The Changes of Body Composition, Glucolipid Metabolism and Bone Metabolism in Obese Children After Weight Loss
Condition: Obesity, Childhood; Vitamin D Deficiency
MeSH terms: Vitamin D Deficiency; Pediatric Obesity; Weight Loss
Study type: Interventional

Summary: 
      Vitamin D plays a significant role in calcium and phosphorus homeostasis for maintaining
      structural integrity and function of musculoskeletal system. Furthermore, recent studies have
      revealed that vitamin D can decrease the risk of many conditions other than skeletal disease,
      including autoimmune diseases, cancers, obesity and obesity-related diseases, such as type 2
      diabetes and cardiovascular disease. Vitamin D may influence calcium absorption to affect
      obesity indirectly, regulate adipocyte differentiation and relieve the development of
      metabolic syndrome by mediating levels of inflammatory factors.

      Another indicator of bone metabolism-osteocalcin may also be involved in energy metabolism
      and glucose metabolism, and undercarboxylated osteocalcin (ucOC) is the form which has
      physiological activity. ucOC may recombine with the receptors on the surface of pancreas β
      cells, adipocytes, hepatocytes and intestinal endocrine cell to regulate insulin secretion
      and insulin sensitivity.

      Currently, the prevalence of vitamin D deficiency is a global problem in all age groups
      currently, even in countries with sun exposure all year around. The obesity group tend to
      have a higher incidence of vitamin D deficiency.Moreover, the obesity group tend to have a
      higher incidence of vitamin D deficiency and a lower level of serum osteocalcin.

      This study observed the changes of body composition and glucolipid metabolism and bone
      metabolism during weight loss, and investigated the correlations among them.
    

Detailed description: 
      Obese children have a higher incidence of vitamin D deficiency (VDD), which resulted from
      unhealthy life style such as less time outdoors, more sedentary time, imbalance of dietary
      intake. Adipose tissue is the storage position of vitamin D, and the storage formation
      include 25-OHD2 and 25-OHD3. Theoretically, the reserves of vitamin D in adipose tissue of
      obese children might release to the circulation after weight loss. For further, it is
      necessary to clarify the relationship between the improvement of metabolic risk with vitamin
      D status after weight loss.

      Osteocalcin is produced and secreted by osteoblast specifically. Recent studies have shown
      that it regulated glucose metabolism and energy metabolism. Obese group may have a lower
      level of serum osteocalcin. Both 25-OHD and osteocalcin have association with energy
      metabolism. This study will provide evidence to realize the relationship between bone
      metabolism and obesity.

      In our study, all subjects were recruited from the obese children and adolescents aged 9~17
      years who participated in six-week weight loss camp in July ~ August, 2014. Body mass index
      (BMI) was calculated as weight (kg) divided by height squared (m2). Obesity was defined as
      having a BMI greater than or equal to the 95th percentile for age and sex according to WHO
      standard. Exclusion criteria included: 1) obesity caused by endocrine or heredity diseases
      (eg, hypothyroidism, Prader-Willi syndrome, single-gene defects); 2) any disease influencing
      vitamin D metabolism (eg, such as metabolic bone diseases, rickets, nephritic syndrome and
      hepatic failure); 3) any supplementation use or any medication affecting vitamin D metabolism
      use.

      All subjects underwent a closed-off weight loss program for six weeks. The intervention
      methods included aerobic exercise and appropriate caloric control. The dietary was designed
      on the basis of ensuring the daily energy physiological requirement, and basal metabolic rate
      (BMR) was calculated to formulate diet project according to Harris-Benedict formula. The diet
      was composed of 20% protein, 30% fat and 50% carbohydrates. During the camp, all subjects had
      never taken any kinds of nutritional supplements.

      Before intervention, all subjects received exercise load test to ensure safe and effective
      physical exercise. In the exercise, heart rate was monitored to ensure the small-medial load
      aerobic exercise. The exercise programs included ball games, such as badminton, table tennis,
      and basketball, and also included jogging, brisk walking, swimming and cycle ergometer. All
      kinds of sports were conducted indoor, twice per day, 6 days per week, and lasted for 2 hours
      every time. The weight loss camp was staffed by professional sports coaches and medical
      workers. Exercise intensity was estimated by a formula: exercise intensity (target heart
      rate) =resting heart rate + heart rate reserve (maximum heart rate-resting heart rate) ×
      (20%~40%).

      Before and after intervention, fasting blood samples were collected and sent to Shanghai
      Adicon Central Lab Test Menu immediately stored in 4°C ice packs. The indicators of
      glucolipid metabolism and bone metabolism were tested. Total cholesterol (TC) with
      cholesterol oxidase, triglyceride (TG) with enzyme method (GPO-POD), high density lipoprotein
      (HDL) and low density lipoprotein (LDL) with homogeneous methods, fasting blood glucose (FBG)
      with hexokinase (HK) method, fasting insulin (FINS) with chemiluminescence method. Among the
      indicators of bone metabolism, osteocalcin, parathyroid hormone (PTH) and 25-OHD were assayed
      by electrochemiluminescence immunoassay, while bone specific alkaline phosphatase (BALP),
      total propeptide of type I procollagen (T-PINP) and β-isomerized form carboxy-terminal
      telopeptide of type I collagen (β-CTX) were determined by immunoenzymatic methods.

      After blood samples were collected, anthropometric parameters were measured, including height
      (Seca 264, Germany), weight (Biospace 370, South Korea), triceps skinfold thickness (TST) and
      subscapular skinfold thickness (SST) (skinfold caliper 689900). For error reduction, every
      anthropometric measurement was conducted by the same trained personnels before and after
      weight-loss.
    

Intervention name(s): aerobic exercise and appropriate caloric control
Intervention type(s): Behavioral
Intervention description(s): The dietary was designed on the basis of ensuring the daily energy physiological requirement, and basal metabolic rate (BMR) was calculated to formulate diet project according to Harris-Benedict formula. The diet was composed of 20% protein, 30% fat and 50% carbohydrates.In the exercise, heart rate was monitored to ensure the small-medial load aerobic exercise. All kinds of sports were conducted indoor, twice per day, 6 days per week, and lasted for 2 hours every time.
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Health Services Research
Keywords: vitamin D; obesity; body composition; glucose metabolism; lipid metabolism