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Many people often confuse meal replacements with protein shakes and vice-versa. While they may share similar ingredients, nutrients, and flavors, they are designed to achieve very different health goals.
Meal replacements are commonly used for weight loss, while protein shakes are used to build muscle, recover faster, and improve strength and athletic performance.1,2
Deciding which is right for you will depend on several factors, including your current health status, goals, and overall lifestyle. As your goals change, one may become more beneficial than the other.
Let’s take a look at how meal replacements differ from protein shakes, their unique benefits, and which one you should choose.
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A meal replacement is a bar, shake, soup, or powder designed to be a nutritional substitute for a full meal. Meal replacements generally provide all the necessary nutrients you’d typically get from food.
Meal replacements are a convenient, nutritious alternative to a typical meal and can help people achieve their weight loss goals.1
To function, your body requires certain nutrients every day. These fall into one of two categories: macronutrients and micronutrients.
Macronutrients are carbohydrates, proteins, fats, and fiber. Micronutrients are vitamins and minerals. A healthy, balanced diet typically supplies all the necessary macronutrients and micronutrients you need.
Meal replacements aim to provide similar amounts of nutrients you’d normally get from whole foods. This is why they are often fortified with essential vitamins and minerals.
The relative amounts of carbohydrates, protein, and fat in meal replacements will vary depending on the particular product. For example, meal replacement products designed specifically for weight loss may have higher levels of protein and fiber to help keep you fuller longer.
In general, they will mimic the macronutrient ratios found in a regular meal. So the nutritional profile of a typical meal replacement shake may look something like this:
This would equal about 330 calories in total. Meal replacements generally contain 200-400 calories per serving.
A meal replacement is a product designed to fully replace a meal nutrition-wise.
The macronutrient and micronutrient content in meal replacements are meant to mimic the nutrient content in one full meal.
Meal replacement products can come in various forms, including:
These are intended to replace at least one of your normal daily meals.
Research shows meal replacements can be an effective strategy for weight loss. A review of 23 studies found that people who replaced at least one meal a day lost more weight than those following a conventional diet.1
So why are meal replacements so effective? There are a few reasons.
First and foremost, they help control your appetite.
It’s common to feel constantly hungry when trying to lose weight since you’re eating fewer calories than your body is used to. This can hinder your weight loss efforts.
Meal replacement products are typically high in fiber, protein, and other nutrients, which can help keep you fuller for longer.
Meal replacements can help you avoid eating high-calorie junk foods by providing you with a convenient and nutritious alternative. It’s often when you’re tired and just got home from work that you reach for that bag of chips instead of taking the time to prepare a healthy meal.
Meal replacements also help you lose weight by making it easier to track and limit how many calories you eat.
Sometimes it’s hard to judge the correct calorie content of certain foods. It’s easy to underestimate how many calories are in a meal, which means you may eat more calories than you intended. With meal replacements, you know exactly how many calories you’re consuming per serving so you’re more likely to achieve a caloric deficit.
Another great benefit of meal replacements is that they save you time.
You don't have to spend time deciding what to eat, preparing and cooking a meal, and then cleaning up any pans or dishes afterward. You also don’t have to make as many trips to the grocery store since you don’t need as much food either.
We tend to eat many of the same foods day in and day out. If you’re not eating a wide variety of foods or a lot of processed foods, you’re putting yourself at risk for nutrient deficiencies.
In fact, many people are not consuming adequate levels of certain key nutrients. In the US, for example, nearly 70% of adults are not getting the recommended daily amount of magnesium. Magnesium is important for heart and bone health, muscle function, and energy production.3
Meal replacement products contain high levels of essential nutrients like magnesium and vitamin D to help you meet your nutritional requirements.
Meal replacements have the following overarching benefits:
A protein shake is a drink made by mixing protein powder and water, milk, or other liquid of your choice. People may also add berries, nut butters, or yogurt to protein shakes to improve the taste or provide more nutrition.
Like the name implies, protein shakes are mostly protein, usually around 20-30 g per serving. However, they may also contain small amounts of carbohydrates and fats.
The vitamin and mineral content of a protein shake varies depending on the source of the protein. For example, milk proteins are high in calcium and potassium, while certain plant-based proteins contain high levels of iron.4,5
A protein shake is a drink made up of 20-30 g of protein (on average) in powder form mixed with water or milk. People usually add other things like berries or nuts to give the shakes some variety and added flavor.
Protein shakes aren't meant to fully replace meals.
The protein in protein shakes is usually made from plants, milk (casein or whey), egg whites, or beef.
The most common plant proteins are soybean, pea, rice, and hemp. Other less common plant-based proteins include lentils, nuts, and seeds.
These sources are popular because they are complete proteins. This means they contain all the essential amino acids (the building blocks of proteins) your body needs. Many plant sources are incomplete proteins, whereas all animal proteins are complete proteins.
Milk proteins include whey and casein. Whey is a fast-digesting protein that is popular with athletes, weightlifters, and bodybuilders.
Casein protein is a slow-digesting protein that is typically taken at night because it promotes muscle growth during sleep.6
Protein shakes made with egg proteins often only include the egg whites, not the yolk, since most of the protein is found in the whites.
These protein powders are made using meat that has been processed to remove all the fat and carbohydrates and then dehydrated to create a powdered form.
Types of protein shakes:
When you work out, you create tiny tears in your muscles. Your body requires protein to repair these tears, which makes the muscle bigger and stronger.
Protein shakes help supply the body with adequate protein to facilitate muscle repair and growth and enhance recovery.2
By improving recovery, protein shakes can help improve athletic performance.
A review of 32 studies found that supplementing with protein improved both anaerobic (strength) and aerobic (cardio) performance.7
Protein is great at helping you feel full. In one study where overweight women were given whey protein shakes before a meal, they reported feeling fuller.8
Protein helps control hunger by increasing certain compounds in the gut that reduce your appetite.8
Some overarching benefits of protein shakes are:
So which should you choose, meal replacements or protein shakes? It depends on your health and fitness goals, schedule, and diet.
One thing to remember is that meal replacement products will usually be more expensive than protein powders. This is because they include more ingredients and provide more comprehensive nutrition.
If you want to lose weight, opt for a meal replacement shake.
Meal replacements are also an easy, ready-made option for those with busy schedules. If you don’t have the time to prepare breakfast in the morning, you can grab a meal replacement shake or bar and still get a nutritious meal.
If you’re the type of person who hates cooking, meal replacements are a healthy and convenient alternative to preparing a full meal.
On the other hand, if you’re just looking to put on some muscle and get stronger and faster, then a protein shake may be the best choice.
Meal replacements are better for weight loss, while protein shakes are great for bulking up and getting stronger.
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