Obesity is likely to be the disease of the 21th century. The growth of obesity is worldwide, a pandemic, and has increased globally in the last 30 years. Developed countries were more affected, but developing countries have increasingly contributed to this epidemic as they continue to modernize. The national and global burden of obesity, with its public health and financial implications, is projected to increase markedly in the next two decades.

the study aimed to assess the effect of Vit D supplementation on preventing altered levels of calcium, Vit D, and parathormone after laparoscopic sleeve gastrectomy.

Inclusion Criteria:

• Adult
• male or female
• from 18 to 60 ages
• BMI: 40 kg/m2 or > 35 kg/m2
• comorbidities e.g., hypertension and DM
• conservative management for obesity failed in at least 2 years

Exclusion Criteria:

• BMI > 60
• history of bariatric surgery
• symptomatic reflux oesophagitis
• stomach cancer
• active peptic ulcer disease
• alcohol or drug abuse
• major psychological disturbance
• major eating troubles
• risky anesthesia
• risky surgery.