until around this time would likely help towards healthier weight gain.
"Further consideration is needed on ways to monitor overfeeding and overweight prevalence in infants, to help give them the best start in life."