If you’re living with kidney disease, it’s important to maintain a healthy weight. It’s common for people with chronic kidney disease (CKD) to be either overweight or underweight. If you have gained weight, your doctor may suggest weight loss. However, in certain situations, kidney disease can unintentionally lead to weight loss. IgA nephropathy (IgAN) and complement 3 glomerulopathy (C3G) can also cause you to gain weight from fluid retention and lose fat in certain areas of the body due to kidney-related issues. You’ll need to monitor these changes with your health care team.

Continue reading to learn more about how kidney disease is related to body weight.

Kidney Disease Is Associated With Obesity

Your doctor may calculate your body mass index (BMI) using your height and weight to indicate how much fat is on your body. A healthy BMI is considered to be between 18.5 and 24.9. A BMI of 25 to 29.9 is defined as being overweight, and a BMI of 30 or higher is defined as obese.

Obesity may increase the risk of developing CKD as well as its progression to advanced stages. As many as 1 in 3 cases of kidney disease in the United States are associated with obesity.

Additionally, obesity is associated with the development of several risk factors for kidney disease, such as:

• Type 2 diabetes
• Hypertension (high blood pressure)
• Hyperlipidemia (high cholesterol)
• Coronary heart disease
• Sleep disorders

Diabetes and high blood pressure are the main causes of kidney disease. These two conditions are responsible for up to two-thirds of all cases of CKD. Some research shows weight gain may account for up to 75 percent of the risk of high blood pressure. If you have a BMI of 30 or higher, you are more likely to develop diabetes.

In addition to increasing your risk of developing kidney disease, people with higher body weights and CKD may progress to kidney failure more quickly than people who are a healthy weight. In those with a rare type of kidney disease called immunoglobulin A nephropathy, complications such as high blood pressure, proteinuria (protein in the urine), and kidney lesions were more common in those with higher body weights.

If You’re Overweight, Intentional Weight Loss May Reduce Your Risk of Serious Health Complications

Your doctor may recommend you lose weight to lower your risk of serious health problems.

A 2021 study found that people who lost an average of 13 percent of their body weight had a lower risk of developing type 2 diabetes, sleep apnea (when your breathing starts and stops when you’re sleeping), high blood pressure, high cholesterol, and asthma. In this study, researchers discovered that losing weight reduces the risk of developing CKD.

A 2020 study found that if you attempt to lose just five pounds at several different times throughout your mid-life, you may reduce your risk of death. Researchers in this study found this was true for people even if they had a higher body weight or gained weight over time.

While weight loss can reduce the risk of many health problems, it’s uncertain whether losing weight will help improve outcomes or kidney function for people with CKD. A 2021 review combined the results of 17 different studies involving people with CKD who were overweight and trying to lose weight. Researchers found little or no differences in weight loss, proteinuria, or blood pressure between people trying to lose weight and those who weren’t. More studies are needed to find out if weight loss in people with CKD may help them live longer or prevent heart disease.

If your doctor feels you have a higher body weight and if you are interested in losing weight, talk to them about the potential health benefits. Your doctor can help you find a safe and effective weight loss plan that’s best for you.

Dietary Restrictions for Kidney Disease Can Make Losing Weight More Difficult

If you’re living with kidney disease, you may have to follow a special diet to help balance the levels of electrolytes, minerals, and fluid in your body.

Your diet may limit some of the lower-calorie food options that will keep you feeling full while trying to lose weight.

Examples of foods that may need to be limited if you have kidney disease include:

• High-sodium foods — Added table salt, packaged foods, and fast food
• Protein — Meat, beans, and nuts
• High-phosphorus foods — Deli meat, dairy products, oatmeal, beans, and soft drinks
• High-potassium foods — Oranges, bananas, potatoes, dairy products, and whole wheat bread

A high-protein diet has been proposed as a way to increase weight loss while still feeling full. However, if you’re following a low-protein diet to treat kidney disease, you may not be able to eat high-protein foods.

If you’re following a low-phosphorus or low-potassium diet, talk to your doctor and dietitian about which kidney-friendly foods you can add to your grocery list. Some examples of low-potassium vegetables include iceberg lettuce, cabbage, cucumbers, onions, and bell peppers. Low-potassium fruits include apples, berries, and pears.

Unintentional Weight Loss May Be a Symptom of Kidney Disease

Although higher body weight is related to kidney disease, it’s also true that kidney disease can cause some people to lose weight. As cited in Current Opinion in Nephrology and Hypertension, you may have an increased risk of dying if you lose weight or body fat when you have kidney disease.

Kidney disease can cause you to lose weight if you don’t eat enough calories. As mentioned, a BMI of less than 18.5 is considered underweight.

If you have kidney failure, you may experience symptoms like nausea, vomiting, and loss of appetite that make it hard for you to eat enough food. If you’re on dialysis, your body may need more calories than you’re used to. Additionally, if you have a restricted diet, you may have to avoid some foods you enjoy eating. If you don’t get enough calories every day, you may start to gradually lose weight.

Some people with kidney failure can also develop wasting syndrome (called cachexia), which can cause the loss of fat and muscle. Wasting syndrome is caused by more than just a loss of appetite. In people with end-stage renal disease (ESRD), wasting syndrome can be caused by inflammation and differences in metabolism. Additionally, some appetite-suppressing hormones may build up in your body if your kidneys can’t effectively filter them out of your blood.

One of the unusual things that can happen in people living with the kidney disease called complement 3 glomerulopathy (C3G) is that some parts of the body might become unusually thin. This thinness can be in specific areas, like the muscles or fat tissue in certain parts of the body. Complement 3 is one of several proteins that team up in the body’s defense system, known as the complement system, to fight off infections. In C3G, the complement system can sometimes destroy fat cells under the skin, but it does this unevenly throughout the body. This process leads to some parts of the body appearing abnormally thin and others abnormally large.

If you notice that you’re losing weight without trying, talk to your doctor right away. Your doctor or dietitian may be able to help you find ways to increase your daily calories.

Maintaining a Healthy Weight

Your risk of serious complications and death with kidney disease is increased if you are underweight or at a higher body weight. Talk to your doctor about how to get to a healthy weight for your body and reduce potential health risks and complications of kidney disease.

Exercise may help you lose weight and preserve muscle mass. Check with your doctor about the best type of exercise for you and whether you are healthy enough for physical activity.

Talk With Others Who Understand

On MyKidneyDiseaseCenter, the site for people with kidney disease and their loved ones, people come together to gain a new understanding of different types of kidney disease and share their stories with others who understand life with kidney disease.

How do you maintain a healthy weight while living with kidney disease? Share your experience in the comments below.