Paid partnership disclosure. This article names Prozis, a brand I have a commercial partnership with, and includes a discount code I earn from. I only name products I use myself, and the evidence summarised below comes from the sources listed at the end, not from the brand.
For most women training seriously, only a short list has real evidence behind it. Creatine monohydrate has the strongest support for strength and lean mass, protein powder is a convenient way to reach a daily protein target of roughly 1.6 g per kilogram, and caffeine reliably improves performance at 3 to 6 mg per kilogram. Everything else is situational.
- Creatine monohydrate is the most evidence-backed supplement for strength and lean mass, at 3 to 5 g a day.
- Protein powder is convenience, not a special ingredient — the target is total daily protein, around 1.6 g per kilogram.
- Caffeine works at 3 to 6 mg per kilogram, roughly an hour before training; higher doses add side effects, not performance.
- None of these replaces food, sleep, or a training plan you can actually keep to.
Which supplements actually have evidence behind them?
Fewer than the shelf suggests. A good result in the gym starts with enough food, a plan that matches your goal, enough sleep, and consistency. Nothing below changes that order.
What the products below have in common is that they are boring and well studied. That is the whole reason I use them. The interesting-sounding supplement is almost always the one with the thinnest evidence.
Do you actually need protein powder?
No, and that is the honest answer. You need protein. Powder is one convenient way to get it.
A meta-analysis of 49 studies found that protein supplementation significantly increases gains in muscle mass and strength from resistance training, with the benefit levelling off around 1.6 g per kilogram of body weight per day. The important word is total: what matters is your intake across the day, not whether part of it arrived as a shake.
Where a shake earns its place is on the days when cooking a full protein-rich meal is not realistic. You can take it to work or the gym and close the gap. That is a logistics problem solved, not a physiological advantage bought.
Is creatine worth taking as a woman?
Of everything in this article, creatine monohydrate has the strongest evidence behind it. The International Society of Sports Nutrition calls it “the most effective ergogenic nutritional supplement currently available to athletes with the intent of increasing high-intensity exercise capacity and lean body mass during training.”
On dosing, their position stand describes a loading protocol of roughly 0.3 g per kilogram of body weight daily for five to seven days, followed by 3 to 5 g a day to maintain elevated muscle stores. Loading is optional; taking 3 to 5 g a day from the start reaches the same place more slowly.
On safety, the same position stand reports no compelling scientific evidence that short- or long-term use has detrimental effects in otherwise healthy people, and notes that the only consistently reported side effect in the literature is weight gain — largely water held inside the muscle, not fat. If you take medication or have a diagnosed condition, discuss it with your GP first; that is a conversation for a doctor, not for a coach or a blog.
What creatine will not do is produce a visible difference from one day to the next. It is a long-term, consistent-use product, and it does not substitute for the training that makes it useful.
What does a pre-workout actually do?
The part of a pre-workout with solid evidence behind it is almost always the caffeine. The ISSN position stand on caffeine puts the effective range at 3 to 6 mg per kilogram of body weight, most commonly taken about 60 minutes before exercise, with small to moderate benefits across muscular endurance, strength, movement velocity, sprinting and jumping.
Two things in that stand are worth holding onto. Very high doses, around 9 mg per kilogram, bring a high rate of side effects without being needed for the effect. And the benefits show up in both trained and untrained people, so this is not an advanced-lifter tool.
My own rule has not changed: it is useful on the days your energy is genuinely low. Needing a large dose to get through every single session is information about your sleep and recovery, not a reason to increase the dose.
Where do snacks and convenience products fit?
A fitness routine does not mean eating only rice, chicken and broccoli. If a way of eating is going to last, it has to have room for food you enjoy.
A protein-rich snack or a bar you actually like is genuinely useful when you are out and need something between meals. The goal is not to make your nutrition as clean as possible. The goal is a way of eating that fits your calories, your protein target, and your week.
How do these compare side by side?
| Product | What the evidence supports | Typical amount | When it helps |
|---|---|---|---|
| Creatine monohydrate | High-intensity exercise capacity and lean body mass | 3–5 g daily, long term | Strength and muscle goals, used consistently |
| Protein powder | Gains in muscle mass and strength via total daily protein | Enough to reach ~1.6 g/kg/day in total | Days when a full meal is not realistic |
| Caffeine / pre-workout | Small to moderate gains in endurance, strength, speed | 3–6 mg/kg, ~60 min before training | Genuinely low-energy training days |
| Protein snacks | No direct performance claim — adherence only | As fits your daily intake | Making a plan sustainable |
Amounts are from the position stands and review listed under Sources. General information, not medical or individual dietary advice.
What should you not expect from any of this?
Supplements are an addition to your basics, not a replacement for good food, training, sleep and recovery. That sounds obvious written down, and it is still the thing most often ignored in practice.
You do not build a strong physique with one product. You build it with the choices you repeat.
Frequently asked questions
- Does creatine make women look bulky or hold water?
- Creatine draws water into the muscle itself rather than under the skin, and the weight-gain effect reported in the literature is small. It does not produce a bulky look on its own — muscle is built by training and food over months, not by a supplement.
- Can you take creatine and protein powder together?
- Yes. They do different jobs: creatine supports high-intensity capacity and lean mass, protein powder helps you reach a daily protein target. There is no need to separate them or to time them precisely around a session.
- Is it better to take a pre-workout or just coffee?
- For the performance effect, the caffeine is the active part, and coffee delivers it. A pre-workout is more convenient for hitting a specific dose. If you use coffee, work out roughly what you are taking so you stay in a sensible range rather than guessing.
Sources
- Kreider RB, Kalman DS, Antonio J, et al. International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation in exercise, sport, and medicine. Journal of the International Society of Sports Nutrition, 2017;14:18. doi.org/10.1186/s12970-017-0173-z
- Guest NS, VanDusseldorp TA, Nelson MT, et al. International society of sports nutrition position stand: caffeine and exercise performance. Journal of the International Society of Sports Nutrition, 2021;18:1. doi.org/10.1186/s12970-020-00383-4
- Morton RW, Murphy KT, McKellar SR, et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. British Journal of Sports Medicine, 2018;52(6):376–384. doi.org/10.1136/bjsports-2017-097608
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Daphne Brands is an online fitness and lifestyle coach for women, and an active IFBB bikini competitor. She holds five certifications in coaching women’s training and nutrition. More about Daphne →