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Head-to-head evidence comparison — which supplement is right for you?
Orlistat vs Vitamin K2: Vitamin K2 has the stronger overall evidence (5 vs 6/10); they work on different things and are often used together, not either/or. Take the 60-second quiz for a pick tailored to your goals.
Vitamin K2 wins 2 of 3 categories. Both are solid choices — the best pick depends on your specific goals.
Verdict
Mostly mechanism / observational
Top outcomes
Verdict
Probably helps
3 of 5 studies with measurable effects showed benefit.
Top outcomes
Prescription Xenical: 120 mg three times daily (360 mg/day), taken with or up to 1 hour after each main fat-containing meal. Over-the-counter Alli: 60 mg three times daily (180 mg/day). Skip the dose if a meal is missed or contains no fat. Used alongside a reduced-calorie diet in which fat supplies roughly 30% of energy — a higher-fat meal makes the gastrointestinal side effects markedly worse, not the weight loss better.
With meals
Xenical 120 mg capsule three times daily with meals (prescription)
100-200mcg (MK-7)
With a meal containing fat
MK-7 (menaquinone-7)
and 2 more not shown
Reduced vitamin K absorption. In anyone taking warfarin this can destabilise INR — a case report describes orlistat enhancing warfarin effect.
Separate by at least two hours. If you take warfarin, do not start or stop orlistat without INR monitoring.
4–12 weeks to onset; maximal by 6–12 months
Year 2 of continuous use
Years
3–12 months
4-12 weeks
1-3 years
1-3 years
XENical in the prevention of diabetes in obese subjects (XENDOS) study: a randomized study of orlistat as an adjunct to lifestyle changes for the prevention of type 2 diabetes in obese patients.
Diabetes Care (2004) · Rct · n=3305
4-year double-blind trial randomising 3,305 obese patients (BMI ≥30) to lifestyle changes plus orlistat 120 mg or placebo three times daily
Randomised placebo-controlled trial of orlistat for weight loss and prevention of weight regain in obese patients. European Multicentre Orlistat Study Group.
Lancet (1998) · Rct · n=688
743 obese patients (BMI 28–47) entered a 4-week placebo lead-in at 15 European centres; 688 were randomised double-blind to orlistat 120 mg three times a day or placebo for 1 year on a 600 kcal/day-deficit diet, then reassigned for a second 52-week weight-maintenance period
Weight control and risk factor reduction in obese subjects treated for 2 years with orlistat: a randomized controlled trial.
JAMA (1999) · Rct · n=892
2-year randomised, double-blind, placebo-controlled trial at 18 US research centres; 1,187 obese adults (BMI 30–43) entered and 892 were randomised, with 223 placebo- and 657 orlistat-treated subjects in the intent-to-treat analysis
Vitamins K2 and D3 Improve Long COVID, Fungal Translocation, and Inflammation: Randomized Controlled Trial
Nutrients (2025) · Rct · n=151
The median age was 46 years; 71% were female and 29% were non-white.
The effect of vitamin K2 supplementation on bone turnover biochemical markers in postmenopausal osteoporosis patients: a systematic review and meta-analysis
Frontiers in endocrinology (2025) · Meta analysis · n=2570
Vitamin K2 (VK2) increased osteocalcin (OC; MD 1.86, 95% CI 1.17-2.56) and bone-specific alkaline phosphatase (BAP; MD 1.49, 95% CI 0.98-2.00).
Vitamin K2 in Managing Nocturnal Leg Cramps: A Randomized Clinical Trial
JAMA internal medicine (2024) · Rct · n=199
Of the 199 enrolled individuals, 108 (54.3%) were female, and the mean (SD) age was 72.3 (5.5) years.
In a 1-year randomised trial of 311 Chinese men and postmenopausal women, 90 μg of MK-7 a day slowed femoral neck bone loss in the postmenopausal women and 50 μg did not, with no effect in men (PMID 32060566). In a 3-year randomised placebo-controlled trial of 244 healthy postmenopausal women, 180 μg a day reduced the decline in bone density at the lumbar spine and femoral neck but not the total hip (PMID 23525894). In a 3-year randomised placebo-controlled trial of 142 postmenopausal women with osteopenia, 375 μg a day with calcium and vitamin D did not change bone density at any site (PMID 33030563). The curve stays flat above 90 μg because no trial compared 90 μg with a higher dose, and the 375 μg trial found no effect. The cited BMD meta-analyses do not state a dose and mostly pool menaquinone-4 trials, so they are not plotted.
AI-estimated from published studies. Interpret as directional guidance.
Vitamin K2 has a higher evidence score (5/10 vs 6/10) and wins in 2 of 3 categories.
Reduced vitamin K absorption. In anyone taking warfarin this can destabilise INR — a case report describes orlistat enhancing warfarin effect. Separate by at least two hours. If you take warfarin, do not start or stop orlistat without INR monitoring. Consult a healthcare provider for personalized advice.
Which supplements clash with blood thinners, thyroid meds, antibiotics & more — and what to do.
Hot flashes, bone, sleep, muscle — the basics that hold up vs the phytoestrogen hype.
Worth it if you’re deficient (and many are) — dosing, testing, D3 vs D2, and the K2 question.
When to take what, with or without food, and which supplements compete vs pair well.
The right pick depends on your goals. Answer a few quick questions for a personalised recommendation — or dig into the full evidence on each.