Does vitamin B6 help with weight loss?

No. A 2026 network meta-analysis of 68 randomized trials in people with overweight or obesity found that vitamin B supplements did not lower BMI, with a mean difference of -0.20 kg/m2 against placebo and an interval from -1.21 to 0.82 that runs well past zero. That analysis pooled B vitamins together, and we found no review of B6 alone. The one randomized trial of B6 alone, 80 mg a day for 8 weeks in 44 women with overweight or obesity, found no difference in weight or BMI against placebo.

Myth. The idea that vitamin B6 burns fat or boosts metabolism has been tested. Neither the trial of B6 alone nor the trials of B6 with amino acids showed added weight loss over placebo. One multivitamin trial did show lower weight, but B6 was one of many ingredients there. The EU allows a label to say B6 contributes to normal energy-yielding metabolism. That is a claim about a body function working normally, and it does not cover weight loss.

What the trials found

The pooled evidence

The 2026 network meta-analysis compared many supplements with placebo across 68 randomized trials. For the group it labels vitamin B, BMI moved by -0.20 kg/m2, interval -1.21 to 0.82, and waist by -0.68 in (-1.72 cm), interval -3.89 to 0.44. Neither reached significance. Its dose-response analysis found that around 14 mg a day of vitamin B was not enough to change BMI, blood sugar or blood fats. Heterogeneity between trials was moderate to high, from 42.4 to 74.4 percent. The vitamin B group mixed B-complex products with single B vitamins, so it cannot tell you about B6 on its own.

In some of that review's models, vitamin B supplements went with a small rise in fasting insulin, which the authors flagged as a possible unfavorable metabolic effect. That signal comes from few trials and is not a confirmed harm.

The one trial of B6 alone

In Ahvaz, Iran, 44 women aged 18 to 50 with a BMI of 25 or more took 80 mg of pyridoxine hydrochloride a day or a starch placebo for 8 weeks, with no change to their diet. At the end there was no significant difference between groups in weight, BMI, muscle mass, waist or waist-to-hip ratio. The only body measure that differed between groups was the change in fat mass, p = 0.02, measured with a consumer bioimpedance scale and one of many outcomes tested.

Unsettled. The abstract of that trial reports that weight fell in the B6 group, p = 0.03, and BMI fell too, p = 0.023. Those are before-and-after changes within one group. They are not a comparison with placebo, and the comparison with placebo found no difference in weight. Read the headline number with that in mind.

B6 in mixtures

Three more trials gave B6 together with other things, so none can isolate it. In 42 women with overweight or obesity on a 500 calories a day deficit, 6 g of branched-chain amino acids plus 40 mg of B6 for 4 weeks did not add significant weight loss over placebo, 5.4 lb (2.43 kg) against 3.6 lb (1.64 kg). In 20 adults with overweight or obesity, a leucine and B6 blend three times a day for 4 weeks raised fat oxidation by 33.6 g a day, and the abstract reports no weight outcome at all.

Multivitamin trials disagree with each other. In 96 obese Chinese women, a multivitamin and mineral tablet for 26 weeks gave lower body weight, BMI and fat mass than placebo, and the abstract does not give the sizes. In 45 obese adults on a 15-week calorie-cut diet, adding a multivitamin did not increase weight loss over placebo. B6 was one of many ingredients in both.

Low B6 and higher weight

Observational data link the two in the other direction. Among 2,969 US adults aged 60 or older, obese women were more often at risk of too little B6 intake than women of healthy weight. A 2026 review of 16 studies in 20,043 Mexican children found those with overweight or obesity more likely to lack B6, among other nutrients, without a pooled estimate for B6. That is an association. It may reflect diet quality, and it does not show that more B6 lowers weight.

Who should be careful

Not for everyone. The doses tried for weight were 40 to 80 mg a day. In 2023 the EU food safety authority set an upper limit of 12 mg a day for all adults, including women who are pregnant or breastfeeding, based on reviews of B6 and nerve damage. The US limit is 100 mg a day, set at half the dose studied for long-term use because data on harm are limited. The two limits differ about eight-fold.

