title: Micronutrient deficiency in obese subjects undergoing low calorie diet Premenopausal overweight women do not lose bone during moderate weight loss with adequate or higher calcium intake. Influence of moderate energy restriction and seafood consumption on bone turnover in overweight young adults. Cross-sectional and prospective cohort study of serum 25-hydroxyvitamin D level and obesity in adults: the HUNT study. Dairy calcium intake, serum vitamin D, and successful weight loss. Rising serum 25-hydroxy-vitamin D levels after weight loss in obese women correlate with improvement in insulin resistance. Dairy Foods in a Moderate Energy Restricted Diet Do Not Enhance Central Fat, Weight, and Intra-Abdominal Adipose Tissue Losses nor Reduce Adipocyte Size or Inflammatory Markers in Overweight and Obese Adults: A Controlled Feeding Study Low-Dose Vitamin D Prevents Muscular Atrophy and Reduces Falls and Hip Fractures in Women after Stroke: A Randomized Controlled Trial Influence of Calcium and Vitamin D Supplementation on Weight and Fat Loss in Obese Women Increased Consumption of Dairy Foods and Protein during Diet- and Exercise-Induced Weight Loss Promotes Fat Mass Loss and Lean Mass Gain in Overweight and Obese Premenopausal Women1234 Calcium supplementation suppresses bone turnover during weight reduction in postmenopausal women. Vitamin D status modification by two slightly hypocaloric diets in young overweight/obese women. Bone minerals changes in obese women during a moderate weight loss with and without calcium supplementation. Effects of weight loss on serum vitamin D in postmenopausal women.
abstract: Background The prevalence of micronutrient deficiencies is higher in obese individuals compared to normal-weight people , probably because of inadequate eating habits but also due to increased dem and s among overweight persons , which are underestimated by dietary reference intakes ( DRI ) intended for the general population . We therefore evaluated the dietary micronutrient intake in obese individuals compared to a reference population and DRI recommendations . Furthermore , we determined the micronutrient status in obese subjects undergoing a st and ardized DRI-covering low-calorie formula diet  to analyze if the DRI meet the micronutrient requirements of obese individuals . Methods In 104 subjects baseline micronutrient intake was determined by dietary record collection .  A r and omly assigned subgroup of subjects ( n = 32 ) underwent a st and ardized DRI-covering low-calorie formula diet over a period of three months . Pre- and post-interventional intracellular micronutrient status in buccal mucosa cells ( BMC ) was analyzed , as well as additional micronutrient serum concentrations in 14 of the subjects . Results Prior to dietetic intervention , nutrition was calorie-rich and micronutrient-poor . Baseline deficiencies in serum concentrations were observed for 25-hydroxyvitamin-D , vitamin C , selenium , iron , as well as ß-carotene , vitamin C , and lycopene in BMC . After a three-month period of formula diet even more subjects had reduced micronutrient levels of vitamin C ( serum , BMC ) , zinc , and lycopene . There was a significant negative correlation between lipophilic serum vitamin concentrations and body fat , as well as between iron and C-reactive protein . Conclusions The present pilot study shows that micronutrient deficiency occurring in obese individuals is not corrected by protein-rich formula diet containing vitamins and minerals according to DRI . In contrast , micronutrient levels remain low or become even lower , which might be explained by insufficient intake , increased dem and and unbalanced dispersal of lipophilic compounds in the body . Trial registration The study was registered at Clinical Trials.gov ( NCT01344525 ) . The study protocol comprises only a part of the approved trial protocol BACKGROUND Weight loss is associated with bone loss , but this has not been examined in overweight premenopausal women . OBJECTIVE The aim of this study was to assess whether overweight premenopausal women lose bone with moderate weight loss at recommended or higher than recommended calcium intakes . DESIGN Overweight premenopausal women [ n = 44 ; x ( + /-SD ) age : 38 + /- 6.4 y ; body mass index ( BMI ): 27.7 + /- 2.1 kg/m(2 ) ] were r and omly assigned to either a normal ( 1 g/d ) or high ( 1.8 g/d ) calcium intake during 6 mo of energy restriction [ weight loss ( WL ) groups ] or were recruited for weight maintenance at 1 g Ca/d intake .  