Obesity surgery is a highly effective treatment for morbidly obese patients. Despite effective weight reduction, the impact of bariatric surgery on bone is a major concern. Mechanisms of the deleterious effect include calcium and vitamin D malabsorption with secondary hyperparathyroidism (SHPT), deficiency in other nutrients and alterations in gut-derived hormones. Sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB) are the most frequently performed bariatric procedures in the past few years. RYGB and SG have comparable effects in terms of energy and food restriction and subsequent risk of micronutrient and protein deficiencies in the long-term follow-up period. Most of the publications report bone mineral density (BMD) loss after bariatric surgery. It is interesting that hip bone loss is more significant than spine BMD loss. Clinical Practice Guidelines recommend calcium and vitamin D supplementation postoperatively after malabsorbtive obesity surgical procedures with dose adjustment by a qualified medical professional based on serum markers. Oral doses of vitamin D may need to be as high as 50000 IU 1 to 3 times weekly or daily. Vitamin D loading and ongoing vitamin D, calcium, and BMI-adjusted protein supplementation in combination with physical exercise may decelerate the loss of BMD after bariatric surgery.