Most meal replacements are used for weight loss purposes, and they are incredibly effective for this. Several studies have found meal replacement shake diets to be more effective than regular calorie deficit diets.
A 2003 study in the Journal of Obesity found that subjects who followed a partial meal replacement diet (1 or 2 shakes per day) saw significantly more weight loss than subjects who followed a regular diet. Averaging a 7-8% loss in body weight compared to a 3-7% loss [1].
After three months the average weight loss for subjects on a partial meal replacement diet was 2.54 kg greater than that of regular dieters.
One of the most common theories as to why meal replacement diets are more effective than regular diets is that people are bad at estimating calories. A 1992 study found that obese people underestimate their calorie intake by around 40-50% [2].
This is completely understandable, calorie estimation is very difficult, and it is tempting to discount calories or underplay their importance. Forgetting to calculate the calories in the oil you cooked your food in, for example, is common. But this represents 100-200 calories per meal!
Meal replacement shakes take away this issue. Rootana is 400 calories per 100-gram serving. You can’t underestimate the calories for that, and you are less likely to accidentally end up in a calorie surplus when your calories are planned out in advance.
A 2012 study by Tsai & Wadden postulated that one reason for the success of meal replacement shake diets is simple to follow [3].
“Obese individuals typically underestimate their calorie intake by 40% to 50% when consuming a diet of conventional foods because of difficulty in estimating portion sizes, macronutrient composition, and calorie content and in remembering all foods consumed. Meal replacements seem to decrease these difficulties and simplify food choices”
Instead of having to change all three of your main meals, you only have to change one, while the other two are replaced by a meal replacement shake that provides you with protein, fibre, and essential vitamins and minerals.
“Meal replacements (liquid or solid pre-packaged) provide a defined amount of energy, often as a formula product. Use of meal replacements once or twice daily to replace a usual meal can result in significant weight loss.” American Diabetes Association position statement (2008) [4]
Another benefit is the lack of variety available. This sounds backwards, but having fewer options to choose from has been found to reduce your desire for unhealthy snacks or overconsumption. A 2006 study placed overweight people into two groups: one group ate the same snack for eight weeks, while the other was allowed more variety.
While both groups reported weight loss, the group with no variety saw improvements in satiety and a reduction in pleasure in eating the snack [5]. This sounds like a bad thing, but when on a diet, lowering the pleasure you take in snacking is important, as it helps you to stay on the diet.
Where meal replacement shake diets stand out from the competition is in their longevity. There are diets that can be just as effective in the short term, but very few people are able to follow them for longer than 2-3 months.
According to WebMD, the average amount of time that people stay on a diet is six months [6]. However, the stricter the diet, the shorter it lasts. This is one of the biggest issues with dieting, and it is an area that meal replacement shakes excel at addressing.
Meal replacement shake diets outlast almost all other diets, due to their convenience, the lack of preparation required, and the relatively low price per serving (compared to some diets such as paleo or keto).
As a 2012 study in the Journal of Obesity Research put it:
“However, the patients in this study who dropped out for several months then re-entered the program had not gained weight. The convenience and low cost of meal replacements compared with usual higher calorie meals may have favourably influenced their eating patterns.” [7]
To put this quote into context. One of the biggest problems with nutrition studies is that people fail to continue (for the many reasons we have mentioned).
This study was no different, however, the patients who had left the study and returned had not gained weight, because they were able to follow the diet on their own.
Bottom Line: There are hundreds of long-term studies that have shown meal replacement shake diets to be more effective for fat loss than regular diets [8][9][10].
This is due to the diet being easy to follow, convenient, and cost-effective. Meal replacement shakes provide a satisfying and calorie-controlled meal option that is unlikely to result in overconsumption, making it perfect for anyone struggling with their weight.
