BMC Medical Imaging<\/a> found that higher postoperative vitamin D concentrations were associated with less fat infiltration within certain muscles and lower visceral fat in adults with obesity after bariatric surgery. Among patients whose vitamin D concentrations increased, changes in vitamin D were not significantly associated with changes in fat and muscle measurements after correction for multiple comparisons. The researchers also explored the predictive value of preoperative vitamin D for postoperative body composition.<\/p>\nObesity, Bariatric Surgery, and Vitamin D Interplay<\/p>\n
Obesity is a chronic disease marked by excessive fat accumulation, leading to increased risks of type 2 diabetes, cardiovascular disease, and certain cancers. Its rising prevalence continues to strain healthcare systems worldwide.<\/p>\n
For individuals with severe obesity, bariatric surgery, particularly sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB), offers the most effective long-term treatment. These procedures drive significant weight loss and improve body composition by reducing fat mass while aiming to preserve fat-free mass, a key factor in long-term metabolic health.<\/p>\n
Micronutrient deficiencies, especially vitamin D deficiency, are common complications after bariatric surgery. Individuals with obesity often have low vitamin D because of sequestration in fat tissue and limited sunlight exposure. After surgery, anatomical changes, dietary restrictions, and rapid weight loss can exacerbate this deficiency, even with supplementation.<\/p>\n
Vitamin D is integral to musculoskeletal and metabolic health. In muscle, it helps regulate growth and function; in adipose tissue, experimental evidence suggests that vitamin D signaling can influence fat cell formation and lipid storage, especially in visceral fat. Adequate vitamin D status may influence postoperative recovery, but whether it improves muscle or fat outcomes after bariatric surgery remains uncertain.<\/p>\n
Evidence linking vitamin D status to body composition changes after bariatric surgery remains limited and often comes from short-term or cross-sectional studies. More research using advanced imaging is needed to better understand these relationships.<\/p>\n
Measuring Vitamin D Status and Body Composition Before and After Bariatric Surgery<\/p>\n
The current prospective study enrolled 113 adults with obesity scheduled for bariatric surgery at Beijing Friendship Hospital between January 2022 and December 2023. All participants were prescribed standardized supplementation with vitamin D 2000 IU\/day and calcium citrate 600 mg\/day after surgery, along with guidance on healthy lifestyle and diet. Clinical evaluations, laboratory tests, and quantitative computed tomography (QCT) scans were performed before surgery and at the one-year follow-up.<\/p>\n
Relevant data, including age, gender, BMI, surgical details, and blood tests measuring 25-hydroxyvitamin D (25(OH)D), glucose control, and lipids, were collected. Participants were stratified postoperatively into vitamin D deficient (\u226430 ng\/mL) and normal (>30 ng\/mL) groups based on 25(OH)D levels, using the study’s chosen threshold.<\/p>\n
Body composition was assessed using QCT at the L2 vertebra, which measured total, visceral, and subcutaneous fat areas; erector spinae and psoas major muscle areas; and fat infiltration within these muscles. The analysis included absolute tissue areas, height-adjusted fat indices, and muscle fat fractions normalized to muscle size. Radiologists’ measurements showed good reproducibility.<\/p>\n
Exclusion criteria were metabolic bone disease, medications affecting bone metabolism, severe mental illness, and spinal abnormalities.<\/p>\n
![\"Regions](\"https:\/\/www.newsbeep.com\/il\/wp-content\/uploads\/2026\/10\/ImageForNews_849858_17931454582787101.jpg\")
<\/p>\n
Regions of interest (ROIs) for QCT-based body composition analysis at the L2 vertebral level. (A) Quantification of visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) at the L2 vertebral level on QCT images. The ROI is demarcated by the green contour; the blue area within this ROI denotes VAT, while the blue area outside the ROI corresponds to SAT. (B) Quantification of the psoas major muscle (PMM) at the L2 vertebral level on QCT images. The PMM is defined by the green ROI contour, with the yellow area within this contour representing the PMM. (C) Quantification of the erector spinae muscle (ESM) at the L2 vertebral level on QCT images. The ESM is outlined by the green ROI contour, with the yellow area within this contour representing the ESM<\/p>\n
Higher Postoperative Vitamin D Linked to Less Muscle Fat Infiltration and Visceral Adiposity<\/p>\n
A total of 113 patients with obesity (81% female, mean age 33.4 years) underwent bariatric surgery, with a 1-year follow-up. Most underwent sleeve gastrectomy (85 patients), with the remainder undergoing other bariatric procedures.<\/p>\n
