The aim of the study was to obtain information on the content of co-active compounds of a food supplement recommended as a weight reduction diet and on its short-term effectiveness and safety as a starter for lifestyle change. Eighty participants completed the protocol. The Sambucus nigra L. berry juice enriched with flower extract and tablets containing berry powder and flower extract provided a total of 1 mg anthocyanins, 370 mg flavonol glycosides and 150 mg hydroxycinnamates per day; the Asparagus officinalis L. powder tablets provided 19 mg saponins per day. After the diet, the mean weight, blood pressure, physical and emotional well-being and the quality of life had significantly improved (ITT analysis). The effectiveness and tolerability of the regimen were rated as very good or good by most of the completers. It remains to be established if any particular compounds contribute to the efficacy of the diet.