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What Actually Makes a Supplement ‘the Best’? Category-by-Category Criteria for UK Buyers (Testosterone, Pre-Workout, Fat Burners, Creatine & More)

13 Oct 2026
What Actually Makes a Supplement ‘the Best’? Category-by-Category Criteria for UK Buyers (Testosterone, Pre-Workout, Fat Burners, Creatine & More)

Potency, purity, potential side effects – that’s the three top Ps that make supplements “the best”. However, what’s good for one doesn’t have to work for the other. You have to factor in your individual goals when picking supplements. Learn more!

Key Takeaways

  • Regular criteria to look for in every supplement include purity, manufacturing standards, and potency based on your goals & experience.
  • For each supplement, you take a different angle – the best is one that dominates in a niche of specific properties that match your lifestyle, health and purposes.

Criteria for testosterone boosters

With testosterone boosters, we know the science – what ingredients work, and which aren’t confirmed. So, naturally, this is one of the first points to look at. However, since you want to raise your hormone levels, the case gets tricky. You can’t buy every good formula – you need to consider your starting point and goal to ensure you don’t over- and under-do this hormone. Here are the key criteria for choosing testosterone boosters.

  • Researched formula – ingredients backed up by science.
  • Potency – based on your current testosterone levels; it might be a good idea to test your testosterone concentration beforehand.
  • Potential side effects – the fewer, the better.
  • Purity of the ingredients – usually confirmed by GMP or other certification.

Criteria for pre-workouts

The main choice in pre-workouts is between stim and non-stim – this depends on:

  • whether you tolerate caffeine,
  • when you work out during the day.

Stim pre-workouts might make it difficult to fall asleep if you train in the evening, but they are good to go for afternoon or earlier training sessions.

Once you have made your choice between stim and non-stim, you have to pick potency. As a rule of thumb, don’t overdo it – as long as a pre-workout gives you an energy & concentration boost, it’s fine. If you feel it isn’t doing the trick, switch to a more powerful one.

Criteria for fat burners

Fat burners also vary, and you’ve got a few options to choose from. What makes a supplement like that the best? Mainly, an effective formula that indeed does help you drop weight… while also preserving muscle mass. Additionally, good fat burners:

  • might contain stimulants – in this case, avoid taking them with stim pre-workouts,
  • suppress appetite – making sure you not only burn more, but also eat less.

Of course, purity and the potential for side effects also apply here.

Criteria for creatine

What makes a creatine supplement the best? First is the form: monohydrate is considered the most effective, so opt for that if possible; on the other hand, alternative forms might be best for those with sensitive stomachs.

Once that choice is made, all the standard criteria apply, plus… the flavour. You take creatine every day, so even if flavours don’t affect your workout, it’s still better to get something you like, isn’t it?

Bottom line

What makes the best supplement? Purity, quality and a plethora of other criteria based on the type of product you’re going to buy. Always adjust the criteria based on your experience, goals and current health state – there’s no Panacea that will be the best for everybody!

FAQ

How do I accurately test my baseline testosterone levels before choosing a testosterone booster?
With a blood test taken in the morning, since this is when your testosterone levels peak.
Can I stack a non-stimulant pre-workout with a stimulant fat burner?
Yes, you can. Don’t stack two stimulant supplements together, but if only one is stim, you’re usually free to go.
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