Social desirability may explain why some caregivers of overweight children report less frequent high calorie food intake.

•209 caregivers of preschoolers attending Head Start completed measures of BMI, child food frequency and social desirability.•Social desirability scores were higher in caregivers of overweight children reporting low vs. high snack/fast food intake.•Child weight status was a significant moderator of caregiver reports of child fast food consumption and social desirability.•There were no social desirability effects for caregiver reports of child fruit and vegetable consumption.•Social desirability may partly explain why caregivers may under-report their overweight children’s high calorie food intake.