Researchers have followed a group of 2 years olds and have found that those who have more than 1 cup of 100% fruit juice a day (8 oz, 230mL) are at higher risk of being overweight at 4-5 years of age. It is advised to avoid excessive consumption of juice in children, even if it 100% fresh and does not contain any added sugars.
Shefferly A, Scharf RJ, DeBoer MD. Longitudinal evaluation of 100% fruit juice consumption on BMI status in 2-5-year-old children. Pediatr Obes. 2016;11(3):221–7.