Dr. Jason Fung is one of the leading experts in weight loss in the world now; people are coming to him like a shrine.

What does nephrology have to do with weight loss?

That’s an interesting question. The biggest cause of kidney disease is type 2 diabetes. And so over the past 20 years, we have been seeing more and more kidney disease. Obesity has gone up and so has type 2 diabetes, and that has sort of translated into a lot of kidney disease. I see people at the end when they have all this disease that is brought on by their type 2 diabetes. For many years I just practiced as a normal nephrologist. I would put them on dialysis, I would give them pills, and so on. It gradually dawned on me that the entire process was incorrect. Let’s look at the chain of causality here. You have ‘being overweight’ which leads to type 2 diabetes, which leads to kidney disease.
Well, how do you get people better from kidney disease? Obviously, you have to get rid of type 2 diabetes, and in order to get rid of type 2 diabetes, you’ve got to get rid of the weight. But every doctor who has been trained to treat you at the end of that chain, where the kidney disease is already there. “Oh, what drugs do you need? What surgery do you need? What dialysis do you need? What lines do you need to put in? What procedures do we have to do for you?” It is like you will never get better doing that.
What you need to do is go up the chain and go to the root cause, which is the weight. If you lose weight, then you don’t get the diabetes, and therefore you don’t get diabetic kidney disease. That is the only way to treat people.

That is why a few years ago I became very interested in the question of how to lose weight because it impacted me directly. This has been a change in everything; in terms of how I treat patients. If I see them early enough, if they don’t have kidney disease, I am going to focus very heavily to get them to lose weight, to improve their metabolic health, and then prevent type 2 diabetes, which will prevent me from needing to treat them at all.

Can kidney disease be reversed with your diet? Can losing weight reverse kidney disease?
Only in the very early stages. Remember that the kidney disease comes at the very end of the chain. Usually, it is 20 years of type 2 diabetes, and 30 years of obesity and the damage that is done cannot be easily reversed. If you don’t change the oil in your car and it gets damaged and then you say “I think I am going to change the oil in my car”. That is great, but it may or may not make it better. Kidney disease, once it becomes established, is actually very hard to reverse. It needs to be prevented, and that is the bottom line. I sometimes hope it would reverse and sometimes we do see it, but it is not common. But, at least, we hope to slow down its progression by getting people to lose weight and reverse their type 2 diabetes.