I know people who took herba life (like a dietary supplement)they stop taking it and they gain more weight than what they started before taking it why?

Diet products. This is common with nearly all duet products. These products help you starve while dieting, turn down your metabolism, and when you start eating again your lowered metabolism leads to weight gain. Until diet is a lifestyle, with frequent low calorie and low carb meals weight loss will not be real or lasting. Avoid diet pills.