The Keto Diet And Your Kidneys

18 Sep The Keto Diet And Your Kidneys

Have you thought about losing weight over the last few years? If so, then you have undoubtedly considered the keto diet. It consistently ranks among the top 10 diets in the United States and is a popular topic of conversation when my patients come talk to me in my office.

Here’s what they want to know: 

-Can a keto diet help me lose weight and prevent my kidney disease from getting worse?

-Is a keto diet safe for me even though I have kidney disease?

Because my job is to do everything in my power to help people keep their kidneys in the best possible shape, I give them the most straightforward and scientific answers I can. In this article, I’ll share a balanced look at the impact of the keto diet on the kidneys and whether the keto diet is safe for people with kidney disease.

Remember I’m not your doctor…

Now, before we go any further, it’s important to know some things. First, though I am a kidney doctor, I am not your doctor and I do not provide any medical advice. Any changes to your diet should be discussed with your doctor or dietitian. This is a general overview of my interpretation of the data and the science.  

What is the keto diet:

The keto diet is a high fat, low carbohydrate, moderate protein diet that puts your body in a state of ketosis. Once your body is in this state, it burns fat to produce energy, and this causes you to lose weight.

A typical keto diet includes high fat foods like meat, fatty fish and seafood, eggs, high fat sauces from coconut oil, olive oil, heavy cream, and butter, full fat dairy products, and vegetables that are lower carbohydrate such as green beans, broccoli, cabbage, cauliflower, broccoli and others. At the same time, you limit foods that are higher in carbohydrates like rice, bread, pasta, starchy vegetables, many fruits, legumes, and processed foods.

The restrictions for a keto diet are strict. In order to keep your body in a state of ketosis, and one that will lead to weight loss, you can’t stray too far from the recommended nutritional requirements. That can create stressful situations and a lifestyle that may be hard to stick with for the long term.

What Does Science Say?

Researchers are still sifting through the data on the keto diet. From my review, the keto diet can certainly help you lose weight and better control your diabetes in the short term, but the long term effects are unknown. It’s also clear that the diet can be difficult to follow for years at a time. Moreover, the benefits of a keto diet over other restricted ways of eating such as intermittent fasting, plant-based, DASH, Medieterranean, Paleo, etc., are still to be determined. So, yes, keto may help you shed 20 lbs over a few months, but can you keep it off long term, can you stick with the restrictions for months and years at a time, and does the focus on high fat, low carbohydrate food cause long term damage? The jury is still out.

Keto Diet and Your Kidneys

Chronic Kidney Disease (CKD) is a generic diagnosis given to people who have some kind of kidney damage. CKD is divided into 5 stages depending on how well your kidneys are filtering. It can be mild, producing zero signs and symptoms at stage 1, or severe, causing hospitalization and requiring you to have a kidney transplant or go on dialysis at stage 5.

Obesity, diabetes, and high blood pressure risk factors for the development of kidney disease, and each of these risk factors can be managed by diet. So for people with kidney disease or who are at risk for developing kidney disease, maintaining a healthy weight and keeping diabetes under control are two of the most important things that they can do. Because of this, many of my patients often ask me about diets that will help them lose weight, and whether or not they are safe for their kidneys. I get questions about paleo, Atkins, vegan diets, etc. But more often than not, over the last few years, the questions revolve around the keto diet.

Is the Keto Diet Safe for Your Kidneys

Similarities and Safe Aspects

Let’s start with the safe aspects and similarities between a kidney-healthy way of eating and a keto diet. These are the aspects of the keto diet most people can safely follow and, frankly, are the keys to any healthy dietary pattern whether it’s keto or vegan.

• Avoiding ultra processed high carbohydrate foods like chips, pretzels, snack foods, candy bars, etc.

• Avoiding sugary drinks like soda, juice, sweetened tea, sugary coffee drinks, etc.

• Avoiding cookies, cakes.

