Does bone loss begin after weight loss ends? Results 2 years after weight loss or regain in postmenopausal women

Abstract

Objective: Short-term weight loss is accompanied by bone loss in postmenopausal women. The longer-term impact of weight loss on bone in reduced overweight/obese women compared with women who regained their weight was examined in this study using a case-control design.

Methods: Postmenopausal women (N = 42; mean [SD] body mass index, 28.3 [2.8] kg/m; mean [SD] age, 60.7 [5.5] y) were recruited 2 years after the start of a 6-month weight loss trial; those who maintained their weight (weight loss maintainer [WL-M] group) were matched to a cohort of women who regained their weight (weight loss regainer [WL-R] group). Serum hormones and bone markers were measured in a subset. Bone mineral density (BMD) at the femoral neck, trochanter, spine, radius, and total body, and soft-tissue composition were taken at baseline, 0.5 years, and 2 years.

Results: During weight loss, both groups lost 9.3% (3.4%) of body weight, with no significant difference between the groups. After weight loss, weight change was -0.1% (2.7%) and 6.0% (3.3%) in the WL-M (n = 22) and WL-R (n = 20) groups, respectively. After 2 years, both groups lost BMD at the femoral neck and trochanter (P ≤ 0.01), whereas only the WL-M group reduced BMD at the 1/3 radius (P < 0.001). There was greater BMD loss at the trochanter (-6.8% [5.7%]) and 1/3 radius (-4.5% [3.3%]) in the WL-M group compared with the WL-R group after 2 years. Multiple linear regression showed that change in leg fat mass (but not trunk fat) contributed to trochanter BMD loss (P < 0.05).

Conclusions: After 2 years, there is no BMD recovery of weight reduction-induced bone loss, irrespective of weight regain. These data suggest that the period after weight loss may be an important point in time to prevent bone loss for those who maintain weight and those who regain weight.

Figure 1

Recruitment Flow Chart

Figure 2

Weight (kg), fat and fat-free soft tissue at baseline, the end of the weight loss intervention (0.5 y) and after 2 years in the Weight Loss Maintenance (WL-M, n= 22) and Weight Loss Gain (WL-R, n=20) groups. Data (Mean ± SEM). * Repeated Measures ANOVA differs between groups, p < 0.05. The only time point that differed between groups was at 2 years for weight and fat (p < 0.001). Values with different letters are significantly different, p < 0.05. Upper and lower case letters are used to denote WL-R and WL-M, respectively.

Figure 3

Bone mineral density (BMD) at baseline, the end of the weight loss intervention (0.5 y) and the follow-up (2 y) in theWeight Loss Maintenance (WL-M, n= 22) and Weight Loss Gain (WL-R, n=20) groups. (Mean ± SEM); * Repeated Measures ANOVA differs between groups, (P < 0.02); † p < 0.08. There are no significant between group differences at any time point. Values with different letters are significantly different. Upper and lower case letters are used to denote WL-R and WL-M, respectively.