Meal replacement shakes are popular because they are an effective way to lose weight. But anyone who’s thinking about trying them is bound to have come across some warnings about how these shakes can be bad for your kidneys. Well, is there any truth to this?
Meal replacement shakes aren’t inherently bad for your kidneys. Scientific studies have proved these shakes to be perfectly safe, but there can still be risks associated with drinking meal replacement shakes that are high in protein. You need to keep the amount of protein in check.
In this article, we will be exploring this subject in detail. And although meal replacement drinks don’t inherently lead to kidney problems, if your diet already puts you at risk of getting kidney stones, these drinks can help accelerate the process. We will also be looking at how you can self-assess your risk of kidney stones.
Meal Replacement Shakes and Kidney Stones
Let’s jump right into the main concern. A lot of people who are new to meal replacement shakes are often concerned about the effects these shakes have on our kidneys.
There is a popular belief that meal replacement shakes can lead to kidney stones. This is, however, not completely true.
Most meal replacement shakes are high on protein. And yes, the protein in these shakes does indeed do two different things that can lead to kidney stone formation.
Firstly, the protein in meal replacement shakes results in the production of oxalate. Oxalates are some of the most common metabolic products that the human body produces when digesting protein.
Naturally, if you’re drinking a meal replacement shake high on protein, the body will produce a lot more of these oxalates that are released via urine.
The second thing that the protein in these shakes does is that it increases the amount of calcium production in the body.
Since protein requires an acidic environment for digestion, when the body facilitates this, it also releases a lot of calcium to control the acidic environment. And this calcium is, in turn, released via urine.
Both oxalates and calcium can lead to the formation of kidney stones over time. But you should know that unless you’re consuming an excessive amount of these protein-rich shakes, this is highly unlikely.
As mentioned above, both the formation of oxalates and calcium are neutral mechanisms, meaning that under normal circumstances, both are released via urine.
So, the bottom line is that meal replacement shakes do not lead to the formation of kidney stones as long as they do not have an excessive amount of protein in them, or you don’t take extra protein supplements alongside them.
Moderation is the key. If taken in moderation, meal replacement shakes are perfectly healthy.
The Good News: Science Says It’s Safe!
Meal replacement shakes are incredibly helpful for anyone who is looking to lose weight. But there’s a popular rumor that they can lead to problems in your kidney, liver, or bone density.
While we have just debunked the rumor regarding kidney stones in the previous section, we will present the results of scientific research (Protein-enriched meal replacements do not adversely affect liver, kidney or bone density: an outpatient randomized controlled trial) that proved that protein-enriched meal replacement shakes do not adversely affect your kidney or even your liver or bone density.
The results of this 2010 research were published in the Nutrition Journal. The test was a placebo-controlled clinical trial, meaning that the patients had no idea what they were being given.
The patients were divided into two groups. One was given an isocaloric meal plan that used high protein-enriched (HP) meal replacement, while the other was given standard protein (SP) meal replacement.
The subjects were 100 obese men and women (MBI between 27 – 40 kg/m2), all over the age of 30. The HP group was given 2.2 grams of protein/kg of lean body mass per day, while the SP group was given 1.1 grams of protein/kg of lean body mass.
For the first three months, the meal-replacement was given twice every day. And for the nine months after that, it was given once a day.
The researchers measured five factors (body weight, kidney function, liver function, lipid profiles, and bone density) at baseline (the beginning) and the end of 12 months for both groups (HP and SP).
The results showed no significant difference in weight loss, liver functions, kidney functions (serum creatinine, urea nitrogen, 24-hour urine creatinine clearance, and calcium excretion), or bone density.
This was definite proof that protein-rich meal replacement shakes do not affect the kidney to the extent that many people may believe they do.
Picking the Right Meal Replacement Shakes
While we have established that meal replacement shakes are not as harmful to the kidney as you may have led to believe, there are still concerns regarding the right kind and right amount of these things.
