Meal replacement vs protein shakes are often confused with one another.

As the name suggests, meal replacement shakes are intended to replace a full meal (breakfast, lunch or dinner).

Protein shakes are designed to supplement our diet, not to replace a meal. They are more commonly used as an easy way to increase our overall protein intake.

Meal replacements and protein supplements are not for everyone and, in some instances, should be used cautiously.

In most situations, a healthy diet focussed on whole foods should be the focus. However, let’s discuss when we might use meal replacements and protein supplements…

Meal Replacement Drinks

Who Uses Meal Replacement Drinks?

Most commonly, meal replacement shakes are used as a low-calorie, convenient option for people looking to lose weight, with the aim of obtaining essential nutrients that we would usually get from whole foods (we will touch more on this later).

However, they can also be used in many other situations:

• For athletes in need of a quick recovery drink or an easily digestible fuel source containing a balance of macronutrients (note: athletes should rarely be using meal replacement powders or shakes as a replacement; they should be treating it as a supplement due to their high energy requirements).
• For elderly people who struggle to prepare their own meals or need additional nutrients in an easy-to-ingest format.
• For patients who may struggle to eat solid foods after surgery or due to illness to help them meet their nutritional needs.
• For people looking to gain weight – meal replacements aren’t just for weight loss, they can be used in all aspects of weight management, including weight gain (by using meal replacement shakes between meals, it can be easier to achieve a calorie surplus).

Protein Drinks

Who Uses Protein Drinks?

Protein shakes are most commonly used to help people achieve their fitness goals, whether that be to increase muscle mass or to assist with post-workout recovery. Protein shakes come in a variety of forms – whey protein shakes, casein protein, hemp protein, pea protein – you name it! I have covered protein in a few blogs, check out this one on hemp protein vs whey protein or this one on whey protein vs BCAAs to boost your protein knowledge and help you make an informed choice!

Protein shakes do have a place outside of muscle growth and recovery, they are also useful for:

• Weight management – protein is known as the most satiating macronutrient which, in simple terms, means it helps keep us fuller for longer. This can help people feel more satisfied when they are they are on a weight loss plan or it can be used as part of a healthy, balanced diet to assist with appetite control.
• Elderly nutrition – as we age, our protein requirements increase. Our muscle mass, strength and function decrease with age (1) so it becomes super important to increase protein intake to help slow this process. Proposed protein requirements for elderly people are at least 1g per kg of body weight (2) – protein shakes can assist in meeting this target.
• Vegans and vegetarians – generally these diets are lower in protein, though, in the past few years it’s been great to see more and more high-protein vegan/veggie recipes and meal inspiration. Still, compared to a diet containing animal products, they can be on the lower side for protein and thus protein shakes can be used to help meet protein goals.

Benefits of Meal Replacement Shakes

Weight Management 

This is probably the most common reason for meal replacement shakes, there is some evidence to suggest they can be equally as effective as a normal structured weight loss diet.

A systematic review and meta-analysis of 23 studies (3) found that programmes incorporating meal replacements led to greater weight loss after 1 year. This was especially true if the participants had an enhanced level of support (i.e. from a dietician or medical professional).

A study (4) published in the Journal of Nutrition split obese/overweight individuals into 2 groups:

1) A low-fat/calorie diet group

2) A meal replacement group who were provided shakes/bars for 2 meals before eating a low-fat evening meal

Both diets were matched for calorie intake – around 1400kcal.

After 3 months, group 1 lost an average of 6.6kg and the meal replacement group, 6.0kg.

After 6 months, group 1 lost an average of 9.2kg while the meal replacement group averaged 9.0kg.

You can look at this two ways, either meal replacements can match a standard weight loss diet OR meal replacements do not perform better than a standard weight loss diet.

I tend to side with the latter view. The meal replacement group had 2 meals per day removed and replaced with shakes/bars but didn’t lose any more weight than the individuals in group 1 who were eating 3 meals per day. How do you think their overall diet satisfaction was compared to group 1?

I’d hypothesise that it wasn’t great, if the weight loss results were significantly better then maybe it would be worth the hardship. But they weren’t.

Convenience

However, say you are a really busy person and have no time to eat during the day. This may be the perfect weight loss strategy for you – 2 shakes/bars in the daytime and then an evening meal resulting in significant weight loss.

We commonly see busy people eat few calories or even nothing at all in the daytime but then binge eat in the evenings. Meal replacements could be a convenient way and viable strategy to support these types of individuals in their weight loss journey, without sacrificing essential vitamins and minerals.