After one year, the median body weight fell by 29 kg, body mass index (BMI) decreased by 10.2 kg\/m\u00b2, HbA1c and triglycerides declined, and serum calcium, vitamin D, and high-density lipoprotein cholesterol (HDL-C) increased. Total cholesterol and low-density lipoprotein cholesterol (LDL-C) remained largely unchanged. QCT also showed reductions in erector spinae and psoas major muscle areas, indicating skeletal muscle loss alongside fat loss. Median 25(OH)D rose from approximately 12 to 21 ng\/mL, but most patients remained below the study’s cutoff.<\/p>\n
Patients were categorized based on postoperative vitamin D status: 82 were classified as deficient and 31 as normal. The deficient group had a median 25(OH)D level of approximately 16 ng\/mL, compared to 44 ng\/mL in the normal group. Patients with vitamin D deficiency had greater fat infiltration in the erector spinae and psoas major muscles and higher visceral fat measurements. No significant differences were observed between groups in HbA1c, serum calcium, triglycerides, HDL-C, LDL-C, or other muscle and fat parameters.<\/p>\n
At one year, higher postoperative vitamin D levels were associated with lower muscle fat infiltration and less visceral adiposity in bariatric surgery patients. Among 86 patients whose vitamin D concentrations increased after surgery, changes in vitamin D were not significantly associated with changes in clinical, fat, or muscle measurements after correction for multiple comparisons.<\/p>\n
A sensitivity analysis of patients who underwent sleeve gastrectomy supported these findings, showing that vitamin D deficiency was associated with greater muscle fat infiltration and higher residual visceral fat at follow-up. After adjusting for age, sex, baseline BMI, and surgical procedure, preoperative vitamin D levels were not significantly associated with postoperative body composition.<\/p>\n
Conclusion<\/p>\n
Bariatric surgery can lead to significant weight loss, lower BMI, and improvements in several metabolic indicators, but skeletal muscle area also declined in this cohort. Using the study’s threshold, vitamin D deficiency remained common one year after surgery and was associated with more fat within muscles and around internal organs. The findings support monitoring vitamin D and body composition after surgery, but do not establish that raising vitamin D concentrations improves these outcomes.<\/p>\n
The study has several limitations. The study was conducted at a single center, had a relatively small sample size, and included different types of bariatric procedures. The researchers collected data only before surgery and at one year after, so it is unclear how vitamin D and body composition may change at other times. Adherence to vitamin D supplementation was not closely tracked, so the high rate of deficiency after surgery could reflect missed doses and biological factors. The study was observational, and its postoperative correlations were not adjusted for clinical confounding factors. Parathyroid hormone levels were not available, limiting the interpretation of vitamin D and calcium metabolism. Although imaging protocols were standardized and independently reviewed, measurement errors may still occur.<\/p>\n
Future research should include more patients from multiple centers, with follow-up at several time points. Better tracking of vitamin D supplementation and more detailed metabolic and imaging studies could help clarify the role of vitamin D in body composition changes and long-term outcomes after bariatric surgery.<\/p>\n
Source:<\/p>\n
Journal reference:<\/p>\n","protected":false},"excerpt":{"rendered":"Weight loss tells only part of the story: researchers used CT imaging to examine how vitamin D relates…\n","protected":false},"author":2,"featured_media":659144,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[10],"tags":[11969,118646,6074,11479,6351,5201,5296,6352,4209,3476,296708,296709,16762,163,521,85,5232,46,35064,29962,167,4719,3477,1360,13583,10396,21363,6466,591],"class_list":["post-659143","post","type-post","status-publish","format-standard","has-post-thumbnail","category-health","tag-adipose","tag-bariatric-surgery","tag-bone","tag-calcium","tag-cardiovascular-disease","tag-cholesterol","tag-chronic","tag-chronic-disease","tag-ct","tag-diabetes","tag-gastrectomy","tag-gastric-bypass","tag-hba1c","tag-health","tag-healthcare","tag-il","tag-imaging","tag-israel","tag-lipoprotein","tag-medical-imaging","tag-metabolism","tag-muscle","tag-obesity","tag-research","tag-surgery","tag-type-2-diabetes","tag-vitamin-d","tag-vitamin-d-deficiency","tag-weight-loss"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/posts\/659143","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/comments?post=659143"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/posts\/659143\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/media\/659144"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/media?parent=659143"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/categories?post=659143"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/tags?post=659143"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
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