Introduction. Obesity causes thrombophilia and many coagulation problems related to slowing the capillary flow. We aimed to evaluate rapid weight loss outcomes in the early period after bariatric surgery on the coagulation system. Materials and Method. A prospective study enrolled 28 patients with a BMI > 40 kg/m2 who underwent bariatric surgery. Preoperative and postoperative (first and third months) demographic criteria—such as age, gender, weight, height, and alcohol and tobacco use, and biochemical parameters such as PLT, PT, aPTT, INR, bleeding time, coagulation time, fibrinogen, D-dimer, albumin, calcium, ionized calcium, vitamin D, and PTH—were analyzed. Results. We found that both bleeding and thrombotic parameters increase in early-slowing surgery. The first-month platelet levels were significantly different from the preoperative values (p