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A pouch of The Define Booster - acetyl l-carnitine supplement by Innermost
A pouch of The Define Booster - acetyl l-carnitine supplement by Innermost
A pouch of The Define Booster - acetyl l-carnitine supplement by Innermost
Ambar Driscoll smiling and looking confident for Innermost
Pouches of The Define Booster - acetyl l-carnitine supplement by Innermost
The Define Booster white powder - acetyl l-carnitine supplement by Innermost

The Define Booster

Definition done properly.

To decrease body-fat you need the right nutrients. That’s where this product comes in. The most popular non-stimulant fat-loss supplement in the world. It works by ensuring your body is metabolising fat efficiently. Live life in High Definition.

The Define Booster

Unflavoured with a slightly bitter taste | 200g

£24.95 £24.95

Product Highlights

Active Ingredients

For every serving of The Define Booster: Acetyl L-Carnitine (2g).

Scroll down to learn about these ingredients and how they benefit you.

How And When To Use

To be taken during the day, once a day.

Directions: Mix 2g (1 flat teaspoon) with around 200ml water or juice in your Innermost shaker bottle, or simply add 2g to your pre or post-workout protein shake. Unflavoured acetyl l-carnitine does have a bitter and citric taste so mixing it with orange juice or lemon water works well.

Works Well With: The Tone Capsules to raise your metabolism and support healthy fat-loss.

User trials

*Results based on 59 participants surveyed over a 30 day period. Participants were requested to log a diary and complete a survey at the end of the month.

I’ve never been able to see muscle definition…

Gaining definition can seem like an unattainable goal.

But it doesn’t have to be. If you’ve been working hard to see results, and just want an extra push in the right direction, then look no further.

The Define Booster is one of our most popular products for a reason. Formulated by leading nutritionists, it's been crafted to metabolise fat for energy, support endurance, and even boost memory and learning. Start seeing the lean muscle definition you’re looking for. Because reaching your fitness goals doesn’t have to be impossible.

Do I have to take it alongside a workout?

You don’t have to be working out to take The Define Booster - you can take it whenever you want, even on non-workout days.

What does The Define Booster taste like?

The Define Booster has a tart, almost citrusy flavour (naturally). Think lemon water.

Can I mix it with other products?

You can absolutely take The Define Booster alongside any other Innermost product, though due to its tartness we’d recommend having it separately in a glass of cold water with a squeeze of lemon juice.

Innermost is awarded The Game Changer Award. The sands are shifting in the supplements industry. One brand stands out most, Innermost. We now expect more from our supplement products and Innermost is well ahead of the curve.

Ingredients backed by science


With so many “miracle” ingredients being touted out there, it can be hard to know what really works. We believe evidence-based ingredients are the best way to better health. With decades of clinical studies showing how the active ingredient in this product can encourage the metabolisation of fat during physical activity, ensure efficient use of energy, and help improve tone and definition, we're confident that you’ll thank us later.

Per Serving:

Acetyl L-Carnitine

Acetyl L-Carnitine (2g): One of the most popular non-stimulant fat-loss supplements on the market today. A non-essential amino acid found naturally in the human body, necessary for transporting fat to the body’s power-generating mitochondria for use as energy during physical activity. Without carnitine, we wouldn’t be able to use fat effectively as a source of energy, which could result in the body having to break down muscle instead. The key benefit of the acetyl form of carnitine is that it can cross the blood-brain barrier to improve mood, learning and memory as well. References > 1, 2.

Allergens: None. 

Learn More:  6 Habits to Melt Fat Fast
Learn More:  5 Reasons Why You Aren't Getting Leaner

Why it's special

Acetyl L-Carnitine

Acety l-carnitine is a substance natural to the body that serves an important role in the burning of fat for energy, and ferrying fatty acids across the walls of the mitochondria, where they are oxidised and turned into energy. On its return trip from inside the mitochondria, it brings back acetyl groups and other small fragments produced in fatty acid oxidation. Carnitine's role in fat metabolism leads it to affect, in some degree, all the other energy metabolism in the cell, including the burning of carbohydrates. Some researchers have suggested that its important role in the burning of fat also makes it useful in diets for weight loss.

When should I use the product?

The Power Booster anytime during the day or before your workout.
The Energy Booster right before and/or during your workout.
The Detox Booster works well as a morning/afternoon pick-me-up.
The Define Booster anytime during the day but morning works well.

How many servings do I get?

Based on taking each product every day as recommended:

The Power Booster will last 60 days.
The Energy Booster will last 30 days.
The Detox Booster will last 60 days.
The Define Booster will last 100 days.

Can I mix and match products?

Yes, absolutely. We developed all our products so that you can mix and match any of them depending on your individual goals and needs. You will get the benefits of each of them regardless of whether you're taking them alone or with any of our other products.

What sort of testing do you do?

We go over and above to ensure you get the best quality and safest products possible. We only use ingredients that have a visible supply chain, and our manufacturing facilities are approved to the highest regulatory standards. Once we receive ingredients, we batch test every single one before it gets approval to go into the manufacturing process. That isn’t technically an official requirement but it’s something that we think should be.

Real People, Real Results

Customer Reviews

Based on 17 reviews
Chloe Elliott
Great product!

I have had so many mixed experiences buying l-carnitine, where it comes crystallised or is just ineffective. This is one of the best I have tried. Effective, beautifully soft, easy to mix powder and most importantly, great results!

Great product to mix into smoothies

Great product, doesn't taste brilliant on it's own but it's easy to mix into smoothies and porridge.

Strange but good!

I weirdly love the taste of this - it’s very bitter, exactly like a big squeeze of lemon juice in a glass of water. I have it first thing in the morning and it wakens my taste buds. I’m not hugely aware of losing weight or becoming more defined with it but I’ve added it in to my fitness regime and overall I’m seeing differences.

Not sure

I'm not sure about this one. Although if I'm honest I don't take it daily. I have it with my protein shake which is every second day. I am very slowly getting toned but I think that's simply down to the fact that I'm finally moving after months of not. The taste is quite pungent and in the pack reminds me of salt and vinegar crisps, but hides well in the shake.

Lara khosla
Gives an energy boost

Have it first thing in the morning in a glass of cold water !
It's a strong taste but seems to be working :)

Joanne Taylor
Strong taste - very bitter

Too early to tell if this product is beneficial. Seems good value for money though, and it's easy just to fix up as a quick afternoon boost. It tastes like a salty lemon, but a quick shot is easily done.