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The TRUTH About Diet Whey Protein’s

The popularity of whey protein powder as a sports performance supplement has grown exponentially in recent years. What was once perceived as a body-building aid used mostly by the male population, is now an integral asset to anyone working out – amateur or pro, male or female. The evidence supporting the use of whey for both enhanced performance and elevated recovery is undisputable – but with so many brands and varieties out there, purchasing protein powder can quickly become bewildering. Add in misleading marketing, questionable claims and ingredients lists as long as your arm, and you’ll quickly become confused. One of the best-selling whey protein powders are so-called ‘Diet Whey’ protein powders – but the question is – do they REALLY help you lose weight? Read on to find out…

What is Whey?

First things first, lets be clear on one thing – whey is a natural protein found in milk and it isn’t something created or invented by the fitness industry, but rather a substance derived from cow’s milk. Cow’s milk is made up of two proteins: casein and whey. Whey is typically formed as a by-product of the cheese-making process before being processed to remove waste products and produce a powder which is not only convenient to take, but is also contains all 9 essential amino acids – making it the perfect protein provision for your body to utilise for muscle metabolism and muscle protein synthesis (growth).

Diet Protein: Weight loss or Whey less?

Diet versions of whey protein powder are ever increasing in popularity and are often seen as the product of choice for those aiming to lose fat whilst maintaining muscle mass. But what exactly is the difference between regular and diet whey? Let’s start by taking a closer look at diet whey proteins, and what manufacturers are changing in order to call it ‘diet whey’. Thinking of diet foods and drinks, you would probably expect such products to be lower in fat, sugar, carbohydrate and calories – ultimately contributing less energy to your diet and so aiding weight loss. With diet whey however – the same logic isn’t always used.

All good quality protein powders should be naturally high in protein, whilst lower in carbohydrate and fat as a standard – it’s one of the most appealing aspect of them but by adding so-called fat burning ingredients or bulking agents – which fill-out the powder and make it cheaper to manufacture- you’ll often get an increase in carbohydrates and fat along the way. So in order to produce a protein powder which is cheap to make and allegedly ‘diet’ focused, ingredients are very often added. Things such as L-Carnitine, L-Glutamine and Green Tea Extract are added to the protein powder, and as if by some miracle – you suddenly have a fat burning, metabolism boosting protein powder. Or do you?

Curious Claims and Embarrassing Evidence: Why you shouldn’t always believe what you read.

In order to get past the fact that good quality whey is already ‘diet friendly’ anyway – in the sense that it’s high in protein and low in fat and carbs – manufacturers are adding other stuff to justify a ‘diet’ label. They argue that it’s worth the extra calories, fat and carbs in order to reap the benefits of the fat-burning ingredients as those ingredients are “proven” to burn fat.

Three of the most common ingredients often used in Diet Whey’s are L-Carnitine which helps the body use fatty acids for energy, L-Glutamine which helps to preserve muscle mass and Green Tea Extract which has been proven to boost metabolism. These are all true statements, supported by scientific studies and research so it must be worth taking on the extra calories, carb and sugar for these super ingredients – but the ONE thing that is CRUCIAL to these ingredients working is DOSAGE, otherwise they’ll not have the desired effect they’re marketed to. In the same way taking 1g of protein powder would never have an effect on the body’s muscle metabolism, unless you’re downing a tub of diet whey per day (which if you are please stop!) –  the amount of “fat burning” ingredients in a serving of diet whey is not worth having, as a serving size would not provide anywhere near the minimum effective dose to have an effect.

Adding the ingredients to the powder is merely a marketing ploy to justify the ‘diet’ label and is sadly misleading to customers who do not know any better. Our advice? Do your research – if your whey claims to be ‘fat-burning’ or ‘metabolism-boosting’ take a look at the ingredients, it won’t take long to find out their minimum recommended dose for effectiveness – and you can bet in almost ALL diet whey proteins this will not be reached.

To further expand on these claims made by diet whey manufacturers, we’ve focused on two ingredients commonly added to justify its fat-burning status: green tea extract and L-Carnitine. The market-leading diet whey product – PhD Diet Whey – contains both of these, and claims that they contribute to the fat-metabolising properties of their protein powder. But what about the dose? Is there enough of these ingredients to have an effect at all?