Regional bone mineral density and content were measured by dual-energy X-ray absorptiometry , and markers of bone turnover were measured before and after weight loss . True fractional calcium absorption ( TFCA ) was measured at baseline and during caloric restriction by using a dual-stable calcium isotope method . RESULTS The WL groups lost 7.2 + /- 3.3 % of initial body weight . No significant decrease in BMD or rise in bone turnover was observed with weight loss at normal or high calcium intake . The group that consumed high calcium showed a strong relation ( r = 0.71 ) between increased femoral neck bone mineral density and increased serum 25-hydroxyvitamin D. No significant effect of weight loss on TFCA was observed , and the total calcium absorbed was adequate at 238 + /- 81 and 310 + /- 91 mg/d for the normal- and high-calcium WL groups , respectively . CONCLUSION Overweight premenopausal women do not lose bone during weight loss at the recommended calcium intake , which may be explained by sufficient amounts of absorbed calcium BACKGROUND Overweight and obesity are increasing in young adults . However , moderate energy restriction aim ed at lowering body weight may promote bone turnover and bone loss . Inclusion of fish or fish oils in a weight-loss diet may attenuate these adverse skeletal effects . OBJECTIVE We examined the effects of incorporating fish or fish oil into an energy-restricted diet on bone turnover markers in young overweight adults . DESIGN While following a strict hypoenergetic ( -30 % relative to estimated requirements ) diet for 8 wk , 276 overweight men and women [ body mass index ( in kg/m(2 ) ) : 27.5 - 32.5 ; age : 20 - 40 y ) were r and omly assigned to 1 of 4 dietary groups : sunflower-oil capsules ( 3 g/d ; control ) , cod ( 3 x 150 g/wk ) , salmon ( 3 x 150 g/wk ) , and fish-oil capsules ( 3 g/d ) . Body weight , bone biomarkers , and 25-hydroxyvitamin D were measured at baseline and endpoint . Data were analyzed with repeated- measures analysis of variance and general linear models . RESULTS The mean ( + /-SD ) weight loss was 5.14 + /- 3.0 kg ( 5.8 % + /- 3.2 % body weight ) during the 8 wk in the 4 dietary groups combined . Urinary N-telopeptides of type I collagen and serum C-terminal telopeptide of type I collagen increased ( P < 0.05 ) , whereas serum osteocalcin ( but not bone-specific alkaline phosphatase ) decreased ( P < 0.05 ) from baseline to endpoint . Increased fish or fish-oil consumption had no effect ( P > 0.1 ) on the changes in bone markers induced by weight loss . In contrast , increased salmon consumption increased serum 25-hydroxyvitamin D ( P < 0.01 ) . CONCLUSIONS A nutritionally adequate but energy-restricted diet , with different contents of n-3 fatty acids , which result ed in modest weight loss , unfavorably altered bone turnover markers  in young overweight adults . Such changes were not prevented by increased fish or fish-oil consumption Experimental studies suggest that vitamin D modulates the activity of adipocytes . The authors examined baseline serum 25-hydroxyvitamin D ( 25(OH)D )  level in relation to prevalent and cumulative incident obesity in Norway . A cohort of 25,616 adults aged 19 - 55 years participated in both the second and third surveys of the Nord-Trøndelag Health Study ( HUNT 2 ( 1995 - 1997 ) and HUNT 3 ( 2006 - 2008 ) ) .  Serum 25(OH)D levels measured at baseline and  anthropometric measurements  taken at both baseline and follow-up were available for a r and om sample of 2,460 subjects . Overall , 40 % of the 2,460 subjects had a serum 25(OH)D level less than 50.0 nmol/L , and 37 % had a level of 50.0 - 74.9 nmol/L. The prevalence and cumulative incidence of obesity , defined as body mass index ( weight (kg)/height (m)(2 ) ) ≥30 , were 12 % and 15 % , respectively . Lower serum 25(OH)D level was associated with a higher prevalence of obesity . In the 2,165 subjects with baseline BMI less than 30 , a serum 25(OH)D level less than 50.0 nmol/L was associated with a significantly increased odds ratio for incident obesity during follow-up ( adjusted odds ratio = 1.73 , 95 % confidence interval : 1.24 , 2.41 ) . When prevalent and incident obesity were classified according to waist circumference ( ≥88 cm for women , ≥102 cm for men ) , similar results were obtained . In addition to prevalent obesity , a serum 25(OH)D level less than 50.0 nmol/L was