Obesity is a chronic, complex disease defined by the World Health Organization (WHO) as the excessive accumulation of fat in the body that can harm health. Since 1975, the prevalence of obesity has been increasing worldwide, making it a significant public health issue. Body mass index (BMI) is important in diagnosing obesity. BMI is calculated by dividing a person's weight (kg) by the square of their height (m²). BMI: weight (kg) / height² (m²). According to the WHO, a BMI between 30.0-34.9 kg/m² is classified as Class 1 obesity, between 35.0-39.9 kg/m² as Class 2 obesity, between 40-49.9 kg/m² as Class 3 obesity, and ≥50.0 kg/m² as super obesity. Obesity is closely related to increasing morbidity and mortality worldwide, and in obese patients, the incidence of diseases such as type 2 diabetes, hypertension, cardiovascular disease, dyslipidemia, coronary heart disease, obstructive sleep apnea, asthma, depression, other psychiatric disorders, and gastroesophageal reflux has increased. Treatment options for obesity include lifestyle changes, specific diets, diet-drug combinations, metabolic and various bariatric surgical options. Among these treatment options, metabolic and bariatric surgical procedures are considered the most effective methods for weight loss. Aspiration of gastric contents is a significant perioperative complication that can cause up to 9% of anesthesia-related deaths. Due to delayed gastric emptying in obese patients, the risk of aspiration is higher compared to non-obese patients. In obese patients, preoperative anesthesia management is more challenging, and the risk of pulmonary aspiration is greater. Since obesity is an independent risk factor for patients with a full stomach, and airway management can be difficult in these patients, it is essential to assess the aspiration risk in the preoperative period. Anesthesia guidelines recommend that to improve the quality and effectiveness of anesthesia care and reduce the severity of potential complications related to perioperative pulmonary aspiration of gastric contents, adults and children should be allowed to drink clear liquids up to 2 hours before elective surgery, and solid food consumption should be prohibited 6 hours before elective surgery. Recently, with the integration of ultrasound into anesthesia practice, ultrasound has been applied in various surgical procedures and clinical conditions. The use of ultrasound to evaluate the risk of aspiration in the preoperative period and to determine the residual gastric volume is increasingly being used in clinical practice. The use of gastric ultrasound to assess aspiration risk has also been increasing in pediatric patient groups and pregnant patients, similar to obese patient groups. In this study, the investigators' aim is to determine the relationship between BMI, fasting duration, and aspiration risk by assessing the gastric residual volume in the preoperative period through gastric ultrasonography in patients with obesity who will undergo bariatric surgery.