A 2023 systematic review of 20 articles, mostly case reports, concluded that high B6 levels, usually from supplements, can cause a nerve disorder that affects sensation, and that symptoms improve after stopping. It did not estimate a dose threshold. The 8-week trial at 80 mg a day reported no side effects in 44 women, and it was too short and too small to see nerve damage, which appears with long-term high intake.

The US limit counts B6 from food and supplements together. If you take more than one product that contains B6, the limits above apply to the total.

What expert bodies say

We found no expert body that recommends vitamin B6 for weight loss. The EU register of health claims authorizes a claim that B6 contributes to normal energy-yielding metabolism, which rests on getting enough to avoid deficiency, and it holds no authorized weight claim for B6. The NIH Office of Dietary Supplements fact sheet on B6 carries the EU and US upper limits quoted above. Its separate fact sheet on supplements for weight loss could not be retrieved.

How we searched

What would change this answer

• A meta-analysis of B6 alone on body weight. We found none, and the pooled vitamin B group mixes products.
• A larger trial of B6 alone that runs longer than 8 weeks and reports weight against placebo.
• A trial in people with low B6 status. Obesity goes with lower B6 intake in observational data, and whether correcting a shortfall changes weight has not been tested. ClinicalTrials.gov lists no active trial of B6 for weight.

More on the vitamin itself: vitamin B6 and can you get too much vitamin B6.

Sources

1. ev-b6wl-01 · Meta-analysis or systematic review · systematic review and network meta-analysis of randomized placebo-controlled trials (68 studies, adults and children with overweight or obesity), with dose-response meta-analysis · n = 68 randomized studies
   In comparison, inulin (MD: −0.24 kg/m2; 95% CI: −1.06 to 0.57), butyrate (MD: −0.26 kg/m2; 95% CI: −1.25 to 0.73), vitamin B (MD: −0.20 kg/m2; 95% CI: −1.21 to 0.82), and LC n3-PUFA (MD: −0.18 kg/m2; 95% CI: −1.20 to 0.83) did not result in statistically significant changes when compared to placebo.
   
   Who: children and adults with overweight or obesity in randomized trials of nutraceuticals vs placebo
   Effect: BMI MD -0.20 kg/m2 (95% CI -1.21 to 0.82) vs placebo; L-carnitine MD -1.20 (CI -1.67 to -0.74) for comparison
   Certainty: Pools B-complex and single B vitamins; no B6-only node. Moderate to high heterogeneity (I2 42.4 to 74.4%).
   Front Nutr, 2026 · checked 2026-10-07 · we read the fulltext
2. ev-b6wl-02 · Meta-analysis or systematic review · systematic review and network meta-analysis of randomized placebo-controlled trials (68 studies, adults and children with overweight or obesity), with dose-response meta-analysis · n = 68 randomized studies
   In contrast, vitamin B (MD: −1.72 cm; 95% CI: −3.89 to 0.44), inulin (MD: −1.00 cm; 95% CI: −3.58 to 1.57), and LC n3-PUFA (MD: −0.88 cm; 95% CI: −3.44 to 1.68) did not lead to statistically significant changes.
   
   Who: children and adults with overweight or obesity in randomized trials of nutraceuticals vs placebo
   Effect: waist circumference MD -0.68 in (95% CI -1.5 to 0.17; metric: -1.72 cm, -3.89 to 0.44) vs placebo
   Certainty: Interval includes no effect; vitamin B mixed formulations.
   Front Nutr, 2026 · checked 2026-10-07 · we read the fulltext
3. ev-b6wl-03 · Meta-analysis or systematic review · systematic review and network meta-analysis of randomized placebo-controlled trials (68 studies, adults and children with overweight or obesity), with dose-response meta-analysis · n = 68 randomized studies
   Dose–response analysis indicated that daily intakes of around 14 mg were insufficient to affect BMI, glucose, or lipid outcomes.
   