  • Green Tea Extract – catechins – natural phenols and antioxidants found in green tea have been shown to increase energy expenditure and fat oxidation in humans who drink green tea. This has can have a positive effect on weight loss. Evidence has shown the most effective dose of green tea extract for the body to utilise active catechins is between 400-500mg per day. Per serving, the market-leading diet whey contains just 100mg green tea extract. So not only would you need 5 servings of diet whey per day to get the effects of the catechins, but you could also get the same effect from a regular brew!


  • L-Carnitine – a relative of the B-vitamins, L-Carnitine is thought of as an ‘amino acid-like’ compound. A popular sports performance supplement, studies have shown that it functions within the cells to promote utilisation of fat over muscle mass for energy. This gives the compound it’s fat-burning, muscle-building reputation. Evidence shows L-Carnitine can be effective at a dose of 1g, but for maximum fat-burning effect it should be supplemented at a dose of 2-3g. The market leading Diet Whey contains only 125mg L-Carnitine per serving which of course – s far less than the minimal effective dose and worlds away from the optimum dose to burn fat. In fact, you’d need 16 servings of diet whey to reach the lower end of the optimum dose which is a whopping 1,456 calories!

If you’re on a diet and looking to lose weight, I’m sure this would be a huge disappointment – especially if you’ve been using a diet whey before. Whilst the fat burning ingredients may have a benefit towards dieting and weight loss, be aware that most manufacturers are adding them simply to draw you in – and not to give you the benefits or desired effect you’d expect from them.


Whey Protein Isolate for Weight Loss: Is This The Whey Forward?

We’ve covered ingredients, and how likely – or unlikely – they are to help you reach your weight loss goals, but what may be more surprising  is that four of the market-leading diet whey powders contain more carbohydrate, fat, sugar and calories than our whey protein isolate powder which makes ZERO claims about diet! AND, to make things worse – they also contain less protein (The nutrient with the most benefit to weight loss).

We’ve compared our Whey Protein Isolate with four of the most popular diet whey powders available and res serving – we’ve broken down the nutritional content of each below, and the results are certainly interesting. Here’s what we found…

  1. Diet Whey contains MORE calories than Natural Nutrients Whey Protein Isolate

3 out of 4 of the diet varieties we compared with our own whey contain more calories. One of the products contained fewer calories per serving than ours – but at a price of having far less protein per gram, and less than half the protein per serving! See below.


  1. Our Least Favourite Diet Whey contains more Carbohydrate, Fat and Sugar but less Protein than Natural Nutrients Whey Protein Isolate

Out of the four diet whey powders we compared with our own whey protein powder, we felt Matrix Diet Whey was the worst product. Take a look below to see how we compare. With significantly higher protein, and vastly lower amounts of carbs, sugar and fat, it’s easy to see that our whey would be the product of choice for weight loss.


  1. Even our Favourite Diet Whey was the Best of a Bad Bunch: Lower in carbs, fat and sugar but also – crucially – lower in Protein!

We found PhD Diet Whey to be the best of a bad bunch. Per serving it contains far less carbohydrate, sugars, fat and calories than its rival diet whey powders. BUT, this comes hand-in-hand with the fact that the protein content of PhD Diet Whey comes in at 0.7g per gram, compared with 0.9g per gram you’d get with Natural Nutrients Whey Isolate. The less protein per gram, the more added ingredients used to bulk-out the product – which is why over 90% of our powder is pure whey protein.

We hope to have given you an insight into the world of so-called ‘Diet Whey’ and its potential downfalls. When choosing a protein powder to supplement your diet and enhance your performance, we’d recommend being cautious about added ingredients and claims such as ‘fat-burning’ and ‘weight-loss formula.’ Our ethos is to use the best ingredients and create products which are natural, reliable, effective and evidence-based. We use Natural Whey Protein Isolate which is non-denatured, giving you maximum protein content per serving. And because we don’t add any unnecessary ingredients or bulking agents, our product is naturally low in fat, carbohydrate and sugars. Lower, it seems, than it’s ‘diet’ rivals! So you can have faith that our Whey Protein Isolate is as clean as possible, as well as tasting great and ultimately helping you to achieve your health and fitness goals!


Stephanie Masterman




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