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Vitamin D for Obesity

B

Meta-analysis of 11 RCTs (n=947) found significant BMI reduction in deficient overweight/obese individuals. Mendelian randomization study (n=42,024) confirms causal association between low vitamin D and higher BMI. Correction of deficiency appears critical for benefits.

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            B

        

        

            
The Bottom Line

            
            
Meta-analysis of 11 RCTs (n=947) found significant BMI reduction in deficient overweight/obese individuals. Mendelian randomization study (n=42,024) confirms causal association between low vitamin D and higher BMI. Correction of deficiency appears critical for benefits.

            
            
        

    











    
    

        
        

            

  
Key Statistics





            


    

        
11

        
Studies

    

    

        
947

        
Participants

    

    

        
            
            ↑
            
        
        
Positive

    

    

        B

        
Grade

    




        


        
        

        
        
        

            

  
Dosage & Usage





            
mg = milligrams · mcg = micrograms (1,000× smaller) · IU = International Units


            
            

                
Commonly Used Dosages

                

                    
                    

                        
general:

                        
600-800 IU/day

                    

                    
                    

                        
weightmanagement:

                        
2,000-4,000 IU/day (targeting 25(OH)D >30 ng/mL)

                    

                    
                    

                        
deficiencycorrection:

                        
5,000-10,000 IU/day for 8-12 weeks under medical supervision

                    

                    
                

                
                

                    Upper limit: 4,000 IU/day (100 mcg); higher doses under medical supervision
                

                
            

            

            

            
            

                Best taken: With a meal containing fat for absorption; morning preferred
            

            
        

        

        
        
        

            

  
Safety & Side Effects





            

                
                

                    
Reported Side Effects

                    
    
                        
                        
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                            ⚠
                            Hypercalcemia (at very high doses)
                        
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                            ⚠
                            Nausea
                        
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                            ⚠
                            Kidney stones (at excessive doses)
                        
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Known Interactions

                    
    
                        
                        
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                            ●
                            Statins (may increase statin levels)
                        
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                            ●
                            Thiazide diuretics (increased calcium risk)
                        
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                            Corticosteroids (impair vitamin D metabolism)
                        
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                            ●
                            Orlistat (reduced absorption)
                        
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                        Tolerable upper intake: 4,000 IU/day (100 mcg); higher doses under medical supervision
                    

                

                
            

            

                Always consult your healthcare provider before starting any supplement.
            

        

        

        
        
        

            

  
Frequently Asked Questions





            




    
    

        
            Does Vitamin D help with Obesity?
            
        
        

            Based on 11 studies with 947 participants, there is moderate evidence from clinical studies that Vitamin D may support Obesity management. Our evidence grade is B (Good Evidence).
        

    

    
    

        
            How much Vitamin D should I take for Obesity?
            
        
        

            Studies have used various dosages. A commonly studied range is 600-800 IU/day. Always consult your healthcare provider before starting any supplement regimen.
        

    

    
    

        
            Are there side effects of Vitamin D?
            
        
        

            Reported side effects may include Hypercalcemia (at very high doses), Nausea, Kidney stones (at excessive doses). Most side effects are mild and dose-dependent. Consult your doctor if you experience any adverse reactions.
        

    

    
    

        
            How strong is the evidence for Vitamin D and Obesity?
            
        
        

            We rate the evidence as Grade B (Good Evidence). This rating is based on 11 peer-reviewed studies with 947 total participants. The overall direction of effect is positive.
        

    

    




        

        

        
        
        

            

  
Related Evidence





            

                
                
                

                
                
                
            

        

        

    


    
    












    

        FDA Disclaimer:
        These statements have not been evaluated by the Food and Drug Administration. The products and information on this website are not intended to diagnose, treat, cure, or prevent any disease. The evidence grades presented are based on our analysis of published peer-reviewed research and do not constitute medical advice. Always consult your healthcare provider before starting any supplement regimen.