Meal replacement drinks: explainer
- Meal replacement drinks provide convenience and can deliver complete nutrition
- Fully liquid diets are not inherently harmful for everyone
- Nutritional adequacy requires sufficient calories alongside vitamins and minerals
- Satiety depends on fibre, protein, texture, eating speed, and energy
- Long term exclusive use may require individual dietetic assessment
Meal replacement drinks are often marketed for their convenience.
Brands such as Huel and Yfood promote their drinks as ‘nutritionally complete’ or as a ‘complete meal’; essentially, a replacement for parts of a diet.
In a world where consumers increasingly demand convenience (in fact, convenience was seen as a trend across Europe even where other eating patterns diverged), such drinks provide a valuable alternative to meals.
They can replace a significant amount of a consumer’s diet. But how far can consumers take this?
Liquid diets are not ‘inherently harmful’
While “an everyday meal replacement shouldn’t automatically be assumed suitable as someone’s sole nutrition”, an entirely liquid diet is not “inherently harmful”, says specialist dietician Nichola Ludlam-Raine.
In many ways, liquids can do the same job as solids when it comes to nutrition. Whether nutrients are absorbed does not depend on whether they are solid or liquid, but rather on their chemical form, their preparation, and what accompanies them.
Importantly, solids are not medically essential for everyone, Ludlam-Raine points out, and those who cannot eat them can often get by on a fully liquid diet.
The picture remains nuanced
If a consumer decided to replace a solids diet with meal replacement drinks, the impact is nuanced.
“‘Nutritionally complete’ needs context: complete at what daily intake, and suitable for whom?” asks Ludlam-Raine.
Calories are particularly important: one must ensure that they are getting the right amount of calories from these drinks as well as the right amount of nutrients.
“Calories are themselves part of nutritional adequacy: meeting vitamin and mineral requirements doesn’t compensate for inadequate fuel.”
A sustained and excessive energy shortfall can lead to fatigue, loss of muscle and poorer recovery. Low energy availability can even affect reproductive function and bone health in active people.
Furthermore, a diet of meal replacement drinks could, depending on the composition, affect gut health, Ludlam-Raine says, although this is far more dependent on fibre amount and type, and the tolerance of the individual in question, than on the fact the diet is liquid.
Some studies on exclusively formula-based diets show changes to gut bacteria and bowel habits, influenced by added fibre. But, Ludlam-Raine points out, changes to the microbiome do not inherently mean harm.
Finally, while a meal replacement drink may contain the nutrients one needs, it “may not reproduce the range of fibres, plant compounds and food structures found across a varied diet”.
Do meal replacement drinks satisfy hunger?
Consumers do not only eat in order to get the right nutrients. They also eat to stop feeling hungry.
Around 31% of consumers see a beverage as a snack when it’s filling enough, explains Marieke Bokkes, market analyst at analytics company Innova Market Insights.
And consumers want these drinks to play the role of snacks, at least in terms of satiety. “Drinks are being judged on hunger now, not just refreshment,” says Bokkes.
Is it possible that meal-replacement drinks can satisfy these demands for satiation?
The short answer is yes. Meal replacement drinks “can be filling, particularly when they provide adequate energy, protein and fibre”, says Ludlam-Raine.
Yet satiety is complex. “Fullness involves several signals: stomach stretching, nutrients reaching the intestine, gut hormones, texture and eating speed.” Therefore, results can vary.
A food’s physical structure can influence digestion and fullness, and for some, chewing and food forms can influence appetite. Some studies have found liquid meals less satisfying than their solid equivalents.
Yet “it’s too simplistic to say that drinks cannot satisfy hunger or that volume alone controls satiety”, says Ludlam-Raine.
How long can consumers replace food with drinks?
There is no defined upper-limit to how long a consumer can maintain a diet of meal replacement drinks instead of food, says Ludlam-Raine.
Medically indicated formula feeding can, she says, go on for long periods as long as it is monitored.
However, this does not mean that replacing a diet with meal replacement drinks is simple or easy. “I wouldn’t recommend indefinite exclusive use of an everyday consumer shake without individual dietetic assessment.”
Responding to consumer needs
Meal replacement drinks can go a long way in responding to consumer needs, not only in terms of convenience – replacing nutrients they would otherwise only get from food – but satiation as well.
Ultimately, the drinks are best viewed in the way that they’re marketed: capable of delivering nutritional value and satiety, but remembering the nuance of individual requirements and responses if they’re heavily used as meal replacements.
