Meal Replacement Shakes: Do They Actually Work? An Analysis of 23 Studies Answers

Pharmacy shelves are full of them and their promises are enormous. Let's put them under the largest available analysis.

The analysis

A systematic review and meta-analysis covered 23 studies and 7,884 adult participants, comparing meal replacements with other interventions^[1]. In 15 studies (65%) the replacements were specially formulated shakes, soups or bars^[1].

The result

In studies with similar interventions, mean weight change at one year favoured the meal replacement group by −1.44 kg compared with controls^[1],[2].

And when do they work best?

Another review found that low-energy diets based on meal replacements were superior to food-based low-energy diets, and that obtaining 60% or more of total daily energy from replacements produced the largest effect on weight loss^[3].

But read the number critically

1.44 kg over a full year — a real but modest effect. And evidence quality varies: only 6 of 23 studies were rated at low risk of bias across all domains, and 5 at high risk in at least one domain^[1]. Note too that many of these studies are funded by product manufacturers — a legitimate consideration when reading them.

Who might they help?

• People with genuinely no time for breakfast — a counted replacement beats a station croissant.
• People who fail at portion estimation: a replacement comes with precisely known calories (the accuracy problem).
• A short launch phase to build momentum.

And who they don't help

• Anyone expecting magic: 1.44 kg in a year is not a transformation.
• Anyone who learns nothing alongside them: if you return to old habits after stopping, the weight returns (maintenance habits).
• Anyone on a tight budget: two eggs and a slice of bread are cheaper and more satiating (the satiety index).