Effect of Coffee and Tea Consumption on Adolescent Weight Control - a Randomized Clinical Trial

Patient Population The participants were recruited at the at the Obesity Clinic in the Pediatric Gastroenterology Unit at "Dana Dwek" Children's Hospital from January 2018 and December 2020. The Obesity Clinic is a tertiary referral center for children and adolescent with obesity and its complication. Adolescents aged 12-17 years with BMI in the 95th percentile or higher were eligible for the study. Exclusion criteria included major medical, chronic use of medication that may affect study outcomes or regular intake of some tea or coffee (individual for whom the intervention would likely produce relatively little change in habitual intake).

Study Design This is a randomized clinical trial, parallel-group study comparing 3 weight loss interventions comprising standardized dietary recommendation either with coffee (coffee group) tea (tea group) or placebo (herbal tea). The study consists of 2 weeks run in period and 24 weeks treatment period.

Intervention The 3 groups received similar weight reducing interventions comprising diets that will differentiated only with regard to the recommendation for coffee or green tea consumption. The standard intervention included 2 weekly family-based counseling concerning nutritional education (low carbohydrate, low glycemic index diet), behavioral counseling and physical activity.

The coffee group instructed to consume 2 cups of coffee a day, amount that was previously describe as beneficial in epidemiological studies and safe for children and adolescence. Each cup of coffee contains 250 ml of coffee, which contains approximately 80 mg of caffeine. The children were allowed to add milk to the coffee and sweeten it with artificial sweetener.

The green tea group will be instructed to drink 3 cups (230CC) of Chinese green tea (Wissotzky Tea Israel Ltd). Each tea bag contains 500 g fine dried herb parts. Each cup contains 84 mg total catechin and 32 mg caffeine. The participants were instructed to leave the tea bag for 2 minutes before drinking. The control group consumed 3 cups a day of Wissotzky- kid drink (Wissotzky Tea Israel Ltd), which is a drink that is marketed for children containing infusion of fruits and plants. Each tea bag contains 2.7 gr plants parts with no evidence of polyphenols or caffeine.