significantly associated with new-onset obesity in adults BACKGROUND The role of dairy calcium intake and serum vitamin D concentrations in weight loss is controversial . OBJECTIVE The objective was to assess the association of dairy calcium intake and serum vitamin D with weight loss . DESIGN We analyzed data from participants in the 2-y Dietary Intervention R and omized Controlled Trial ( DIRECT ) [ n = 322 ; mean body mass index ( BMI ; in kg/m² ) : 31 ; mean age : 52 y ] . A representative sample ( n = 126 ) was followed for 6 mo for serum vitamin D changes . RESULTS Baseline serum 25-hydroxyvitamin D [ 25(OH)D ] concentrations decreased significantly across the tertiles of baseline BMI ( 25.6 ± 8.0 , 24.1 ± 8.9 , and 22.9 ± 6.8 ng/mL , respectively ; P for trend = 0.02 ) . Baseline concentrations of vitamin D and dairy calcium  intake were not associated with subsequent weight loss . However , in repeated- measures models adjusted for age , sex , baseline BMI , total fat intake , and diet group assignment , higher 6-mo tertile levels of dairy calcium intake ( median for tertiles : 156.5 , 358.0 , and 582.9 mg/d , respectively ) and serum 25(OH)D ( 14.5 , 21.2 , and 30.2 ng/mL , respectively ) were associated with increased weight loss across the 2-y intervention ( -3.3 , -3.5 , and -5.3 kg , respectively , for dairy calcium ; P = 0.043 ; -3.1 , -3.8 , and -5.6 kg , respectively , for vitamin D ; P = 0.013 ) . In a multivariate logistic regression adjusted simultaneously for age , sex , baseline BMI , total fat intake , diet group , vitamin D concentration , and dairy calcium , an increase of 1 SD in  dairy calcium intake increased the likelihood of weight loss of > 4.5 kg in the preceding 6 mo [ odds ratio ( OR ) : 1.45 ; P = 0.046 ] . A similar increase was seen for serum 25(OH)D at the 6-mo point ( OR : 1.7 ; P = 0.009 ) . CONCLUSION Our study suggests that both higher dairy calcium intake and increased serum vitamin D are related to greater diet-induced weight loss . This trial was registered at clinical trials.gov as NCT00160108 OBJECTIVE The objective of the study was to examine changes of 25-hydroxy-vitamin D ( 25OHD ) and PTH blood levels 4 and 20 wk after low-calorie diet-induced weight loss . METHODS Forty-four obese women [ aged 40.6 + /- 11.4 yr , body mass index ( BMI ) 36.7 + /- 4.9 kg/m(2 ) ] and 25 controls ( BMI 22.9 + /- 1.5 kg/m(2 ) ) were examined .  Anthropometric and cardiometabolic parameters and 25OHD and PTH levels  were determined at baseline and 4 and 20 wk after a low-calorie diet . RESULTS At baseline , 25OHD levels were lower in obese compared with control subjects ( 17 + /- 6.0 vs. 23.8 + /- 8.7 ng/ml , P < 0.001 ) , whereas no differences were found in PTH levels . In all women , a negative correlation was found between 25OHD levels and body weight ( BW ) ( r -0.32 , P < 0.001 ) , BMI ( r -0.37 , P < 0.001 ) , waist circumference ( r -0.26 , P < 0.05 ) , and percent fat mass ( r -0.38 , P = 0.001 ) as determined by bioelectrical impedance analysis . The 4-wk low-calorie diet ( n = 37 ) reduced BW and led to significant improvements in the homeostasis model assessment ( HOMA ) index and lipid levels . The 20-wk low-calorie diet ( n = 26 ) result ed in reduction of BW and BMI by 10 % , HOMA index ( 4.7 + /- 3.8 vs. 3.10 + /- 1.7 , P < 0.01 ) , and lipids levels ( except high density lipoprotein cholesterol ) and increase in 25OHD ( 15.4 + /- 6.0 vs. 18.3 + /- 5.1 ng/ml , P < 0.05 ) , compared with baseline . PTH levels were unchanged . The increase of 25OHD levels was associated with the reduction of insulin levels and HOMA index ( r -0.43 , P < 0.05 ) . CONCLUSIONS Blood 25OHD levels were low in obese women and correlated inversely with severity measures of obesity . Weight loss of 10 % after low-calorie diet increased 25OHD levels , and this increase was mainly associated with improvement of insulin resistance Background . Research on dairy foods to enhance weight and fat loss when incorporated into a modest weight loss diet has had mixed results . Objective . A 15-week controlled feeding study to determine if dairy foods enhance central fat and weight loss when incorporated in a modest energy restricted diet of overweight and obese adults . Design . A 3-week run-in to establish energy needs ; a 12-week 500 kcal/d energy reduction with 71 low-dairy-consuming overweight and obese adults r and omly assigned to diets : ≤1 serving dairy/d ( low dairy , LD ) or ≤4 servings