Leptin may play a role in bone microstructural alterations in obese children.

Bone mass is low and fracture risk is higher in obese children. Hormonal changes in relation to skeletal microstructure and biomechanics have not been studied in obese children

The Adibox Study: Adiposity and Bone Metabolism: Effects of Exercise-induced Weight Loss in Adolescents with Obesity

Introduction: This program of research targeted the impact of an 8-month weight loss intervention induced by physical activity and nutrition on bone health in adolescents with obesity. The overall aim of this thesis was to examine the impact of a lifestyle weight loss intervention on the bone parameters in adolescents with obesity. Method: Sixty-five adolescents were recruited: 31 (6 males) adolescents with obesity in the weight loss intervention (age: 13.61 (1.27)), 23 normal weight (NW) adolescents (age: 15.90 (0.43)) and 11 (4 males) adolescents with obesity in another control group (14.02 (1.39)). Primary outcomes targeted bone densitometry (whole body, spine, hip DXA). Secondary outcomes included body composition, bone geometry and strength (hip structural analysis) and bone biomarkers (procollagen type 1 N-terminal propeptide (P1NP), C telopeptide (CTx) estradiol, leptin). Data were collected at baseline, 4 months and 8 months. Data were adjusted for body weight, fat mass and lean mass changes. Results: Compared with the NW controls, adolescents with obesity displayed lower unadjusted and adjusted bone density. Following successful weight loss (~ -11%) adolescents with obesity increased whole body (%Ob Δ 3.22 (3.58) pp<0.001) and lumbar spine (%Ob Δ 6.27 (12.45) p=0.014) BMD. However, values remain lower than their NW peers after adjustment to body weight changes. After the weight loss intervention, compromised estimates of fracture risk remained especially at the narrow neck (buckling ratio (BR) 8.25 (2.00) p=0.005), despite positive adaptations of some geometric properties (i.e. NN CSA, NN Z). Also, bone accretion changes in adolescents with obesity followed an androgen-like adaptation demonstrated by periosteal expansion (% NW Δ 0.69 (3.71); Ob Δ 1.67 (9.11)) and endocortical resorption (% NW Δ -2.11 (11.79); Ob Δ 4.42 (10.56)). Among the intervention group, differences in bone markers favoured formation during the first 4 months and favoured resorption in the remaining months. Conclusion: Bone fragility in adolescents with obesity was demonstrated by (1) baseline and post intervention lower whole body and regional BMD than NW controls, (2) post-intervention higher fracture risk index at the narrow neck, (3) bone biomarkers showing reduced z-scores, uncoupling indices and qualitative representations of the distribution of bone remodeling. Future investigations of links between bone and obesity during adolescence can be well informed by the results of this thesis

Effects of obesity and resistance exercise on bone health studied with modern imaging methods

Altered metabolic states, such as obesity and resistance exercise, may affect bone health either in a negative or positive manner. In clinical practice, bone health may be easily understood as a synonym for bone mineral density or osteoporosis, which is defined as a skeletal disorder resulting from decreased bone strength. In addition, bone glucose metabolism and bone marrow adiposity may contribute to bone overall health status. The aims of this thesis were to investigate the effects of obesity and resistance exercise on bone glucose metabolism, bone marrow adiposity and bone mineral density using modern imaging methods, such as positron emission tomography, magnetic resonance imaging and quantitative computed tomography, in various study settings. It was found that obesity did not alter bone glucose metabolism or bone marrow adiposity. However, resistance exercise resulted in improved bone glucose metabolism and bone mineral density. In conclusion, resistance exercise, but not obesity, had an impact on bone health studied with modern imaging methods. The obtained results may offer new insights into quantification and into the follow-up of bone health during altered metabolic conditions. In addition, more individualized and accurately allocated lifestyle interventions may be administered in the treatment or prevention of diseases associated with obesity or insulin resistance.Ylipainon ja lihasvoimaharjoittelun vaikutus luun terveyteen tutkittuna modernien kuvantamismenetelmien avulla Aineenvaihduntaa muuntelevat fysiologiset tilat kuten lihavuus ja lihasvoimaharjoittelu voivat mahdollisesti vaikuttaa luun terveyteen joko negatiivisesti tai positiivisesti. Luun terveys kuitenkin ymmärretään usein vain synonyymina luuntiheydelle tai osteoporoosille, joka on luun alentuneesta lujuudesta johtuva sairaus. Luun terveyteen voi kuitenkin olla osallisena muitakin vähemmän tunnettuja potentiaalisia tekijöitä kuten luun sokeriaineenvaihdunta ja luuytimen rasvoittuminen. Väitöskirjan tarkoituksena oli tutkia lihavuuden ja lihasvoimaharjoittelun vaikutuksia luun sokeriaineenvaihduntaan, luuytimen rasvoittumiseen sekä luuntiheyteen modernien kuvantamismenetelmien kuten positroniemissiotomografian, magneettikuvauksen ja kvantitatiivisen tietokonetomografian avulla erilaisissa tutkimusasetelmissa. Tulosten mukaan lihavuudella ei ollut vaikutusta luun sokeriaineenvaihduntaan tai luuytimen rasvoittumiseen. Sen sijaan lihasvoimaharjoittelu näytti parantavan luun sokeriaineenvaihduntaa ja luuntiheyttä. Yhteenvetona voidaan siis todeta, että lihasvoimaharjoittelulla on positiivinen vaikutus luun terveyteen modernien kuvantamismenetelmien avulla tutkittuna. Sen sijaan lihavuudella ei ole siihen vaikutusta. Väitöskirjatutkimuksen tulokset voivat tuottaa uusia oivalluksia aineenvaihdunnallisiin häiriötiloihin liittyvässä luun terveyden määrittämisessä ja seurannassa. Lisäksi tuloksia soveltaen voidaan suunnitella aiempaa yksilöllisempiä ja kohdistetumpia elämäntapainterventioita lihavuuteen ja insuliiniresistenssiin liittyvien luun häiriötilojen ehkäisyssä ja hoidossa.Siirretty Doriast