Walk into any supplement store and you'll see hundreds of products, most implying they're essential for results. In reality, the list of supplements with genuinely strong evidence behind them is short, and it's worth knowing which few actually matter before spending money on the rest.
Worth it: creatine monohydrate
Creatine is one of the most researched supplements in existence, with decades of evidence supporting improved strength, power output, and muscle gain when combined with resistance training, summarized well in the NIH's fact sheet on creatine. It's also inexpensive and has a strong long-term safety record at standard doses (typically 3-5g per day). If you take one supplement beyond a basic protein source, this is the one with the best evidence-to-cost ratio.
Worth it (situationally): protein powder
Protein powder isn't magic, it's just a convenient, concentrated protein source. It's "worth it" specifically if you're struggling to hit your daily protein target through food alone, whether due to appetite, schedule, or cost. If you're already comfortably hitting your protein target through whole foods, powder adds convenience but not additional benefit beyond that.
Worth it: caffeine
Caffeine has strong evidence for improving both endurance and strength performance, along with focus during a session. A standard pre-workout dose is roughly 3-6mg per kilogram of bodyweight, taken 30-60 minutes before training. Coffee works just as well as fancy pre-workout blends for this purpose, you're mostly paying extra for flavoring and marketing in a $30 tub versus a $5 bag of coffee.
Worth it for many people: vitamin D
Vitamin D deficiency is common, particularly for people who spend most of their time indoors or live somewhere with limited sun exposure. Unlike most "performance" supplements, this one is about correcting an actual deficiency rather than enhancing something that's already adequate, worth checking your levels with a basic blood test before assuming you need it, but a common and often genuinely useful supplement.
Weak evidence: BCAAs (branched-chain amino acids)
BCAAs were heavily marketed for years as essential for muscle preservation and recovery. The research since has been fairly clear: if you're already eating adequate total protein (from whole food or a complete protein powder), BCAAs on top of that provide little to no additional benefit. This is one of the more common places people spend money without real return.
Weak evidence: fat burners
Most "fat burner" products rely on small amounts of caffeine and other stimulants, dressed up with a long ingredient list of compounds with minimal independent evidence at the doses used. Fat loss fundamentally comes down to a sustained calorie deficit, no pill meaningfully changes that equation, and some fat burner blends carry real safety concerns from unregulated stimulant combinations.
Mixed evidence: multivitamins
For someone eating a genuinely varied diet, a multivitamin's benefit is minimal, you're likely already covering your micronutrient needs through food. For someone with a restrictive diet or known gaps, a basic multivitamin can be reasonable insurance, but it's not a substitute for eating a varied diet in the first place.
A practical, low-cost starting stack
If you want a simple, evidence-based starting point rather than researching every product individually: a protein source (whole food or powder) to hit your daily target, creatine monohydrate (3-5g daily), caffeine before training if you tolerate it well, and vitamin D if a blood test shows you're low. That combination is backed by real evidence, costs relatively little, and covers the supplements genuinely worth prioritizing.