   Who: children and adults with overweight or obesity in randomized trials of nutraceuticals vs placebo
   Effect: vitamin B at 14 mg/day: no effect on BMI, glucose or lipids at 12 weeks; dose-response not statistically significant
   Certainty: Linear dose-response on few B-vitamin trials; doses above 14 mg/day not modeled.
   Front Nutr, 2026 · checked 2026-10-07 · we read the fulltext
4. ev-b6wl-04 · Meta-analysis or systematic review · systematic review and network meta-analysis of randomized placebo-controlled trials (68 studies, adults and children with overweight or obesity), with dose-response meta-analysis · n = 68 randomized studies
   In some models, vitamin B supplementation was even associated with a small increase in fasting insulin, raising concerns about possible unfavorable metabolic effects.
   
   Who: children and adults with overweight or obesity in randomized trials of nutraceuticals vs placebo
   Effect: small increase in fasting insulin with vitamin B in some models
   Certainty: Model-based signal from few trials; not a confirmed harm.
   Front Nutr, 2026 · checked 2026-10-07 · we read the fulltext
5. ev-b6wl-05 · Randomized controlled trial(s) · randomized double-blind placebo-controlled trial, 80 mg/day pyridoxine hydrochloride (2 x 40 mg) vs starch placebo for 8 weeks, no diet change · n = 44
   There were no significant changes in BMI, weight, muscle mass, WC, WHR, VAI, and physical activity in the subjects after consuming pyridoxine hydrochloride and placebo.
   
   Who: obese and overweight women aged 18-50 years with BMI 25 or higher, Ahvaz, Iran
   Effect: no significant between-group difference in BMI, weight, muscle mass, waist, waist-to-hip ratio or visceral adiposity index after 8 weeks
   Certainty: Small single-center trial; 44 enrolled; analyzed by t-tests and ANCOVA.
   Clinical Nutrition Research, 2021 (pyridoxine hydrochloride supplementation in obese and overweight women: randomised double-blind placebo-controlled trial) · checked 2026-10-07 · we read the fulltext
6. ev-b6wl-06 · Randomized controlled trial(s) · randomized double-blind placebo-controlled trial, 80 mg/day pyridoxine hydrochloride (2 x 40 mg) vs starch placebo for 8 weeks, no diet change · n = 44
   At the end of the study, we just observed a significant difference in fat mass changes (p = 0.02).
   
   Who: obese and overweight women aged 18-50 years with BMI 25 or higher, Ahvaz, Iran
   Effect: fat mass change differed between groups, p = 0.02; weight and BMI did not
   Certainty: Fat mass by consumer bioimpedance scale (Omron BF511); one of many outcomes tested.
   Clinical Nutrition Research, 2021 (pyridoxine hydrochloride supplementation in obese and overweight women: randomised double-blind placebo-controlled trial) · checked 2026-10-07 · we read the fulltext
7. ev-b6wl-07 · Randomized controlled trial(s) · randomized double-blind placebo-controlled trial, 80 mg/day pyridoxine hydrochloride (2 x 40 mg) vs starch placebo for 8 weeks, no diet change · n = 44
   In the intervention group, weight (p = 0.03), BMI (p = 0.023), fat mass (p = 0.003), WC (p = 0.005) and VAI (p = 0.001) decreased significantly after 8 weeks.
   
   Who: obese and overweight women aged 18-50 years with BMI 25 or higher, Ahvaz, Iran
   Effect: within-group: weight p = 0.03, BMI p = 0.023, fat mass p = 0.003, waist p = 0.005 after 8 weeks; placebo no change
   Certainty: Within-group P values are not a test against placebo; the between-group test for weight was null (ev-b6wl-05).
   Clinical Nutrition Research, 2021 (pyridoxine hydrochloride supplementation in obese and overweight women: randomised double-blind placebo-controlled trial) · checked 2026-10-07 · we read the fulltext
8. ev-b6wl-08 · Randomized controlled trial(s) · randomized double-blind placebo-controlled trial, 80 mg/day pyridoxine hydrochloride (2 x 40 mg) vs starch placebo for 8 weeks, no diet change · n = 44
   There was not any report of complication or side effect due to intake of pyridoxine hydrochloride supplement by the participants during the study.
   
