Many people view fennel tea as a weight loss aid because it acts like a diuretic. According to Burgess, diuretics help your body get rid of salt and include your kidneys to release more salt into your urine. “As the sodium leaves your body, it also takes water from your blood, effectively helping you lose water weight,” she explains. But while the number on the scale may decrease temporarily, this is not actual weight loss.
https://www.psychreg.org/effective-belly-fat-burning-drinks-that-really-work/