• Cooking at home

• Limiting portion size

• Eating low carbohydrate vegetables

Differences and Potential Dangers

The differences and dangers that arise when someone with CKD wants to go on a keto diet center mainly around protein, but extend to other areas as well.

Keto Diet Protein Intake
1.2-1.7 grams/kg body weight/day

Chronic Kidney Disease Protein Intake
0.6-0.8 grams/kg body weight/day

In a keto diet, protein intake usually stays between 1.2-1.7 grams of protein intake/kg of body weight each day, with no distinction between animal and plant-based proteins. If you have normal kidney function, without any risk factors for kidney disease, it is unclear whether this amount of protein will harm your kidneys. Anyone who tells you they know the absolute answer to this question is misreading the data or only looking at studies that support their view.

On the other hand, we do know that people with kidney disease benefit from a lower protein intake. Most dietitians and doctors recommend between 0.6-0.8 grams of protein/kg of body weight for people with Stage 3-5 Chronic Kidney Disease. That’s half as much protein as the typical keto diet.

Why Limit Protein in Chronic Kidney Disease

Excess dietary protein has the potential to put extra stress on the kidneys. In the most simplistic explanation, the kidneys have to work extra hard to process protein once you eat above a certain amount. This extra work, also known as hyperfiltration, can cause the tiny filters in the kidneys called glomeruli, to become scarred. If these filters get scarred, then kidney function can decline over time and kidney disease can worsen.

While the keto diet is not a super high protein diet, the added protein load from 1.2-1.7 gm of protein/kg of body weight is still well more than is recommended for people with kidney disease.

For this reason alone, I often tell my patients that I don’t recommend the keto diet as the best weight loss strategy for them. Remember, again, that each individual decision should be made with the input of your doctor and dietitian.

Other Differences and Potential Dangers

• Carbohydrates: In a typical kidney-healthy diet, carbohydrates are often used to provide calories without giving extra protein. In the keto diet, carbohydrates are strictly limited.

• Sodium: A lower sodium diet often benefits people with chronic kidney disease because it assists with the management of high blood pressure and can prevent fluid retention. In the keto diet, extra sodium is often recommended, especially when you are starting out.

• Plant-based proteins: Recent research has suggested that plant-based protein may be better for people with kidney disease than animal protein. In the keto diet, there isn’t a distinction between the two.

Kidney Stones

Most of the research on kidney stones and the ketogenic diet has been in children with epilepsy since this diet was initially designed as a dietary management tool for refractory seizure disorders in kids. Interestingly and surprisingly, I couldn’t find any recent literature that dives into the kidney stone risk for adults who have started a keto diet for weight loss. What we do know is that high animal protein and sodium intake can be a risk factor for certain types of kidney stones and so the keto diet may increase the kidney stone risk in those people.

Verdict:

While the data is still coming in on the long term effects of a keto diet, I believe there are too many risks and unknowns to safely advise this type of diet for most people with kidney disease. This is especially true for people with Stage 3-5 Chronic Kidney Disease, who already have significant dietary restrictions and who may benefit from a diet that is much lower in protein intake. Additionally, it remains to be seen if people can remain on a keto diet for many years, and this is an important part of any healthy, long term dietary pattern.

Future Areas of Interest

As we learn more about the benefits of diet on kidney disease, and the long term effects of a ketogenic diet, there may be areas of overlap and areas worth studying further.

• Would a vegan, higher protein keto diet produce the same risk on the kidneys?

• Do some people with Stage 1 or 2 kidney disease who also struggle with obesity benefit from a keto diet for weight loss without straining the kidneys?

• Does a long term keto diet cause increased or decreased risk of kidney disease development in people who don’t have any other risk factors?

• Does a higher protein vegan diet that doesn’t produce ketosis provide kidney benefit?

If you’re just joining me, be sure you signed up for my newsletter. I have a new book coming out this fall titled The Cooking Doc’s Kidney-Healthy Cooking: A Modern 10-Step Guide For Preventing And Managing Kidney Disease.