Aim. To evaluate the clinical efficacy and safety of Dietressa at a dose of 6 tablets per day for 24 weeks in the treatment of patients with Class 1 obesity. To compare the clinical efficacy of two treatment regimens (1 tablet 6 times per day and 2 tablets 3 times per day) for 24 weeks in the treatment of patients with Class 1 obesity. Materials and methods. A clinical trial included 493 patients with Class 1 obesity from 18 to 65 years. The proportion of patients who lose greater than or equal to 5 percent of baseline body weight, an average decrease of body weight, a change in waist circumference, dynamics of the quality of life, and the safety of the therapy were assessed. Results. A weight decrease was established among patients without regard to the studied regimens of Dietressa (in a daily dose of 6 tablets with a six- or three-time intake). The goals were achieved by 49% [53%] of patients in the first treatment regimen (statistically significant compared to placebo therapy: p=0.04) [р=0.018]), 48% (51%) in the second (p=0.004 [р=0.0004]) and 48% [52%] of patients in the combined Dietressa group (p=0.0007 [р0.0001]). The average absolute weight loss was -4.44.2 [-4.84.2] kg in the Dietressa-1 group (p=0.0001 [р0.0001]) and -4.44.4 [-4.74.4] kg in the Dietressa-2 group (p0.0001) [р0.0001]). Against the background of the conducted therapy mental component was improved on week 4 (p0.0001) and 24 (p=0.006) as well as parameter of physical health on week 4 (p=0,003) and 12 (p=0,006). Waist circumference significantly decreased every 4 weeks in patients receiving Dietressa (p0.0001 for three comparisons between weeks). A 6-month course of Dietressa therapy demonstrated a favorable safety profile. The frequency of adverse events had no significant differences between Dietressa and Placebo groups. Conclusion. The monotherapy with Dietressa is safe, and it leads to at least 5 percent reduction in body weight during 24 weeks of therapy in patients with Class 1 obesity.