Walk into any supplement store, fitness expo, or online fitness marketplace and you will quickly notice one thing: there is no shortage of products claiming to accelerate muscle growth, improve recovery, increase performance, and optimize health.
The supplement industry is enormous, and for good reason. Supplements are appealing. They provide the feeling that we are adding another layer of optimization to our fitness goals. They are easy to purchase, easy to consume, and often marketed with bold promises that suggest meaningful improvements in physique and performance.
The problem is that supplement effectiveness is frequently exaggerated.
Many companies market products based on theoretical mechanisms rather than meaningful real-world outcomes. In some cases, individuals promoting supplements have little understanding of the underlying research. The reality is that supplements are profitable, and profitability often drives marketing far more than scientific evidence.
This creates a situation where consumers spend hundreds or even thousands of dollars per year on products that provide little to no measurable benefit.
Before discussing specific supplements, it is important to establish the scope of this article. This review is focused specifically on supplements related to fitness, resistance training performance, muscle growth, and recovery. It is not intended to cover clinical supplementation for medical conditions or general health interventions prescribed by healthcare professionals.
To simplify things, we will divide supplements into three categories:
Category C: Supplements you should probably never purchase.
Category B: Supplements that may be useful depending on context, but are probably not worth buying.
Category A: Supplements that consistently demonstrate meaningful benefits and are generally worth considering.
Category C: Supplements You Should Probably Never Purchase
Branched-Chain Amino Acids (BCAAs) and Essential Amino Acids (EAAs)
I am intentionally spending more time on this category because BCAAs and EAAs continue to be among the most heavily marketed supplements despite some of the strongest evidence suggesting they provide little additional benefit for most resistance-trained individuals.
Amino acids are the building blocks of protein. Essential amino acids are amino acids that must be consumed through the diet because the body cannot synthesize them independently. Branched-chain amino acids are a subset of essential amino acids consisting of leucine, isoleucine, and valine.
Of these three, leucine receives the most attention because it plays a major role in activating the mechanistic Target of Rapamycin Complex 1 (mTORC1), which is the primary molecular regulator of muscle protein synthesis. Muscle protein synthesis refers to the process through which the body builds new muscle proteins, including myofibrillar proteins that ultimately contribute to muscle growth and repair.
While leucine serves as an important trigger, it is not the primary determinant of long-term muscle growth.
The two major regulators of muscle protein synthesis are:
- Total energy intake.
- Total protein intake.
Simply triggering mTORC1 is not enough. The body still requires sufficient energy and sufficient amino acid availability to actually construct new muscle tissue.
This distinction becomes important when evaluating supplementation research.
Plotkin et al. pooled the results of seven randomized controlled trials examining BCAA and EAA supplementation. Their meta-analysis concluded that when individuals consume adequate calories and adequate daily protein, additional BCAA or EAA supplementation provides no meaningful benefit for muscle hypertrophy or strength development compared to controls.
In practical terms, if your protein intake is already sufficient, adding BCAAs on top of that is unlikely to improve your results.
There may be limited situations where supplementation could provide some value. Dieter et al. reported greater muscle retention during a hypocaloric dieting phase among college-aged males supplementing with BCAAs. However, the authors acknowledged multiple statistical and methodological limitations that make strong conclusions difficult.
Furthermore, energy availability itself is a major regulator of mTORC1 activity and subsequent protein translation. If preserving muscle mass during a diet is the goal, it is reasonable to ask why someone would spend money on a low-calorie amino acid supplement rather than simply consuming sufficient energy and increasing the proportion of calories coming from high-quality protein sources.
The overwhelming majority of lifters would likely achieve superior outcomes by focusing on total protein intake rather than purchasing BCAA or EAA products.
Beta-Alanine
Beta-alanine is a non-essential amino acid commonly included in pre-workout supplements.
Its primary purpose is to increase intramuscular carnosine concentrations. Carnosine acts as a buffer against hydrogen ion accumulation during exercise. As hydrogen ions accumulate, muscle acidity increases, contributing to fatigue. In theory, increasing carnosine concentrations could delay fatigue and improve performance.
The problem is that the practical benefits for resistance training are relatively small, highly context dependent, and often overstated.
