Background: Increased consumption of sweetened beverages has previously been linked to the degree of childhood obesity. Objective: The aim of the present study was to assess whether the intake of sweetened beverages, candy, snacks or fast food at baseline in a multidisciplinary childhood obesity treatment program was associated with the baseline degree of obesity or the treatment effect. Methods: This prospective study included 1349 overweight and obese children (body mass index standard deviation scores (BMI SDS) ≥ 1.64) enrolled in treatment at The Children’s Obesity Clinic, Copenhagen University Hospital Holbæk. The children were evaluated at baseline and after up to 5.9 years of treatment (median 1.3 years). Results: Both boys and girls decreased their BMI SDS during treatment with a mean decrease in boys of 0.35 (p<0.0001) and in girls of 0.22 (p<0.0001) after 1 year of treatment. There were no associations between the baseline intake of sweetened beverages, candy, snacks, and/or fast food and BMI SDS at baseline or the change in BMI SDS during treatment. Conclusions: The intake of sweetened beverages, candy, snacks or fast food when entering a childhood obesity treatment program was not associated with the degree of obesity at baseline or the degree of weight loss during treatment.