As we have discussed multiple times above, the main culprit in meal replacement shakes is the excessive protein. With solid sources of protein like milk, cheese, meat, etc., the body takes its time to digest the protein. However, this is not the case with meal replacement shakes. The protein in these powders is absorbed much faster by the body.
For this reason, you should always be mindful of the amount of protein you’re putting in your body while replacing your regular solid meal for a meal replacement shake.
You will have to track the amount of your daily protein intake and make sure it is within a healthy range. The recommended amount depends on how much physical activity you partake in.
- If you’re an athlete or someone who does strength training regularly, you will need 0.7 to 0.8 grams of protein for every half a kilo of your body weight.
- If you are someone who engages in a minimal amount of physical activity, your recommended daily dosage is 0.3 grams per half a kilo of your body weight.
Measuring the amount of protein is pretty straight forward. Check the labels of your meal replacement powder for the amount of protein per given weight.
Now depending on how many times per day you plan on drinking these replacement shakes, divide the amount accordingly.
If your brand of meal replacement powder has too much protein in it, you can opt for an alternative brand that comes with a lower amount of protein.
You can then add nuts or cottage cheese to your shake to make up for the protein deficit (since these contain slow-digesting protein).
Do Meal Replacement Shakes Help You Lose Weight?
The reason most people choose to consume meal replacement shakes is that they want to lose weight effectively. And these drinks really can help people lose weight.
It is particularly effective for people who have been cursed with bad genetics that makes it harder for them to lose weight. Meal replacement shakes are designed to make you feel full. And it does so by putting in no more than 200-250 calories into your body.
If you compare this to the average snack or a meal, you would otherwise consume to fill the craving, you will start to notice how effective these drinks really can be.
A lot of people, however, seem to confuse these drinks with protein shakes. In the next section, we will help you differentiate between the two.
Protein Shakes vs. Meal Replacement Shakes
At this point, it is worth clarifying that there is a distinctive difference between protein shakes and meal replacement shakes.
Simply put, meal replacement shakes are meant to substitute regular meals, with a lot less calorie intake. They can be of great help in losing weight. These shakes contain a healthy amount of protein, whose primary function is to manage your appetite and make you feel full.
Protein shakes are a bit different. Their primary purpose is to add more protein to your body. They are not a substitute for regular meals, and often people who drink protein shakes do so in addition to consuming a healthy amount of solid food.
We have attempted to illustrate the difference between these two shakes in the table below:
|Protein Shakes||Meal Replacement Shakes|
|They are usually consumed as a supplement either before or after a workout (usually involving strength training).||They are usually consumed once or twice per day as a lower-calorie substitute for regular meals.|
|These shakes can contain up to 25 grams per drink. They do not contain vitamins and minerals.||These shakes contain a relatively lower amount of protein. They contain enough vitamins and minerals.|
|The primary purpose of these drinks is to repair and build muscle.||The primary purpose of these drinks is to help one lose or maintain weight in a healthy way.|
So what constitutes a good meal replacement shake? The European Union Commission Regulation can be held at good authority in this regard. According to them, a proper brand of meal replacement shake has to meet the following criteria:
- Must provide 200 – 250 calories of energy per drink
- Total energy content must consist of 25-50% protein
- Total energy content must consist of less than 30% fat
- Must contain more than 30% of the nutrient reference values of Vitamins and minerals
What Exactly Are Kidney Stones?
We’ve mentioned kidney stones quite a few times already in this article. So let us look at what exactly they are. However, to understand what a kidney stone is, one must be familiar with the functions of the kidney.
Our kidneys are vital filtering systems that help our bodies get rid of all the metabolic by-products and the toxins. These toxins and by-products are usually removed via urine.
But sometimes they will interact with the mineral salts circulating in the kidneys to form solid compounds that don’t dissolve. These are referred to as kidney stones.