Additionally, beta-alanine frequently produces paresthesia, the tingling sensation many people experience after consuming pre-workout supplements. While harmless, many individuals find it uncomfortable.
When considering the modest potential benefits relative to cost, beta-alanine is difficult to justify for most recreational lifters.
Other Examples
Other supplements that generally fall into this category include:
- Glutamine
- Sodium bicarbonate
- Beetroot powder
This does not necessarily mean these supplements are completely ineffective under every circumstance. Rather, they either lack convincing evidence demonstrating meaningful improvements in long-term adaptations such as hypertrophy and strength, or the available evidence is not strong enough to justify routine purchasing for most individuals.
Category B: Supplements That May Be Useful Depending on Context, But Are Probably Not Worth Buying
Magnesium
Magnesium supplementation has become increasingly popular, particularly among individuals seeking improvements in sleep quality, recovery, relaxation, and anxiety-related symptoms.
The appeal is understandable. Sleep is one of the most important factors influencing recovery, performance, and overall health. If a relatively inexpensive supplement could reliably improve sleep quality, it would likely be worth considering.
Unfortunately, the evidence is not currently convincing enough to support strong recommendations.
Arab et al. performed a comprehensive meta-analysis examining magnesium supplementation and sleep-related outcomes. Their review concluded that magnesium supplementation may improve certain aspects of sleep quality, but the available evidence remains inconsistent and insufficient to make firm conclusions.
A common theme emerges throughout this article.
Many supplements have theoretical mechanisms that appear promising. However, when researchers aggregate the highest-quality evidence, the results are often mixed, inconsistent, or inconclusive.
At present, it is difficult to confidently state that magnesium supplementation meaningfully improves sleep quality in most healthy individuals.
In my opinion, the money is better invested in strategies that we know consistently influence sleep:
- Maintaining regular bedtimes and wake times.
- Creating a consistent nighttime routine.
- Limiting caffeine intake later in the day.
- Reducing environmental disruptions before sleep.
Arab et al. specifically noted that additional high-quality randomized controlled trials are needed before stronger recommendations can be made.
Nitric Oxide Boosters (L-Citrulline and Arginine)
Nitric oxide (NO) boosters are among the most common ingredients found in modern pre-workout supplements.
Nitric oxide is a signaling molecule that promotes vasodilation, the widening of blood vessels. Increased vasodilation can improve blood flow to working muscles, contributing to the "pump" sensation many lifters experience during training.
The theory is straightforward:
Greater blood flow may improve nutrient delivery, enhance training performance, and potentially support greater training volumes.
The two most common nitric oxide supplements are arginine and L-citrulline.
Interestingly, much of the supplement industry has shifted away from arginine and toward L-citrulline because L-citrulline serves as a precursor to arginine and appears more effective at elevating circulating arginine levels.
The primary issue is dosage.
Research suggests that relatively large doses are required to maximize nitric oxide production and vasodilation. Doses approaching 8–10 grams of L-citrulline appear substantially more effective than lower doses.
However, most commercial pre-workout products contain considerably less. Many products include only one-third to one-half of the amount likely needed to maximize physiological effects.
The reason is simple: high-quality citrulline is expensive.
As a result, many consumers purchase products specifically for nitric oxide enhancement without realizing they are receiving suboptimal doses.
This does not mean citrulline is ineffective. Rather, it means many products containing citrulline are unlikely to provide the full effects advertised on the label.
Other Examples
Other supplements that may have downstream effects on performance but require substantially more research include:
- Ashwagandha
While some studies report promising findings, the overall body of evidence remains insufficient to justify routine supplementation for most individuals.
Category A: Supplements That Actually Work
Whey Protein
Unlike BCAA supplements, whey protein provides a complete protein source containing all essential amino acids.
Importantly, whey protein contains substantial amounts of leucine, the amino acid responsible for activating mTORC1 signaling and initiating muscle protein synthesis.
However, unlike isolated BCAA products, whey also provides the remaining amino acids necessary to actually construct new muscle tissue.
This makes whey protein a practical and effective tool for increasing daily protein intake.
For individuals attempting to lose body fat, whey protein can be particularly useful because it provides a large amount of protein with relatively few calories compared to many whole-food alternatives.
