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Supplements for weight loss

Evidence-based adjuncts to the things that actually drive weight loss — caloric deficit, training, sleep, and (where indicated) prescription GLP-1 therapy.

The weight-loss aisle is the worst-evidence corner of the supplement market. The vast majority of "fat burners," "metabolism boosters," and "carb blockers" deliver small placebo-comparable effects or no effects at all, and the most aggressive thermogenic stimulants have documented cardiovascular and liver injury signals. The supplements that have a genuine role in evidence-based weight loss are unglamorous: adequate protein to preserve lean mass during a caloric deficit, soluble fibre to support satiety and glycaemic stability, modest caffeine for training-day energy, and selected micronutrient gap-filling. Note that prescription anti-obesity medications (GLP-1 receptor agonists, GLP-1/GIP dual agonists) now produce weight-loss outcomes (15–25% body weight) that no supplement comes close to matching. The framing here is "adjuncts" — not alternatives.

Whey protein

Preserves lean mass · Satiety · Anabolic during deficit

Tier 1

Psyllium husk (soluble fibre)

Satiety · Glycaemic stability · Lipid improvement

Tier 1

Caffeine (standardised)

Training-day energy · Modest metabolic effect

Tier 1

Creatine monohydrate

Preserves strength during deficit · Resistance training

Tier 1

Vitamin D3

Common deficiency · Immune · Bone protection during weight loss

Tier 1

Magnesium glycinate

Sleep · Stress · Glucose handling adjunct

Tier 1

Berberine

Glucose & lipid handling · Metabolic substrate

Tier 2

Glucomannan (konjac root)

Pre-meal satiety · Fibre supplementation

Tier 2

The weight-loss stack — rationale by ingredient

Whey protein 25–40 g per serving, 2× per day

The single most important supplement during a caloric deficit. Adequate protein (1.6–2.2 g/kg/day total) preserves lean mass when calories are restricted; without it, a significant fraction of weight loss is muscle, which compromises long-term metabolic rate and physical function. Whey provides a clean leucine pulse to support muscle-protein synthesis; plant-blend protein works too at slightly higher doses.

Psyllium husk 5–10 g/day, divided

The most-evidenced fibre supplement for satiety, glycaemic stability, and modest lipid improvements. Pre-meal dosing modestly reduces meal intake. Tolerable across most users; titrate up to manage initial bloating.

Caffeine 100–200 mg pre-training

The most-evidenced ergogenic for training performance. Modest acute thermogenic effect; the dominant value is supporting training adherence during a caloric deficit when energy is lower.

Creatine monohydrate 5 g/day continuous

Preserves strength and lean mass during caloric restriction better than placebo. Some short-term water retention initially; the lean-mass and strength preservation is what matters for long-term outcomes.

Vitamin D3 to a 25-OH-D target of 30–50 ng/mL

Deficiency is common; correction supports immune, bone, and muscle function. Bone density should be supported during weight loss (particularly in older adults and after bariatric surgery).

Magnesium glycinate 300 mg/day in the evening

Sleep quality is one of the strongest non-dietary predictors of weight-loss adherence. Magnesium supports sleep maintenance and provides modest glycaemic stability benefit.

Berberine 500 mg × 2–3/day with meals (selected users)

For users with insulin resistance, prediabetes, T2D, or PCOS who are also targeting weight loss, berberine improves insulin sensitivity and modestly supports the metabolic substrate. Coordinate with prescriber if on metformin or GLP-1 therapy.

Glucomannan 1–2 g 30 minutes before meals (optional)

Soluble fibre with stronger pre-meal satiety effects than psyllium in some trials. Take with adequate water to avoid esophageal obstruction risk.

What to skip — most of the weight-loss aisle

Garcinia cambogia / HCA — null trials at scale; hepatotoxic case reports.
Raspberry ketones — no human weight-loss evidence.
CLA (conjugated linoleic acid) — small effect sizes that don't translate to meaningful body-composition change.
Bitter orange (synephrine) — cardiovascular safety signals (hypertension, arrhythmia, MI case reports). Avoid.
Yohimbine — adrenergic, anxiogenic, cardiovascular risk; weak fat-loss signal in localized adipose.
DMAA / DMHA — banned/regulated stimulants with serious cardiovascular safety concerns. Avoid.
Green tea extract (high-dose) — hepatotoxic case reports at high doses; modest weight-loss effect at best.
Apple cider vinegar (high-dose) — minimal weight effect; esophageal and dental damage at high doses.
"Carb blocker" white kidney bean extract — small effect, mostly inflated by manufacturer trials.
Detox / cleanse "kits" — typically laxatives and diuretics; produce water loss, not fat loss; risk electrolyte disturbance.
"Thermogenic" fat-burner blends — typically stimulant cocktails with proprietary blends, variable dosing, and the cardiovascular risk profile of high-dose caffeine plus other stimulants.
Forskolin (Coleus forskohlii) — limited human evidence for weight loss.
2,4-DNP (dinitrophenol) — illegal, lethal. Do not use under any circumstance.
Clenbuterol — illegal for human use as a weight-loss agent; cardiovascular risk.

Educational reference, not medical advice. For substantial weight loss (BMI ≥27 with comorbidities, BMI ≥30 generally), GLP-1 receptor agonists and other prescription anti-obesity medications now produce outcomes no supplement can match. Discuss with a clinician if appropriate. Pre-surgical and post-bariatric supplement strategy is specific and should be coordinated with your bariatric team.

Sources

Pasiakos SM, et al. The effects of protein supplements on muscle mass, strength, and aerobic and anaerobic power in healthy adults. Sports Med. 2015;45(1):111–131. PMID: 25169440
Wadden TA, et al. Behavioral treatment of obesity: Achievements and challenges. Med Clin North Am. 2018;102(1):149–165. PMID: 29156184
Brum J, et al. Meta-analysis of usefulness of psyllium fiber as adjuvant antilipid therapy. Am J Cardiol. 2018;121(11):1303–1308. PMID: 29680303
Onakpoya I, et al. The efficacy of glucomannan supplementation in overweight and obesity: a systematic review and meta-analysis of randomized clinical trials. J Am Coll Nutr. 2014;33(1):70–78. PMID: 24533610
Wilding JPH, et al. Once-weekly semaglutide in adults with overweight or obesity. N Engl J Med. 2021;384(11):989–1002. PMID: 33567185
Lan J, et al. Meta-analysis of the effect and safety of berberine in the treatment of type 2 diabetes mellitus. J Ethnopharmacol. 2015;161:69–81. PMID: 25498346