I'm A Nutritionist – Here's The Truth About Your Protein And Meal Replacement Shakes

Let’s be real – when you’re in a hurry, or even on a diet, reaching for a meal replacement shake can seem like an easy answer.

And those green, vanilla or chocolate meal replacement shakes can taste seriously nice, but as a nutritionist with over 20 years experience, I’ve got some brutal news for you.

The reason they taste so good is because they include plant-sweeteners that are up to 350 times sweeter than sugar and can increase the risk of type 2 diabetes and other serious health conditions according to a recent declaration by the World Health Organisation (WHO).

It’s not just that – these shakes are missing a whole lot of other really important things for your gut and overall health.

Let’s dive in. 

Why are sweeteners so bad for us?

The consumption of plant-sweeteners and artificial sweeteners has been a concern for a long time given their increasing use in weight loss foods and drinks, meal replacement, and supplement shakes.

The debate culminated in May 2023 with the WHO announcing that after extensive research using sweeteners “does not confer any long-term benefit in reducing body fat in adults or children” and, worse still, “there could be ‘undesirable effects’ such as an increased risk of type 2 diabetes, cardiovascular diseases, and mortality in adults.” 

While sweeteners do not contain the calories of sugar, studies shows they can directly and indirectly through our gut bacteria trigger higher levels of insulin in our body. Too high levels of insulin can lead to ‘insulin resistance’, also known as pre-diabetes, and type 2 diabetes, increasing the risk of other health conditions, including cardiovascular disease.

The sweeteners the WHO is referring to include those found in the best-selling meal replacement and protein shakes which have become a popular fad, including stevia and stevia derivatives, saccharin, sucralose, aspartame, advantame, cyclamates and many others.

Why did the WHO act? One reason is that companies proudly say on their pack ‘No artificial sweeteners’, yet their products contain high levels of plant-sweeteners which are shown to be at least as bad as sugar and artificial sweeteners for increasing the risk of type 2 diabetes and other health conditions.

What are some of the wider issues with meal replacement shakes?

Missing nutrients

As idealistic as it may sound, meal replacements should not be relied upon as an alternative to food, especially in the long term. Many nutrients in food are not classified as ‘vitamins’ or ‘minerals’, and therefore not included in meal replacements.

These nutritional compounds include phytoestrogens, fatty acids, flavonoids, anthocyanidins, carotenoids and many other compounds which are needed for our optimal health, but are all missing from meal replacements. When only meal replacements are consumed, your body will lack all these vital health-promoting nutritional compounds.

Decreased chewing

Chewing food has important biological functions, including stimulating the production of digestive enzymes and telling your body there is food coming.

Digestive enzymes ensure that food substances and nutrients are broken down properly for optimal gut health - our gut is our ‘second-brain’, connected to our brain by the ‘gut-brain axis’, so our diet and our gut are the starting point for all health goals. Chewing is also important for the release of stomach acid. If your stomach acid is too low, you can find yourself with indigestion and other gut issues, including bloating.

If you have gut health issues, it’s advised to avoid drinking liquids at meal times and to avoid liquid meals such as shakes, soups and meal replacements so you don’t dilute your stomach acid further. Chewing food also helps you to feel full, so if weight loss is your goal, make sure you eat food (and chew as much as you can) and steer clear of powder supplements and meal replacement shakes.

Where’s the fibre?

Although some meal replacements and powder supplements add fibre, the majority do not, or they do not add enough fibre. A healthy diet contains lots of fibre, both soluble and insoluble, and this is necessary for the health of your gut and to aid the body’s natural detoxification process.

A homemade smoothie, for example, contains the fibre from the fruit or vegetables added. Unfortunately, this freshness is very hard to add to a meal replacement or powder supplement because it needs a long shelf life. It is just as important to look at what you are not eating as it is to look at what you are eating.

Overly processed

Unfortunately, all powder supplements and meal replacements are very processed. They have long shelf lives and generally contain artificial ingredients to add flavour and create long shelf lives to be shipped across the world.

Where possible, it is always best to consume food in its unprocessed form, and your food should be as close to its natural state as safely possible to gain the full benefit.

Supplement expert Shona Wilkinson is a member of both the Royal Society for Medicine and the Professional Association for Nutrition and Lifestyle Medicine and lead nutritionist at DR.VEGAN.