   Who: obese and overweight women aged 18-50 years with BMI 25 or higher, Ahvaz, Iran
   Effect: no complications or side effects reported, 80 mg/day for 8 weeks
   Certainty: Short trial, 44 women; not powered for neuropathy, which appears with long-term high intake.
   Clinical Nutrition Research, 2021 (pyridoxine hydrochloride supplementation in obese and overweight women: randomised double-blind placebo-controlled trial) · checked 2026-10-07 · we read the fulltext
9. ev-b6wl-09 · Randomized controlled trial(s) · randomized placebo-controlled trial, BCAA 6 g/day + vitamin B6 40 mg/day, 4 weeks · n = 42
   The result indicated that, weight loss was not significantly affected by BCAA and vitamin B6 supplementation (-2.43 ± 1.02 kg) or placebo (-1.64 ± 1.48 kg).
   
   Who: overweight and obese women (BMI 25 to 34.9) on a -500 calories/day diet
   Effect: weight change -2.43 +/- 1.02 kg with BCAA + B6 vs -1.64 +/- 1.48 kg with placebo, not significant; leg lean mass preserved
   Certainty: B6 effect cannot be separated from BCAA; 4 weeks; bioimpedance.
   Int J Vitam Nutr Res, 2018 · checked 2026-10-07 · we read the abstract
10. ev-b6wl-10 · Randomized controlled trial(s) · randomized placebo-controlled trial, NuFit active blend (2.25 g leucine + 30 mg pyridoxine) three times daily, 4 weeks · n = 20
    Administration of NuFit active blend in the clinical trial increased fat oxidation by 33.6 g/day (p < 0.04), decreased respiratory quotient, improved HOMA(IR), reduced oxidative and inflammatory biomarkers (plasma MDA, 8-isoprostane-F(2α), TNF-α, C-reactive protein), and increased the anti-inflammatory marker adiponectin.
    
    Who: overweight or obese subjects without energy restriction
    Effect: fat oxidation +33.6 g/day (p < 0.04); lower respiratory quotient; HOMA-IR improved; no body weight outcome reported in abstract
    Certainty: Very small; combination product; surrogate outcome; abstract also reports cell work (not counted here).
    Nutrients, 2012 · checked 2026-10-07 · we read the abstract
11. ev-b6wl-11 · Randomized controlled trial(s) · randomized double-blind placebo-controlled trial, three arms (multivitamin-mineral, calcium 162 mg, placebo), 26 weeks · n = 96 (87 completed)
    After 26 weeks, compared with the placebo group, the MMS group had significantly lower BW, BMI, FM, TC and LDL-C, significantly higher REE and HDL-C, as well as a borderline significant trend of lower RQ (P=0.053) and WC (P=0.071).
    
    Who: obese Chinese women aged 18-55 years (BMI about 28)
    Effect: lower body weight, BMI and fat mass vs placebo, higher resting energy expenditure; sizes not given in abstract
    Certainty: Multinutrient tablet; cannot attribute any effect to vitamin B6; single trial, not replicated in 17977472.
    Int J Obes (Lond), 2010 · checked 2026-10-07 · we read the abstract
12. ev-b6wl-12 · Randomized controlled trial(s) · randomized double-blind placebo-controlled trial, 15 weeks · n = 45
    In study 2, body weight was significantly decreased after the weight-loss intervention (P < 0.001) with no difference between treatment groups.
    