Many types of kidney stones are formed in this way. But two types, calcium stones and uric acid stones, comprise almost 90% of all kidney stones diagnosed in patients. Let us look briefly at each of these two types:
Calcium stones are by far the most common type of kidney stones diagnosed in patients, accounting for up to 80% of all cases.
They form when oxalate, a type by-product of metabolism, or phosphate, a common additive and preservative used in foods, interacts with calcium in the urine.
The binding of oxalate and calcium results in calcium oxalate stones, whereas the binding of calcium and phosphate results in the formation of calcium phosphate stones.
Calcium oxalate stones are usually formed in acidic urine and are the more common of the two kinds. Calcium phosphate stones are formed in alkaline urine and are not as common.
Uric Acid Stones
Uric acid stones are the second most common type of kidney stones diagnosed in patients, accounting for about 10% of all cases.
They are common in patients who have a high level of uric acid. When uric acid level in the urine exceeds a certain amount, the urine becomes extremely acidic. This acidic environment results in the formation of uric acid stones.
If left untreated, kidney stones can lead to serious problems and even complete kidney failure. The symptoms include a characteristic pain in the lower side of your back.
Knowing if You’re at Risk of Kidney Stones
Knowing if you’re at risk of kidney stones can help you access your use of meal replacement shakes. If you are at low risk, most meal replacement shakes are completely safe for you to drink.
However, if you are already at a high risk of kidney stones, you may want to be careful of the amount of protein your meal replacement shake has.
Four factors put you at high risk of kidney stones.
A common cause of kidney stones is the lack of water in the body. This comes down to the working mechanism of the kidney.
Your kidney is a filtering system that rids the blood of toxins and unnecessary compounds that are created as metabolic by-products. To remove these toxins from the body in the form of urine, the kidney requires plenty of water.
If you’re chronically dehydrated, the amount of uric acid in the kidney rises exponentially. This highly acidic environment thus facilitates the formation of kidney stones like calcium stones and uric acid stones.
If you’re drinking plenty of water, you are at a lower risk of kidney stones.
High Amount of Sodium Intake
Another very common reason for getting kidney stones is the high amount of sodium intake.
The modern diet is heavy on sodium. Each time you consume something salty, you are putting sodium in your body. And the nature of the modern diet can make it difficult to track just how much sodium we are putting in our bodies. And the result is we consume more than the body needs.
In response to this excess of sodium, the kidney pulls in more calcium as a substitute for it. This eventually leads to an excessive accumulation of calcium in the kidney, which can, in turn, lead to the formation of calcium stones.
Furthermore, if an excess of oxalate or phosphate accompanies this excess of sodium, it can lead to more complications. Hence, the careful monitoring of sodium intake is a necessity to prevent kidney stones.
High Amount of Oxalate Production or Consumption
An acceptable amount of oxalate is always present in the body. They are formed as by-products of metabolism when the body digests protein.
But some foods like berries, nuts, chocolates, sweet potatoes, etc. are naturally high in oxalate. And when you consume an excess of these items, you are putting more oxalate into your body.
Excessive oxalate presence in the kidney can lead to the formation of calcium oxalate stones, as we have already discussed above.
High Amount of Sugar Consumption
Sugar isn’t something most people associate with the formation of kidney stones. And rightfully so, since it cannot directly cause kidney stones. But there are still some forms of sugar that can indirectly lead to the formation of stones.
Sucrose and fructose are two examples. The former requires an excess of calcium for digestion, while the latter can trigger the production of excess purines.
The excess calcium can lead to the formation of calcium stones, whereas the purines break down to form uric acid, which can lead to the formation of uric acid stones.
Like with sodium, it is necessary to monitor the amount of sugar you put in your body.
Meal replacement shakes aren’t bad for your kidney. There have been studies that have debunked the link between these drinks and kidney problems.
However, it is necessary that you keep the amount of protein you put in your body in check.
There are also a few other things like sodium and sugar that you need to regulate to avoid kidney stones.
If you keep all these things in check, meal replacement drinks can help you in losing or maintaining your weight. We hope this article helped you.