The gainer market is literally and literally oversaturated with supplements of considerably shoddy quality. They usually contain a huge amount of simple sugars and a minimum of quality protein, and therefore they are demonized by many athletes. Still, there are supplements that have something to offer.
And one of them, in our opinion, is One Stop Xtreme, which we've taken a look at in our review today. What do we think makes it stand out? How does it taste and who do we recommend it to? Find out in the following test.
Content of the review
At the beginning it remains to add that One Stop Xtreme became the winner of our ladderof the best gainers, so today you'll find out how it stands out from the competition.
Ingredients that definitely don't deserve criticism
As I already mentioned in the introduction, the composition of various gainers is often the target of criticism because it contains unnecessary amounts of of simple sugars, unprofitable proteins and often nonsensical mixtures of vitamins, how else but in the cheapest forms. What bothers me, however, is when someone lumps all products together, because One Stop Xtreme certainly doesn't deserve it. Take a look at its ingredients:
- 42% protein blend, in which you'll find both whey concentrate and native milk protein, which is furthermore a source of micellar casein. The two types of protein with different absorption times are a very good choice after a workout, as they ensure the supply of amino acids for a longer period of time.
- 20% of the carbohydrate blend, which is made up of a combination of barley and oat flour. No sugar, no glucose-fructose syrup or anything like that, just quality complex carbohydrates.
- Maltodextrin, with its glycemic index just above simple sugars, can be justified after training not only for glucose replenishment.
- The mix of amino acids and micronutrients is usually a stumbling block, as manufacturers will use the cheapest possible ingredients. But in One Stop Xtreme you will find 3g of m-tor leucine, which is used to start proteosynthesis, minerals in the form of bisglycinate (zinciron and copper), B vitamins indispensable for athletes, vitamin C, creatine and other great ingredients
- Steviol glycosides and sucralose are of course the best possible choice, as they are much less harmful than such cyclamate or the controversial aspartame.
As you can notice, the composition is really top-notch and there is nothing to fault it. I personally have to highlight the probiotic cultures and digestive enzymes, which really help to improve the digestibility of the product. Reflex has thought so much about making the best use of the other ingredients that it uses black pepper extract, which is known to increase the absorption of some substances by up to 3000%.
It is necessary to use half the dose
When you look at the recommended dosage of the original UK version, you may well drop your chin. You should in fact, according to the manufacturer, use 145g of One Stop Xtreme twice a day. I, of course, modified this amount and used only 70g after training to supplement my calorie intake.
I have to admit that this amount combined with 250ml of water was completely sufficient for me, and therefore I recommend the same procedure to you. The Gainer dissolved in the water without any problems, did not form lumps and did not foam in any way, so it was ready to drink within seconds.
The chocolate variant is surprisingly not very good
The number of gainers I've tried in my lifetime could probably be easily counted on the fingers of one hand. Even so, I had a fixation on them that their taste is very good, at most they seem a bit more sweet than would be ideal. Unfortunately, One Stop Xtreme falls rather short. So it's not over-sweetened, which I certainly appreciate, but otherwise there's really not much to praise. It smells and tastes pretty artificial and despite the poetic label of the flavor "Chocolate Perfection," the gainer is definitely far from perfect.
Personally, I would expect that if the manufacturer is not limited to the lowest amount of carbohydrates, it canuse even better flavoring ingredients - such as chocolate, bitter cocoa, etc. Reflex uses only cocoa powder, which unfortunately who knows how miraculousIt doesn't conjure up the most wonderful taste, which is why I give this flavour only 6.5 out of 10 points.
Unfortunately, the excellent formula is offset by the price
While the price of most protein supplements is around per dose, One Stop Xtreme is based on if you use the dosage recommended above. If you were to stick to the UK's hardcore dosage, you'd pay for one dose right away at , which is already a really unimaginable price. So unfortunately in this case, you' ll have to pay extra for a quality gainer.
Final evaluation
If you are not able to gain weight and you need it badly, you need to eat more in the first place and choose more calorie-dense foods that are guaranteed to help you do that. But if you're doing the best you can, a gainer may be a good choice. And if I were to consider buying a gainer, it would definitely be One Stop Xtreme.
Less than two grams of simple sugars per 100g, perfectly chosen functional ingredients and what's in it for gaining most importantly, a good dose of calories that will reliably increase your daily intake. So this gainer is definitely not essential, but if you're really struggling to put on weight, it can definitely help.
Read on: A selection of the 10 best gainers on the market 2026!
Comparison with competitors
Other expert reviews
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- GymBeam [review]: low quality protein True Whey, Just Whey
- Optimum Nutrition Whey Gold Standard [review]: the gold standard among whey proteins
- Scitec 100% Whey Professional [review]: one of the most popular proteins
- Nutrend Protein [review]: just another lure for money?