The value of whey protein is not that it possesses magical muscle-building properties. Its value lies in helping individuals consistently achieve adequate daily protein intake.
Creatine Monohydrate
If there were a single supplement that consistently deserves its reputation, creatine would likely be the strongest candidate.
Creatine functions as part of the phosphagen energy system.
During high-intensity activities such as resistance training, ATP (adenosine triphosphate) serves as the immediate source of energy for muscular contraction. ATP stores are extremely limited and become depleted rapidly.
Creatine phosphate helps regenerate ATP at very high rates, allowing muscles to sustain force production during repeated bouts of intense exercise.
Over time, this translates into improved training quality and greater adaptations.
Numerous studies have demonstrated that creatine supplementation increases lean body mass and improves strength-related outcomes.
There is also growing interest in potential cognitive benefits, although this area remains less established than the performance literature.
A daily dose of approximately 5–10 grams is sufficient for most individuals.
One common concern is water retention. This concern is often overstated.
Creatine does increase intracellular water content, meaning water is drawn into muscle tissue. However, this is fundamentally different from the bloated appearance many people fear. While some increase in body mass may occur, concerns regarding "water weight" are often exaggerated relative to the actual physiological effect.
Burke et al. conducted a meta-analysis demonstrating that creatine supplementation improves lean body mass while also helping address many misconceptions surrounding fluid retention and body composition changes.
Caffeine
Caffeine is one of the most extensively studied ergogenic aids in existence.
An ergogenic aid is anything that improves exercise performance.
One of caffeine's primary mechanisms is reducing perceived exertion, meaning exercise feels easier despite performing the same amount of work. This allows individuals to sustain higher training outputs and often improves performance across a variety of exercise modalities.
There are also several additional proposed mechanisms involving the central nervous system, neurotransmitter activity, excitation-contraction coupling, and neuromuscular function.
The practical outcome is clear:
Caffeine consistently improves performance.
Guest et al. summarized a substantial body of literature supporting caffeine as an effective ergogenic aid for exercise performance.
Unlike many supplements discussed earlier, caffeine's effects are reproducible, measurable, and consistently demonstrated across numerous studies.
Final Thoughts
The supplement industry thrives on the promise of optimization.
Unfortunately, most supplements fail to deliver meaningful improvements in muscle growth, strength development, recovery, or performance once adequate nutrition and training are already in place.
This does not mean every supplement is useless. It simply means that the hierarchy matters.
Before spending money on supplements, focus on the variables that consistently produce results:
- Adequate calorie intake.
- Adequate protein intake.
- Progressive resistance training.
- High-quality sleep.
- Long-term consistency.
Once those factors are established, a small number of supplements may provide meaningful benefits.
For most individuals, that list is surprisingly short.
Whey protein. Creatine. Caffeine.
Everything else should be viewed with a much greater degree of skepticism.
References:
1. Arab, A., Rafie, N., Amani, R., & Shirani, F. (2023). The role of magnesium in sleep health: a systematic review of available literature. Biological Trace Element Research, 201(1), 121–128. https://doi.org/10.1007/s12011-022-03162-1
2. Burke, D. G., et al. (2023). https://doi.org/10.3390/nu15092116 Nutrients. https://doi.org/10.3390/nu15092116
3. Dieter, B. P., Schoenfeld, B. J., & Aragon, A. A. (2016). The data do not seem to support a benefit to BCAA supplementation during periods of caloric restriction. Journal of the International Society of Sports Nutrition, 13(1), 21. https://doi.org/10.1186/s12970-016-0128-9
4. Guest, N. S., VanDusseldorp, T. A., Nelson, M. T., et al. (2021). International society of sports nutrition position stand: caffeine and exercise performance. Journal of the International Society of Sports Nutrition, 18(1), 1. https://pubmed.ncbi.nlm.nih.gov/33388079/
5. Plotkin, D. L., Delcastillo, K., Van Every, D. W., Tipton, K. D., Aragon, A. A., & Schoenfeld, B. J. (2021). Isolated leucine and branched-chain amino acid supplementation for enhancing muscular strength and hypertrophy: a narrative review. International Journal of Sport Nutrition and Exercise Metabolism, 31(3), 292–301. https://doi.org/10.1123/ijsnem.2020-0356