The Effect of Severe Weight Loss and Protein Intake on Bone

The purpose of this study is to learn whether the amount of dietary protein can influence bone health during the weight loss after weight loss surgery.

It is unclear whether the amount of protein in the diet during caloric restriction influences bone density. This information is important for determining optimal nutrient requirements during weight loss. This study will examine usual and higher dietary protein intake during severe weight loss following weight loss surgery on bone turnover, mass and quality in women, with the hypothesis that higher protein intake will reduce bone turnover and loss, and/or prevent the changes in bone quality associated with severe weight loss in women ages 18 to 70 years. Participants will be randomly assigned to one of 2 groups: A) weight loss with recommended level of protein intake, or B) weight loss with higher protein intake. A dietitian will provide instructions for a reduced calorie, well balanced diet throughout the 12-month study using a nutrition-education behavior- modification program. Participants will have the opportunity to speak with the dietitian about their diet by phone, or on-site twice per month. In addition they will be asked to take a daily vitamin/mineral supplement and, depending on their usual food intake, they may be asked to take a calcium tablet to meet the recommended intake throughout the study period. Bone, mineral, protein and lipid markers, and hormones that influence bones will be measured. These measurements will provide information about body composition (fat, muscle mass, and bone mineral density).

Participants will have the opportunity to speak with the dietitian about their diet by phone, or on-site twice per month

Inclusion Criteria: Women ages 18 to 70 who are undergoing gastric bypass surgery Must live in the geographic vicinity of Rutgers University Exclusion Criteria: Currently on any medication known to influence calcium or bone metabolism, including HRT, or with evidence of diseases known to influence calcium metabolism (i.e. metabolic bone disease, hyperparathyroidism, untreated thyroid disease, significant immune, hepatic, or renal disease, significant cardiac disease [i.e., heart attack or stroke in the past 6 months., abnormal EKG], active malignancy or cancer therapy within the past year) History of kidney stones Weight gain or weight loss (5% of body wt) within 3 months prior to recruitment Participation in other investigational studies during the 12-month study period Usually have a very high or low intake of calcium (more than 1500 or less than 500 mg per day)

Shapses SA, Riedt CS. Bone, body weight, and weight reduction: what are the concerns? J Nutr. 2006 Jun;136(6):1453-6. doi: 10.1093/jn/136.6.1453.

Riedt CS, Cifuentes M, Stahl T, Chowdhury HA, Schlussel Y, Shapses SA. Overweight postmenopausal women lose bone with moderate weight reduction and 1 g/day calcium intake. J Bone Miner Res. 2005 Mar;20(3):455-63. doi: 10.1359/JBMR.041132. Epub 2004 Nov 29.

Goode LR, Brolin RE, Chowdhury HA, Shapses SA. Bone and gastric bypass surgery: effects of dietary calcium and vitamin D. Obes Res. 2004 Jan;12(1):40-7. doi: 10.1038/oby.2004.7.

Riedt CS, Brolin RE, Sherrell RM, Field MP, Shapses SA. True fractional calcium absorption is decreased after Roux-en-Y gastric bypass surgery. Obesity (Silver Spring). 2006 Nov;14(11):1940-8. doi: 10.1038/oby.2006.226.

Sukumar D, Ambia-Sobhan H, Zurfluh R, Schlussel Y, Stahl TJ, Gordon CL, Shapses SA. Areal and volumetric bone mineral density and geometry at two levels of protein intake during caloric restriction: a randomized, controlled trial. J Bone Miner Res. 2011 Jun;26(6):1339-48. doi: 10.1002/jbmr.318.

Ogilvie AR, Schlussel Y, Sukumar D, Meng L, Shapses SA. Higher protein intake during caloric restriction improves diet quality and attenuates loss of lean body mass. Obesity (Silver Spring). 2022 Jul;30(7):1411-1419. doi: 10.1002/oby.23428. Epub 2022 May 11.