Proximal femur mechanical adaptation to weight gain in late adolescence: A six-year longitudinal study

Moira A. Petit, Thomas J. Beck, Julie M. Hughes, Hung Mo Lin, Christy Bentley, Tom Lloyd

Research output: Contribution to journalArticle

49 Citations (Scopus)

Abstract

The effect of weight gain in late adolescence on bone is not clear. Young women who consistently gained weight (n = 23) from 17 to 22 yr of age had increased BMD but a lack of subperiosteal expansion compared with stable weight peers (n = 48). Bone strength increased appropriately for lean mass in both groups but decreased relative to body weight in weight gainers, suggesting increased bone fragility in weight gainers. Introduction: Weight gain leading to obesity often starts in adolescence, yet little is known about its effects on bone. We used longitudinal data to examine the effects of weight gain in late adolescence (from 17 to 22 yr of age) on proximal femur BMD, geometry, and estimates of bending strength. Materials and Methods: Participants were classified as either weight gainers (WG, n = 23) or stable weight (SW, n = 48) using a random coefficients model. Weight gainers had positive increases in weight (p < 0.05) at each clinic visit from age 17 onward. Proximal femur DXA scans (Hologic QDR 2000) taken annually from 17 to 22 yr of age were analyzed for areal BMD (g/cm2), subperiosteal width (cm), and bone cross-sectional area (CSA) at the proximal femoral shaft. Cortical thickness was measured, and section modulus (Z, cm3) was calculated as a measure of bone bending strength. Total body lean (g) and fat (g) mass were measured from DXA total body scans. Results: Over ages 17-22, height remained stable in both groups. Weight remained static in the SW group but increased 14% on average in the WG group (p < 0.05). After controlling for age 17 baseline values, WG had higher BMD (+2.6%), thicker cortices (+3.6%), and greater bone CSA (+2.3%). Increased BMD did not translate to greater increases in bone bending strength (Z). The SW group achieved similar gains in Z by greater subperiosteal expansion. Bone strength index (SI = Z/height) normalized for body weight remained constant in the SW group but decreased significantly in the WG group. In contrast, SI normalized to lean mass did not change over time in either group. Other variables including physical activity, nutrition, and hormone levels (estradiol, testosterone, cortisol) did not differ significantly between groups. Conclusions: These data suggest that weight gain in late adolescence may inhibit the periosteal expansion known to normally occur throughout life in long bones, resulting in decreased bone strength relative to body weight.

Original languageEnglish (US)
Pages (from-to)180-188
Number of pages9
JournalJournal of Bone and Mineral Research
Volume23
Issue number2
DOIs
StatePublished - Feb 1 2008

Fingerprint

Femur
Weight Gain
Longitudinal Studies
Bone and Bones
Weights and Measures
Body Weight
Photon Absorptiometry
Ambulatory Care
Thigh
Hydrocortisone
Testosterone
Estradiol
Obesity
Fats
Hormones
Exercise

All Science Journal Classification (ASJC) codes

  • Endocrinology, Diabetes and Metabolism
  • Orthopedics and Sports Medicine

Cite this

Petit, Moira A. ; Beck, Thomas J. ; Hughes, Julie M. ; Lin, Hung Mo ; Bentley, Christy ; Lloyd, Tom. / Proximal femur mechanical adaptation to weight gain in late adolescence : A six-year longitudinal study. In: Journal of Bone and Mineral Research. 2008 ; Vol. 23, No. 2. pp. 180-188.
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abstract = "The effect of weight gain in late adolescence on bone is not clear. Young women who consistently gained weight (n = 23) from 17 to 22 yr of age had increased BMD but a lack of subperiosteal expansion compared with stable weight peers (n = 48). Bone strength increased appropriately for lean mass in both groups but decreased relative to body weight in weight gainers, suggesting increased bone fragility in weight gainers. Introduction: Weight gain leading to obesity often starts in adolescence, yet little is known about its effects on bone. We used longitudinal data to examine the effects of weight gain in late adolescence (from 17 to 22 yr of age) on proximal femur BMD, geometry, and estimates of bending strength. Materials and Methods: Participants were classified as either weight gainers (WG, n = 23) or stable weight (SW, n = 48) using a random coefficients model. Weight gainers had positive increases in weight (p < 0.05) at each clinic visit from age 17 onward. Proximal femur DXA scans (Hologic QDR 2000) taken annually from 17 to 22 yr of age were analyzed for areal BMD (g/cm2), subperiosteal width (cm), and bone cross-sectional area (CSA) at the proximal femoral shaft. Cortical thickness was measured, and section modulus (Z, cm3) was calculated as a measure of bone bending strength. Total body lean (g) and fat (g) mass were measured from DXA total body scans. Results: Over ages 17-22, height remained stable in both groups. Weight remained static in the SW group but increased 14{\%} on average in the WG group (p < 0.05). After controlling for age 17 baseline values, WG had higher BMD (+2.6{\%}), thicker cortices (+3.6{\%}), and greater bone CSA (+2.3{\%}). Increased BMD did not translate to greater increases in bone bending strength (Z). The SW group achieved similar gains in Z by greater subperiosteal expansion. Bone strength index (SI = Z/height) normalized for body weight remained constant in the SW group but decreased significantly in the WG group. In contrast, SI normalized to lean mass did not change over time in either group. Other variables including physical activity, nutrition, and hormone levels (estradiol, testosterone, cortisol) did not differ significantly between groups. Conclusions: These data suggest that weight gain in late adolescence may inhibit the periosteal expansion known to normally occur throughout life in long bones, resulting in decreased bone strength relative to body weight.",
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Proximal femur mechanical adaptation to weight gain in late adolescence : A six-year longitudinal study. / Petit, Moira A.; Beck, Thomas J.; Hughes, Julie M.; Lin, Hung Mo; Bentley, Christy; Lloyd, Tom.

In: Journal of Bone and Mineral Research, Vol. 23, No. 2, 01.02.2008, p. 180-188.

Research output: Contribution to journalArticle

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T1 - Proximal femur mechanical adaptation to weight gain in late adolescence

T2 - A six-year longitudinal study

AU - Petit, Moira A.

AU - Beck, Thomas J.

AU - Hughes, Julie M.

AU - Lin, Hung Mo

AU - Bentley, Christy

AU - Lloyd, Tom

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