Can You Live On Meal Replacement Shakes Alone?

By Matt Smith

Published: April 9, 2025

Many people now realise just how beneficial a meal replacement shake can be. Most people who purchase meal replacement shakes will have them once per day. Some may have them twice. But can you live on meal replacement shakes alone?

It is certainly possible to live on meal replacement shakes alone, and there have been many studies in which this has occurred. However, it is not advisable to do this for too long, and most people would find it an unpleasant experience. Once or twice per day, alongside healthy meals and snacks, will provide better results.

In this article, we will take a look at the positives, and the negatives of living off meal replacement shakes and nothing else.

What are Meal Replacement Shakes?

Meal replacement shakes have been around in one form or another for decades. While some people trace meal replacements back to the Native American food called Pemmican, the first meal replacement shakes that we would recognise today came around in the 1960s.

While there were a number of shakes that promised to replace meals, they didn’t become mainstream until the 1980s when SlimFast became hugely popular.

Other meal replacement shakes came out, with Herbalife being one of the most famous, or should we say infamous?

It is interesting how the public’s perception of what meal replacement shakes were designed for has changed since the first meal replacement. Pemmican was a bar made up of calorie-dense ingredients and was designed to help you survive when food was scarce.

In the early 20^th century, before commercial meal replacement shakes even existed, the idea was to use meal replacement shakes as a way to save time and effort. Rather than as a way to lose weight. By the 1980s, products such as SlimFast were designed to encourage weight loss, and this stayed the same until very recently.

Today, meal replacement shakes are designed to improve your nutrition and replace unhealthy, expensive, time-consuming meals. You can still use them for weight loss. You can even use them in the same way that Native Americans used Pemmican.

A meal replacement shake is any liquid or powdered food that can replace a meal. That’s a very broad definition, and it has a lot of grey areas (soup is not a meal replacement, but it fits the definition). They are usually high in protein but also contain fats and carbohydrates.

Not all meal replacement shakes fit this definition, though. Some are keto-friendly and contain little-to-no carbs, while others can be very low in fat. But they differ from protein shakes as they provide a more balanced macronutrient ratio.

Can You Live On Meal Replacement Shakes Alone?

From a purely scientific point of view, you can, of course, live on meal replacement shakes alone. Most shakes contain 400 calories, and you could have 5 x 400-calorie shakes for a total of 2,000 calories. You could use them to maintain your weight, lose weight, or gain weight.

The real question is not whether you can live on meal replacement shakes alone but whether you should. That is a much more interesting question.

The average calories needed for a man is around 2,500 calories per day, while a woman needs around 2,000 calories per day. Unless you are looking to lose weight, it would be difficult to hit your calorie target with meal replacement shakes alone.

A man would need to take over 5 servings per day just to hit their maintenance target. While there have been many studies on meal replacement shakes that involved people taking three per day, these either allowed snacking or were focused entirely on weight loss.

What Does the Science Say?

The vast majority of studies only replace one or two meals per day with shakes. These are very useful as this is the recommended method. However, in this instance, we are looking for studies where all of your calories come from meal replacement shakes, and there is a 2018 study that fits the bill.

A study in the British Medical Journal (BMJ) looked at the effect of total dietary replacement on obese men and women in Oxfordshire, England [1]. The aim was to see whether total dietary replacement was more effective for weight loss than a more traditional approach.

The traditional approach involves “a series of appointments with a practice nurse for behavioural weight management advice”. In other words, a nurse would talk to the participants, giving them helpful tips and advice on how to lose weight.

The total dietary replacement group were given 810 calories per day in the form of meal replacement shakes for a total of 8 weeks, followed by 4 weeks where food was slowly added back into the diet.

After 12 weeks, both groups had lost significant amounts of weight. What’s really interesting, though, is that after 12 months, there was a significant difference in how much weight had been lost. The total dietary replacement group had lost over 3x as much (10.7 kg vs 3.1 kg).

This is very important because any diet can lead to weight loss in the short term. It is in the long term (12 months or more) that real results are seen. The weight has not gone back up again, as is the case for so many diets.

Bottom Line: Following a total dietary replacement for a period of 8 weeks, with food slowly introduced in the four weeks after, can lead to significant weight loss over the course of a year.

Why We Do Not Recommend Following a Total Dietary Replacement

While it is very interesting to see such positive results from a study where all meals were replaced by meal replacement shakes, that does not mean that we recommend you follow this course of action.

It is important to note that all participants had easy access to medical experts, and they were clinically obese. This means that more extreme measures could be taken. If you are obese, then you are at a very high risk of heart disease, diabetes, strokes, and many other health issues. This means that the risk/reward ratio changes.

If you are looking to lose a couple of kilograms because you have a holiday coming up, then that risk/reward ratio would look very different. The risks of the diet would outweigh the rewards of losing weight.