dairy/d ( adequate dairy , AD ) . All foods were weighed and provided by the metabolic kitchen . Weight , fat , intra-abdominal adipose tissue ( IAAT ) , subcutaneous adipose tissue ( SAT ) macrophage number , SAT inflammatory gene expression , and circulating cytokines were measured . Results . No diet differences were observed in weight , fat , or IAAT loss ; nor SAT mRNA expression of inflammation , circulating cytokines , fasting lipids , glucose , or insulin . There was a significant increase ( P = 0.02 ) in serum 25-hydroxyvitamin D in the AD group . Conclusion . Whether increased dairy intake during weight loss results in greater weight and fat loss for individuals with metabolic syndrome deserves investigation . Assessment of appetite , hunger , and satiety with followup on weight regain should be considered OBJECTIVE Vitamin D supplementation is suggested to reduce the risk of falls among ambulatory or institutionalized elderly subjects . The present study was undertaken to address the reduced risk of falls and hip fractures in patients with long-st and ing stroke by vitamin D supplementation . METHODS Ninety-six elderly women with poststroke hemiplegia were followed for two years . Patients were r and omly assigned to one of the two groups , and 48 patients received 1,000 IU ergocalciferol daily , and the remaining 48 received placebo . The number of falls per person and incidence of hip fractures were compared between the two groups . Strength and tissue ATPase of skeletal muscles on the nonparetic side were assessed before and after the study . RESULTS At baseline , serum 25-hydroxyvitamin D levels were in the deficient range ( < 10 ng/ml ) in all patients ; and vitamin D treatment enhanced serum 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D levels .  Vitamin D treatment accounted for a 59 % reduction in falls ( 95 % CI , 28 - 81 % ; p = 0.003 ) . There were increases in the relative number and size of type II muscle fibers and improved muscle strength in the vitamin D-treated group . Hip fractures occurred in 4 of 48 placebo group and 0 in 48 vitamin D2 group during the 2-year study period ( log-rank , p = 0.049 ) . CONCLUSION Vitamin D may increase muscle strength by improving atrophy of type II muscle fibers , which may lead to decreased falls and hip fractures Background : Dairy products not only reduce the risk of hypertension and cardiovascular diseases but may play a role in the treatment of obesity . As there is some evidence that calcium ( Ca ) and vitamin D may play a role in effective weight management , we decided to evaluate the influence of Ca and vitamin D supplementation on weight and fat loss  in obese women . Material and Methods : Forty obese women were enrolled in this study . Subjects were divided into 2 groups comparable with body mass index ( BMI ) and age . Group 1 was provided with calcium carbonate and 1-(OH)-vitamin D supplementation . Group 2 was provided with only a diet . Subjects participated in a 3-month weight reduction therapy ( balanced diet , modification of life style , and regular physical exercise ) . Blood sample s ( serum concentration of Ca , phosphorus ( P ) , parathormone ( PTH ) , 25-(OH)-D3 ) and clinical characteristics ( weight , height , BMI , body composition ) were taken at baseline and after the 3-month program . Results : No significant differences of body weight , body fat content , serum parathormone , 25-(OH)-D3 concentration , and plasma total Ca and P concentration were observed between analyzed groups both before and after the treatment . Additionally , we did not observe any significant influence of Ca and vitamin D supplementation on weight and fat loss . Conclusion : Ca plus vitamin D supplementation during a 3-month low caloric diet has no additional effect on weight and fat loss in obese women Weight loss can have substantial health benefits for overweight or obese persons ; however , the ratio of fat : lean tissue loss may be more important . We aim ed to determine how daily exercise ( resistance and /or aerobic ) and a hypoenergetic diet varying in protein and calcium content from dairy foods would affect the composition of weight lost in otherwise healthy , premenopausal , overweight , and obese women . Ninety participants were r and omized to 3 groups ( n = 30/group ) : high protein , high dairy ( HPHD ) , adequate protein , medium dairy ( APMD ) , and adequate protein , low dairy ( APLD ) differing in the