    Who: obese non-consumers of supplements on a 15-week energy restriction (-2930 kJ/d)
    Effect: weight fell in both groups (P < 0.001) with no difference between multivitamin and placebo
    Certainty: Multinutrient product; small.
    Br J Nutr, 2008 · checked 2026-10-07 · we read the abstract
13. ev-b6wl-13 · Observational data · cross-sectional analysis of national survey data · n = 2969
    A greater percentage of obese older adults compared with their healthy-weight counterparts was at risk of inadequate Mg (both sexes), Ca, vitamin B6 and vitamin D (women only) intakes.
    
    Who: US adults aged 60 years or older (NHANES), by sex and BMI category
    Effect: higher share at risk of inadequate vitamin B6 intake in obese vs healthy-weight older women; percentages not given in abstract
    Certainty: Association; says nothing about whether B6 changes weight.
    Public Health Nutr, 2020 · checked 2026-10-07 · we read the abstract
14. ev-b6wl-14 · Observational data · systematic review of observational studies with meta-analysis of 4 studies (vitamin D only) · n = 20043
    Current evidence suggests that Mexican children who have overweight or obesity are more likely to have zinc, iron, and vitamins D and B6 deficiency.
    
    Who: Mexican children and adolescents
    Effect: more likely to have zinc, iron, vitamin D and vitamin B6 deficiency with overweight or obesity; pooled OR only for vitamin D (1.84)
    Certainty: Observational; no pooled estimate for B6; deficiency may follow diet quality rather than cause weight gain.
    Nutr Rev, 2026 · checked 2026-10-07 · we read the abstract
15. ev-b6wl-15 · Position of an expert body · agency fact sheet · n = —
    Based on systematic reviews that examined associations between vitamin B6 and peripheral neuropathy, the panel set an upper limit for vitamin B6 of 12 mg/day for all adults, including women who are pregnant or lactating, with lower amounts ranging from 2.2 to 10.7 mg/day for infants and children, depending on age.
    
    Who: adults including pregnant and lactating women (EU)
    Effect: EU UL 12 mg/day; children 2.2 to 10.7 mg/day; critical effect peripheral neuropathy
    Certainty: EU and US limits differ about eight-fold (12 vs 100 mg/day).
    NIH Office of Dietary Supplements, Vitamin B6 Fact Sheet for Health Professionals · checked 2026-10-07 · we read the section
16. ev-b6wl-16 · Position of an expert body · agency fact sheet · n = —
    Based on limitations in the data on potential harms from long-term use, the FNB halved the dose used in these studies to establish a UL of 100 mg/day for adults.
    
    Who: US adults
    Effect: US UL 100 mg/day from food and supplements combined; lower for children by body size
    Certainty: US limit does not apply to medical treatment under a physician.
    NIH Office of Dietary Supplements, Vitamin B6 Fact Sheet for Health Professionals · checked 2026-10-07 · we read the section
17. ev-b6wl-17 · Observational data · systematic review of case reports and observational studies (PubMed only) · n = 20 articles
    Higher vitamin B6 levels, which usually occur following the taking of nutritional supplements, may lead to the development of a predominantly, if not exclusively, sensory neuropathy of the axonal type.
    
    Who: people with peripheral neuropathy related to low or high vitamin B6
    Effect: predominantly sensory axonal neuropathy with high B6 levels; symptoms improve after stopping pyridoxine
    Certainty: Mostly case reports; no dose threshold estimated.
    Nutrients, 2023 · checked 2026-10-07 · we read the abstract
18. ev-b6wl-18 · Position of an expert body · regulatory register entry · n = —
    POL-HC-6491 Vitamin B6 Vitamin B6 contributes to normal energy-yielding metabolism Authorised
    
    Who: EU food and supplement labeling
    Effect: authorized claim on normal energy-yielding metabolism; no authorized weight claim for vitamin B6
    Certainty: The claim rests on adequate intake preventing deficiency, not on extra B6 burning fat.
    EU Register on nutrition and health claims, claim POL-HC-6491, snapshot 2026-09-21 · checked 2026-10-07 · we read the section