A popular weight loss shake, Diet Fuel (produced by USN) has been on the market for years now. The formula has undergone multiple revisions – in this USN Diet Fuel Ultralean review we’re looking at whether the most current version is truly good for weight loss.

Readers please note that statements on this page are fair comment based on observation. This content is produced on a matter of public interest. Statements on this page are our honest opinion, not fact. Let’s take a look at the top level pros and cons of this product:

USN Diet Fuel Benefits:

  • Low calorie content
  • Contains protein
  • Multiple flavor options

USN Diet Fuel Drawbacks:

  • No ingredients used inside have any solid evidence to suggest they burn fat
  • No real long-term appetite suppressing ingredients inside the formula
  • Some users have stated the taste and texture of this shake are bad
  • No money-back guarantee

usn diet fuel review

Editor’s note: Shopping around? Click here to check out our most recommended shake for weight loss.

Some Quick Information About Diet Fuel Ultralean

Diet Fuel Ultralean is a Meal Replacement Shake produced by USN (Ultimate Sports Nutrition). In true USN style, the product is priced at the top end of the market sitting at £31.99 per kilogram. You may be wondering if the high pricetag reflects the quality of ingredients inside? Well, we found that that’s not really the case.

The formula to this product is actually pretty simple; it’s simply a blend of whey protein, calcium caseinate and soya protein mixed with some CLA, and L-Carnitine. There really is nothing groundbreaking about this formula – there are no scientifically proven fat burning or appetite suppressing ingredients inside, which is disappointing to see.

The general idea of this product is that users will replace their three daily meals with a 55g serving of Diet Fuel. This means you’ll be consuming 165g of powder per day, making the 1KG tub last just about 6 days. As you’ll need to use this product for at least two months to really see any noticeable weight loss, this can be a pricey endeavour!

In replacing your three daily meals with Diet Fuel Ultralean you’ll be putting yourself on a diet what is medically known as a VLCD (which stands for Very Low Calorie Diet). This is how you lose weight with Diet Fuel Ultralean, not the ingredients burning fat.. but rather the fact that you’re significantly lowering your daily calorie intake.

Does USN Diet Fuel Work?

We do not think this is a good product for long term weight loss success. VLCD’s are basically just a crash diet; essentially you’re starving the weight off your body. Once you discontinue using USN Diet Fuel you’ll probably see the weight loss quickly return.

As we mentioned above, this product does not contain any metabolism boosting, fat burning or appetite suppressing ingredients. For a product with such a high price tag we’d really expect to see at least a few powerful ingredients inside.

The main issue with VLCD is that when your body goes into starvation mode metabolic rates grind to a halt meaning that weight loss can actually be slower. When you consider that you’ll probably be feeling very low on energy and ravenously hungry all the while sticking to the Diet Fuel shake diet, it hardly seems worth it.

If you’re looking for a diet shake that will help you burn fat and spare muscle mass, this shake probably isn’t the best choice for you.

What Are The USN Diet Fuel Ingredients?

We have found the following ingredient information on the Holland & Barrett website:

One Serving Contains: Whey protein (Milk), calcium caseinate (Milk), soy protein isolate and egg albumin powder, Maltodextrin, MCT (Medium Chain Triglycerides), Cocoa powder, CLA (Conjugated linoleic acid), L-Carnitine, Boron, Selenium, Fructose, Calcium Phosphate, Sodium Chloride, Aspartame (sweetener), Stabiliser, Vitamin Blend, Chromium Picolinate, Flavourants.

Allergens – contains milk, soy and egg.

What Are The USN Diet Fuel Side Effects?

The side effects for this product could potentially be:

  • Increased bowel movements
  • Flatulence
  • Stomach discomfort
  • Nausea
  • Increased thirst
  • Bloating
  • Cramps
  • Headache [1][2]

Note: these side effects are possible but may not be the typical user experience.

What does USN Diet Fuel claim to do?

USN don’t actually make any hard weight loss claims about Diet Fuel, despite the product name heavily suggesting it causes weight loss.

The only thing we could find was:

A great tasting, meal replacement shake for those wanting to shed those extra pounds.

While this statement is fair enough, it doesn’t exactly emphasise the point that users will need to replace their meals over a sustained period of time to see any results.

Are There Any Reviews From Customers?

We have found the following USN Diet Fuel Ultralean review testimonials:

Style: Powder | Flavour Name: Chocolate Cream | Size: 2 kg|Verified Purchase
Rubbish , rubbish , rubbish !!
Bought twice and putting weights on, not sure if it’s truth reviews on here… doesn’t keep you full neither don’t buy

Style: Powder | Flavour: Chocolate Cream | Size: 1 kg|Verified Purchase
For those who say that you don’t have a scoop,look inside the powder.Mine is blue.
Regarding the taste for me it’s awful. I tried to mix it with water and milk but I still can’t drink it and I also have a problem with the consistency.
After you drink it, you really feel full but with me it was that after 2-3 hours I got extremely hungry.
I had high hopes with this meal replacement but now I’m just very disappointed.

It seems that a lot of people mentioned that the product doesn’t leave you feeling very full. This is testament to the complete lack of appetite suppressing ingredients used.

Where Can I Buy This Product?

You can buy Diet Fuel in most sports nutrition stores and on the official USN website. You can also get the product on eBay and Amazon.

Our Conclusion.

To conclude our USN Ultralean Diet Fuel Ultralean review, it’s a bit of a mixed bag – there are things that we like about it and things that we aren’t too blown away by to our readers. It’s not a terrible product by any meals – USN are a pretty reputable company, albeit expensive. We just think that the formula is too lacklustre and the price-tag is way too high for what is essentially just a protein shake with a few added extras. There are no fat burning ingredients, so any weight loss with this product will be from a general lowering of calories – that could be a positive for some people and a negative for others.

As these shakes put you on a VLCD, you’ll probably find yourself low energy and hungry for the duration of your shake-only diet. If you are going to use this product, we’d advise you stick to a low carbohydrate diet while supplementing the shakes to replace one or two meals – ensure you’re actively exercising to get the best weight loss results.

Kath Ross, PhD
Kath Ross, PhD
Health Editor at DietProbe
Kathryn is a Ph.D Health Editor here at DietProbe. She specializes in diabetes and weight control research and in her spare time she's a professional cat lady and wine connoisseur!
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