That being said, the study actually found that moderate or severe adverse events were lower (11.2%) in the total diet replacement group than in the usual care group (12.3%). So, it is important to note that there are risks with all dietary approaches.

There are also practical considerations. While we believe that Rootana is excellently priced, trying to get 2000 calories from your shakes would end up being quite costly as it would require 5 shakes a day for a man to maintain weight.

This type of diet can also be quite dull, even with a delicious shake like Rootana. It doesn’t allow for any variety, and there is no solid food in your diet whatsoever. If you are clinically obese and your doctor is worried about your health, then that is a small sacrifice to make. But if you are not obese or in danger of dying, then that sacrifice seems unnecessary.

How Many Shakes Should I Have Each Day for Weight Loss?

There are several studies that have looked into this exact question. As you already know, three shakes per day can provide you with excellent results if you follow this diet for 8 weeks. But this is extreme and may not work for people who are not supported by a doctor and research team.

It’s important to get to the root of why people use meal replacement shakes to lose weight. Meal replacement shakes are low in calories compared to a regular meal, with most containing around 400 calories per serving.

The idea is that you use them instead of a 600-1000 calorie meal, and this allows you to create a calorie deficit. Many meal replacement shakes are also high in protein and fibre, both of which are highly satiating, reducing your need for snacking.

Logically, the more meals that you replace with shakes, the greater the calorie deficit you create. However, swapping out too many meals can lead to dissatisfaction, boredom, and the extreme calorie deficit can be a struggle to handle.

That’s why we would recommend swapping no more than two meals per day with meal replacement shakes. That way, you can really focus on providing yourself with a healthy third meal and remain in a decent calorie deficit.

This is born out by the research, with studies repeatedly showing that two meal replacement shakes per day are more effective than traditional dieting techniques [2]. A 2010 study compared a meal replacement shake diet to a food-based diet for 16 weeks.

After 40 weeks, both groups had their measurements taken, and the group on the meal replacement shake diet had lost more weight on average, and there was a higher number of people who had avoided weight regain [3].

You can try three meal replacement shakes per day if you want, but you don’t want to be doing it for longer than 8 weeks. Whereas you can follow a two-shake per-day diet for much longer, possibly indefinitely.

But you can expect decent weight loss results even with just one meal replacement shake per day, provided your remaining meals are healthy and calorie-controlled.

How Many Shakes Should I Have Each Day for Weight Maintenance?

Unless you are quite small already, your calorie requirements will be quite high, so having two or three shakes per day may mean that you struggle to maintain your weight.

In this scenario, having one shake per day would be ideal. You can have a second, allowing you to eat a higher calorie third meal or allowing you to have more snacks.
In this scenario, one or two shakes per day allow you greater flexibility in the rest of your diet. Helping you to maintain a healthy weight while not restricting yourself from the foods you love.

How Many Shakes Should I Have Each Day for Healthy Weight Gain?

This third scenario is quite different from the other two. There are a few meal replacement shakes out there that are very high in calories and can therefore be used to replace meals during a bulk. But most meal replacement shakes are 400 calories or less.

Instead of using the shakes to replace a meal, it is better to use them as high-protein, high-calorie snacks to have alongside your meals.

Can You Live On Meal Replacement Shakes Alone? Final Thoughts

You can live on meal replacement shakes and nothing else but should not plan on doing so for longer than eight weeks. Most people will respond better to having two or even just one shake per day. Finding the right shake for you is also important.

Rootana is a high-protein plant-based complete meal shake that is high in protein, fibre, healthy fats, and low GI carbohydrates. It is ideal for weight loss, weight maintenance, and even healthy weight gain. It just depends on how you use it and what the rest of your diet looks like.

References

[1] https://www.bmj.com/content/362/bmj.k3760

[2] https://academic.oup.com/jn/article/134/8/1894/4688831

[3] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2851659/

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The Nutrition You Need. And Nothing You Don't.

Rootana is a 400 calorie complete meal, with 27 vitamins and minerals. And no unwanted extra ingredients.

Complete Nutrition: Perfect Balance of Macros, Vitamins & Minerals

Rootana is a perfectly balanced combination of complex carbohydrates for slow energy release, the right amount of protein for a balanced meal and all 27 vitamins and minerals.

No Half Measures: 400 Calories Per Serving

Many meal shakes are simply too low in calories and too high in protein to be a complete meal, meaning they're little more than a protein shake. Rootana fuels you effectively and has the perfect macro split for a balanced meal.

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No Sweeteners: No Stevia, No Sucralose, No Aspartame, No Acesulfame K, No Monk Fruit

We don't include any sweeteners as they don't provide any nutritional benefit and may have short or long-term unwanted effects. Rootana is naturally flavored with a small amount of coconut sugar.

Tastes Like Real Food: Because It Is Real Food

With no sweeteners like acesulfame k, aspartame, stevia or sucralose (Splenda), Rootana tastes like real food. That means no artificial after taste and none of that bloated feeling that many sweeteners cause.