. 2018 Apr 7;9(2):114–127. doi: 10.1093/advances/nmx024

TABLE 1.

Changes occurring following conventional weight loss vs. bariatric surgeries and their expected effect on bone metabolism¹

	Conventional weight reduction	Expected effect on bone	Bariatric surgery	Expected effect on bone
Mechanical unloading	↓ Mechanical loading on bone	^_	↓ Mechanical loading on bone	^_
Nutrient intake and malabsorption	↓ Calcium, protein, and other nutrient intake	^_	↓ Calcium, protein, and other nutrient intake	^_
	↓Calcium absorption	^_	↓ Calcium, protein, and vitamin D absorption²	^_
Changes in adipose	↓ Leptin (peripheral rout)	^_	↓ Leptin (peripheral rout)	^_
hormones	↑ Adiponectin	?	↑ Adiponectin	?
	↓ Estrogen	^_	↓ Estrogen	^_
Changes in	↑ Ghrelin	+	↓ Ghrelin	^_
gastrointestinal	↓ GIP	^_	↓ GIP	^_
hormones	↓ PYY	+	↑ PYY	^_
	↓ GLP-1	^_	↑ GLP-1	+
	↓ Amylin	^_	↓ Amylin	^_
	↓ Insulin	^_	↓ Insulin	^_

¹BS, bariatric surgery; GIP, gastric inhibitory polypeptide; GLP-1, glucagon-like peptide-1; PYY, peptide YY; 25(OH)D, 25-hydroxyvitamin D; ↓, decrease; ↑, increase; +, positive effect; −, negative effect; ?, unclear effect.

²Vitamin D deficiency has been shown to be accelerated after malabsorptive BS procedures and in the long term after restrictive procedures. After conventional weight loss 25(OH)D levels may increase owing to its release from the adipose tissue.