I’ve got a client who came to see me for weight loss. BMI is currently 30. He had a brain tumor removed in 2008, and pituitary was damaged and also removed, and he’s now on the following medications: Testosterone every week, hydrocortisone, levothyroxine, and desmopressin. His diet is low in protein, low in omega 3s, but calories don’t appear excessive. My question is, what would be your approach to this? What are your initial considerations? What testing would you do, and what supplements if any would you suggest to consider? It’s just helpful to see if my train of thinking is on the right track.

Chris Kresser: A couple of issues here. One is weight loss. Another is cancer recurrence, prevention of cancer recurrence, and another is hormonal issues given the pituitary damage. There’s a lot going on. As you might expect, I would say the full functional medicine work would be very helpful here. Weight loss is often multifactorial. Cancer certainly is, and the pituitary issue is structural now that it was damaged and removed, so he’s obviously always going to have issues with hormone production. I think in this case ketosis or cyclical ketosis, as well as both a weight loss strategy and reducing the risk of cancer recurrence is really interesting to contemplate. I’ll be writing and speaking more about ketosis both from low-carb ketogenic diet and also cyclical therapeutic fasting as a way of getting into ketosis and also generating some other benefits that ketosis on its own may not have that you get from fasting. We’ll be talking a lot more about those two things as therapeutic strategies in the coming months, but I think they can be very powerful tools for a metabolic reset. As you may have heard, there is some new research suggesting that cancer is at least for some people and in some situations a metabolic disease. If you reduce the availability of glucose in the diet, then cancer cells are not able to utilize ketones whereas healthy human cells are, so you can basically starve the cancer cells and reduce the risk of cancer recurrence and, in some cases, even address cancer when it exists. It’s a somewhat controversial area, and I think there are some claims being made that are a little bit exaggerated, but there is a lot of research that supports this new metabolic theory of cancer, going all the way back to Warburg and his discovery of how cellular respiration happens differently in cancer cells than in human cells and then how we can leverage that understanding to create these dietary approaches that will prevent and in some cases possibly even reverse cancer. That’s an exciting area to look at, and I’m also curious just about fasting and ketosis in a cyclical periodic way as a means of extending lifespan and improving overall health. That might look like every month doing a one- to three-day fast followed by a week of ketosis and then eating a more normal diet for the rest of the time. It’s something that I’ve been experimenting with myself and having some really good results with and also with my patients. We’ll be talking more about that in the months to come.