Health Conditions

Meal replacement shakes can be a really important tool in the recovery phase of a number of health conditions.

For example, in certain eating disorders, such as anorexia, a meal replacement shake can be utilised to provide the necessary nutrients to the patient, supporting recovery and the road back to overall health.

Type 2 diabetes and metabolic syndrome (a condition where an individual has numerous risk factors for cardiovascular disease) are further examples of the effective uses of meal replacement shakes.

A study (5) in 2018 highlighted the effectiveness of meal replacements and lifestyle education on diabetic markers – after 12 weeks the fasting blood sugar levels of 42% of the participants returned to normal levels, and 16% of the individuals no longer met the criteria to be diagnosed with metabolic syndrome.

It’s likely these promising results are due to weight loss and not any stand-alone effect of meal replacements. Nonetheless, meal replacements were a major contributing factor to weight loss – 90% of the participants lost weight by the end of the study.

Benefits of Protein Shakes

Muscle Gain

You’ve probably heard it all before – protein is vital for muscle growth, repair and maintenance as well as preventing muscle loss.

Whey protein is typically the most common form of protein found in protein shakes, it contains all nine essential amino acids which can maximise muscle protein synthesis leading to the growth of and repair of muscle tissue (6).

This is great for gym lovers and athletes alike – ultimately protein shakes can help improve athletic performance by optimising recovery and creating anabolic conditions to stimulate new muscle growth after our gym or sports sessions.

Weight loss

Not just for athletes, protein shakes are great for helping with weight loss and maintaining muscle mass in a calorie deficit.

As mentioned before, it helps keep us fuller for longer which can help with appetite control to help us meet our weight loss goals.

Protein reduces a hunger hormone called Ghrelin. Ghrelin is mostly found in the stomach and, when levels increase, it sends messages to the brain saying “FEED ME!”.

By reducing Ghrelin levels, we have less of an urge to eat, subsequently, we tend to consume fewer calories which helps with weight loss outcomes.

Meal Replacement vs Protein Shakes: Which One Should I Choose?

If your goal is to replace 1-2 of your meals with a convenient and macronutrient-balanced alternative to help meet your goals, then meal replacement is an option.

NOTE: consult with a medical professional before using meal replacements.

If your goal is to increase protein intake, protein shakes could be what you are looking for.

Key Considerations Before Taking Meal Replacements

• What are your nutrition goals? Meal replacements are commonly low in calories (typically between 150-200 calories). While this can be beneficial for weight loss in obese people, it’s important to consider your personal calorie requirements. It’s possible you could be severely restricting yourself which has a whole host of risk factors including – nutrient deficiencies, muscle loss and gallstones. A healthy rate of weight loss is 1-2 pounds per week.
• Do you need meal replacements? Have you tried other dietary approaches, particularly whole food, minimally processed diets? In my opinion, for weight loss in non-clinically obese people, meal replacements should be a last resort. A whole-food first approach with a structured calorie deficit should be the first approach. It is always my opinion that we should be adding to people’s diets not taking away meals.
• Have you done your research? In some countries, meal replacements are not regulated meaning such products do not need to meet a set of standards to qualify as a meal replacement. They can also contain artificial sweeteners or artificial ingredients (not necessarily a bad thing but something to note). Make sure to do your research to meet your individual needs.

Key Considerations Before Taking Protein Shakes

• How many grams of protein do you need? Typically, for resistance-trained individuals, the evidence suggests 1.6g per kg of body weight.
• Are you already getting enough protein?
• Can you get your protein from whole foods rather than dietary supplements?
• Do you have any dietary preferences i.e. plant-based proteins or animal-based proteins? Again check out this blog where we compare hemp vs whey protein.

The Bottom Line

If you have consulted with a medical professional, meal replacements may be a good strategy to help with weight loss (among other things).

There is definitely evidence in the literature to suggest they can be effective but, again, I emphasise that there is nothing like a whole-food first approach to encourage positive eating habits while also having beneficial effects for weight loss and overall health.

I accept though, that this approach isn’t always possible and meal replacements may therefore be the way forward for you. It is important to ensure you are having solid food/proper meals alongside your meal replacements – usually, your evening meal would be an actual meal. Without this, your energy intake would be very low and could lead to complications as mentioned before – deficiencies, muscle loss, gallstones.

Protein shakes are a great way to increase our overall protein intake, they are typically lower in fat and carbohydrates while giving us a big boost of protein. Meanwhile, meal replacements are designed to be a balance of carbohydrates, fat and protein to mimic that of a meal.

Protein shakes are great for an active individual, the elderly and people looking to lose weight by keeping them fuller for longer!