A healthy body weight not only protects your cardiovascular system and your joints but it also keeps your metabolism healthy. Did you know that your weight is also important for the function of your new kidney after transplantation? In this article you will learn why this is the case.
The Influence of Your Weight on Transplantation
Surely you know that a healthy body weight is generally beneficial to your health. Many established studies show that a healthy body weight can help protect you against chronic medical conditions such as high blood pressure or joint disease. In general, being overweight is also a risk factor for faster progression of chronic kidney disease and even kidney failure. During dialysis, you mainly control water retention and the quality of treatment through your weight. However, it also plays a decisive role for a successful transplantation, as well as the function of your new kidney. We will now explain why this is the case and in what range your weight should be.
What is BMI?
Before we discuss the exact impact of your weight on your new kidney, let's first take a look at the unit in which your weight is often expressed. This unit is called the Body Mass Index (=BMI). Your BMI puts your body weight in relation to your body size and your body surface. Unlike when you step on a scale and measure just your body weight, the BMI measurement also takes your height into account. Your BMI is calculated quite easily using the following formula:
Body Mass Index (BMI) = body weight (kg) / body size (m)²
What should your BMI be?
The BMI is divided into different categories to more accurately classify your weight. The categories range from underweight to normal weight to overweight. If you are morbidly overweight, this is called obesity. The exact categories are shown in the following table:
What is the impact of your weight before transplantation?
During dialysis, the focus - in addition to reaching your target weight after treatment (also called “dry weight”) - is primarily on reducing weight fluctuations between treatments (called interdialytic weight gain, or IDWG). This protects against water retention and overhydration.
A healthy body weight also appears to be of great benefit in relation to kidney transplantation. This is true both in terms of transplant preparation and for the long-term survival of your precious organ. This has also been suggested by some studies that have examined the relationship between body weight and kidney transplantation. The results of these studies show that people who are overweight and have a new kidney still have a significantly increased risk of cardiovascular disease after transplant. As such, a healthy weight will help you best prepare for surgery and keep your cardiovascular system fit. At the same time, a healthy weight can help maximize the lifespan of your new kidney.
For this reason, many transplant centers have severely restricted access to the waiting list for individuals with a BMI of 35 to 40 kg/m² or more. This means that overweight people are much less likely to be transplanted. The risk that the new kidney will not last as long because of the excess weight is too great. Even the current medical guidelines recommend lowering the BMI of recipients to 30 kg/m² prior to transplantation to improve the outcome of transplantation. Despite being on dialysis, you should try and aim to go into a kidney transplant as fit and strong as possible in order to be able to influence the risk of success!
Are you slightly over your target body weight and possibly about to undergo a transplant? If this is the case, your dialysis team and transplant center can offer support on this topic. If you have not already been informed about this topic, ask for support in optimizing your weight.
What impact will your weight have on the function of your new kidney?
As just described, obesity can accelerate the progression of chronic renal failure to ultimately lead to kidney failure. So it stands to reason that being overweight after transplantation can also be dangerous for your new kidney. Some studies show that obese people are more likely to experience delayed function of the new kidney after transplantation. The new kidney also did not appear to function optimally in the long term in this group of transplant recipients. A delayed functional uptake of the new kidney was also observed in almost half of the transplanted individuals that had a BMI of more than 35 kg/m².
At the same time, as you already know, obesity poses a risk to the health of your cardiovascular system. Your cardiovascular system is usually already somewhat damaged due to chronic kidney failure and possible comorbidities such as high blood pressure or diabetes. It is therefore all the more relevant that you become active if you feel that any of these points apply to you!
As you see, a healthy weight is immensely important before as well as after the transplantation. As discussed above, by being able to appropriately control your weight, you can have a significant influence on the chances of success and survival for your valuable transplant, both in the short and long term.
Weight fluctuations after transplant
As you already know, weight fluctuations on dialysis are not the exception, but rather the rule. Although your overall weight is the most important thing after transplantation, fluctuations in your weight and weight gain are not uncommon. There are a variety of reasons for this, two of which are especially important.
- Kidney Function: If there is a decrease in the function of your new kidney after transplantation, you may experience water retention, which can lead to weight gain. In order to detect this as early as possible, your weight will be regularly monitored and documented by your medical team. At the same time, the function of your new kidney will be monitored by laboratory values. You can learn more about this topic in other parts and resources of the Mizu app. In your logbook, you can also regularly document your BMI and weight values.
- Immunosuppressants: This type of medication suppresses the function of your immune system to protect your new kidney from being rejected by your body. At the same time, these medications can also cause weight gain and high blood sugar levels. You can learn more about the side effects of these drugs and how you can best manage them from your treating medical team and in the other articles of the Mizu App.
What can you do if you are overweight?
To control being overweight before and after transplantation, your behavior, above all, plays an important role. Both before and after transplantation, sufficient exercise and a healthy diet are required. This is especially important with regard to taking your new medications (e.g. immunosuppressants). Low-intensity physical activities such as walking, cycling or hiking are particularly suitable after transplantation.
If you are having trouble managing your weight, professional dietary counseling from someone that has knowledge of kidney disease, can help both before and after transplantation. In some cases, working with a motivated and supportive team in a rehabilitation setting to get your weight under control may be possible before your transplant.
As you can see, there are many ways to give your new kidney the best possible start in its new workplace by maintaining a healthy weight. The key to achieving this lies largely in your own hands.