quantity of total dietary protein and dairy food- source protein consumed : 30 and 15 % , 15 and 7.5 % , or 15 and < 2 % of energy , respectively . Body composition was measured by DXA at 0 , 8 , and 16 wk and MRI ( n = 39 ) to assess visceral adipose tissue ( VAT ) volume at 0 and 16 wk . All groups lost body weight ( P < 0.05 ) and fat ( P < 0.01 ) ; however , fat loss during wk 8–16 was greater in the HPHD group than in the APMD and APLD groups ( P < 0.05 ) . The HPHD group gained lean tissue with a greater increase during 8–16 wk than the APMD group , which maintained lean mass and the APLD group , which lost lean mass ( P < 0.05 ) . The HPHD group also lost more VAT as assessed by MRI ( P < 0.05 ) and trunk fat as assessed by DXA ( P < 0.005 ) than the APLD group . The reduction in VAT in all groups was correlated with intakes of calcium ( r = 0.40 ; P < 0.05 ) and protein ( r = 0.32 ; P < 0.05 ) . Therefore , diet- and exercise-induced weight loss with higher protein and increased dairy product intakes promotes more favorable body composition changes in women characterized by greater total and visceral fat loss and lean mass gain Bone mobilization , lowering of bone mineral density ( BMD ) , and osteoporotic fractures are recognized in postmenopausal women with weight loss . Because a high-calcium intake suppresses bone loss in peri- and postmenopausal women , the present r and omized , double-blind , placebo-controlled study was design ed to test the hypothesis that calcium supplementation prevents net bone mobilization and consequent bone mineral loss during voluntary weight reduction in obese postmenopausal women . Subjects were placed on a moderate energy-restricted diet and either calcium supplementation ( 1 g/day ) or placebo for 6 months . Body weight , bone turnover markers ( pyridinium cross-links ) , osteocalcin , and parathyroid hormone ( PTH ) were measured at treatment weeks 1 - 5 , 7 , 10 , 13 , 16 , 20 , and 25 . Total body BMD , insulin-like growth factor , 25-hydroxyvitamin D , and sex hormone binding globulin ( SHBG ) were measured at baseline and week 25 . The calcium supplemented ( n = 15 ; age 60.9 + /- 9.4 years , body mass index [ BMI ] 33.2 + /- 4.6 kg/m2 ) and placebo ( n = 16 ; age 55.8 + /- 8.3 years , BMI 32.9 + /- 4.5 kg/m2 ) groups lost similar amounts of weight over the study interval ( 10.2 + /- 5.3 % vs. 10.0 + /- 5.2 % ) and both groups increased SHBG ( p < 0.001 ) . There was a statistical effect of calcium supplementation during weight loss to suppress pyridinium cross-links , osteocalcin , and PTH ( p < 0.05 , < 0.01 , and < 0.05 , respectively ) . Loss of BMD tended to be greater in the placebo group by 1.4 % ( p < 0.08 ) after weight loss . One gram per day calcium supplementation normalizes the increased calcium-PTH axis activity and the elevated bone turnover rate observed during moderate voluntary energy restriction in postmenopausal women Obesity has been linked with poorer vitamin D status . The aim of this work was to analyze the changes in vitamin D status and body weight of 61 young , overweight/obese women following two different weight control programs . The study subjects were r and omly assigned to one of two slightly hypocaloric diets : diet V , in which the consumption of greens and vegetables was increased , or diet C , in which the consumption of cereals ( some of which were enriched with vitamin D ) was increased .  Dietary , anthropometric , and biochemical data were collected at the start of the study and at 2 weeks . At the beginning of the study , when taking into account only those women with a vitamin D intake below that recommended , obese women had a significantly lower mean serum 25(OH)D concentration than those who were lighter . Dietary intervention led to a greater reduction in energy intake among group C subjects ; their weight was also that which was most reduced . In addition , the vitamin D intake and serum 25(OH)D values were increased only in group C women . Excess body weight was associated with deterioration in vitamin D status , especially when the intake of this vitamin was lower than that recommended . Subjects with higher serum vitamin D at the beginning of the study lost more weight than those subjects with lower initial values . Diet C was associated with a greater weight loss than diet V , and led to a greater increase in vitamin D intake and serum 25(OH)D levels . This might be of interest in the improvement of health in people trying to lose weight A significant relationship between body weight ( BW ) and bone mass ( BM ) has been established previously . A diet-induced weight loss is accompanied by a significant decrease in bone mineral density ( BMD ) and total body bone mineral ( TBBM ) , but the underlying mechanisms are not clarified . Sixty-two obese women were included in the study .  