Lately there is some discussion about an inverse relationship exists between calcium intake and obesity markers such as body weight, weight gain or body fat percentage. However, numerous studies question the idea whether adequate calcium nutrition can prevent or even reduce obesity. However, the disagreement from many studies seems to have more to do with the interpretation of the data than the data itself, with different hypothesis which could be valid in different specific populations. Still, the major finding we present here are in line with previous research demonstrating that lower levels of serum calcium are common after bariatric surgeries.