Dual-energy X-ray absorptiometry ( DXA ) and measurements of a series of calcium-regulating hormones and biochemical markers of bone turnover were performed at baseline and after 1 month and 3 months on a low calorie diet . Thirty of the women were r and omized to a daily supplement of 1 g of calcium . After an additional 3 months without dietary prescriptions or calcium supplements , a subgroup of 48 subjects ( 24 from each group ) were scanned again using DXA . There was a significant decrease in TBBM after 1 month and 3 months . A similar pattern was observed in the bone mineral content ( BMC ) of the lumbar spine in the patients who did not receive a calcium supplement , whereas no changes occurred in the supplemented group . The initial calcium supplementation seemed to protect against bone loss in the lumbar spine but not in the TBBM . In the nonsupplemented group , a statistically significant inverse correlation was found between the calcium/creatinine ratio in the morning urine and the changes in BMC of the lumbar spine . Such a relationship was not seen in the calcium-supplemented group . In the nonsupplemented group , no significant biochemical changes were observed , whereas a significant decrease in serum parathyroid hormone ( PTH ) was seen in the calcium-supplemented group . This might explain some of the protective effects of calcium supplementation on trabecular bone mass . We conclude that a diet-induced weight loss is accompanied by a generalized bone loss , which probably is explained mainly by a reduced mechanical strain on the skeleton . This loss can be partly inhibited by a high calcium intake . Therefore , a calcium supplementation should be recommended during weight loss , even if the diet contains the officially recommended amounts of calcium BACKGROUND Low concentrations of circulating vitamin D are common with obesity and may represent a potential mechanism explaining the elevated risk of certain cancers and cardiovascular outcomes observed in individuals who are overweight or obese . OBJECTIVE The objective of this study was to investigate the effects of 12 mo of weight loss through caloric restriction , exercise intervention , or both on serum 25-hydroxyvitamin D [ 25(OH)D ] concentrations . DESIGN Overweight and obese postmenopausal women ( n = 439 ) were r and omly assigned to 1 of 4 groups : 1 ) diet modification ( n = 118 ) , 2 ) exercise ( n = 117 ) , 3 ) diet + exercise ( n = 117 ) , or 4 ) control ( n = 87 ) . The diet intervention was a group-based reduced-calorie program with a 10 % weight-loss goal . The exercise intervention consisted of 45 min of moderate-to-vigorous intensity aerobic activity daily for 5 d/wk . Serum 25(OH)D concentrations were measured by using a competitive chemiluminescent immunoassay at baseline and 12 mo . RESULTS No significant change in serum 25(OH)D was found between the intervention and control groups . Women who lost < 5 % , 5 - 9.9 % , 10 - 14.9 % , or ≥15 % of baseline weight had mean increases in 25(OH)D of 2.1 , 2.7 , 3.3 , and 7.7 ng/mL , respectively ( P for trend = 0.002 ) . Baseline vitamin D status did not modify the effect of the interventions on weight loss or body-composition changes at the 12-mo follow-up . CONCLUSION A greater degree of weight loss , achieved through either a reduced-calorie diet or increased exercise , is associated with increased circulating 25(OH)D concentrations . This trial is registered at clinical trials.gov as NCT00470119
target: Collectively , these outcomes support a volumetric dilution of vitamin D. The slopes of the respective regression lines , however , indicate a smaller increase in 25OHD than would be expected from a direct mobilization of stores into the circulation .
  Hence , sequestration of 25OHD and its conversion to inactive metabolites would also play a role .
background: The purpose of this review was to confirm a volumetric dilution of vitamin D in obesity .
  It was based on the hypothesis that weight loss , particularly fat loss , would increase serum 25-hydroxyvitamin D ( 25OHD ) in the obese .