So we are all aware of the benefits of fasting, and one of the introductions I had to the therapeutic effects of fasting was listening to Dom D’Agostino talk about Thomas Seyfried on the Tim Ferriss Podcast, and he talked about doing a five day quarterly fast as a way to prevent the cellular damage to help protect the body against cancer. Obviously nothing is guaranteed, but that a man who researches in the field of cancer does this is certainly compelling enough to warrant considering it.
The idea of fasting for days (as opposed to hours, which is what time restricted eating, or TRE is) is daunting to a lot of people – how on earth do you just not eat?!, however it might not be that you have to completely do without food in order to reap the benefits of fasting. Valter Longo’s Longevity diet is a perfect example of this – his regime of low calories, low protein for five days is suggested to confer the same benefits as fasting – indeed human research shows its potential utility as an adjunct therapy to chemotherapy for breast cancer patients, with future studies set up to test its medication lowering effect in type 2 diabetes. There is also interest in a calorie-restricted, fasting mimicking approach for the reduction of cardiovascular disease (though there is much debate surrounding the overall effects of protein on these metabolic markers, which you can read here). In all, the robustness of research around restricting intake may well be more compelling than focusing on increasing certain nutrients or phytochemicals in order to enhance health and lifespan. The overabundance of calories is undoubtedly a contributor to oxidative stress and damage that leads to cellular damage, so times of energy deprivation, then, well below usual daily intake, may well protect us in the long term. Thomas Seyfried, among others, feels that a fasting regime of at least three days may be enough to clear out damaged cells, however for some people that might not be a realistic option for whatever reason.
I was interested, then, to hear Dom D’Agostino on the latest Peter Attia podcast talk about his thoughts on the benefit of a ketogenic diet for people who were otherwise healthy and didn’t have any metabolic markers that place them at risk of disease (i.e. elevated blood sugar or insulin, excess body fat etc) and who may not necessarily have to worry about restricting carbohydrates in their everyday life. He put up a good case for intermittently doing a time restricted eating ketogenic approach for 5-7 days each month as a way to get the same benefits of a 3 day fast (it is considered that 3 days of fasting may be the minimal amount required to see real benefits from a longevity standpoint). Dom makes a case that in normal life this would help enhance metabolic flexibility; whilst we all have the machinery to burn both fat and carbohydrate, the reality is that most of us who are exposed to both a carbohydrate dominant diet and/or the effects of increased stress load would have the enzymes for fat burning suppressed compared to those burning carbohydrates. Intermittently following a ketogenic diet would help us become better at utilizing ketones for an energy source, and helps enhance the genes required to do so, and the more often you are in a state of ketosis, the more benefits you derive from this over time with regards to the signalling effects of ketones in the body.
Rather than restricting all calories, a 50% caloric reduction in a time restricted eating window that was ketogenic this would
- suppress insulin,
- suppress mTOR (and IGF-1; both stimulators of growth in the body),
- reduce ATP signaling to the cells (energy signaling)
- reduce blood glucose levels.
- upregulate autophagy (though at this stage this is an educated guess as there is no way to test this).
The key is to focus on the glucose:ketone index, which you’d ideally keep between 1 and 2. IE that your ketones are no less than half of what your blood glucose is. Here’s an example of how to easily calculate this. Now, if you measure ketones and see a reading above 0.5 mmol/L, it is generally considered to be ‘nutritional ketosis’. The focus on the glucose:ketone index is more often used for a state of therapeutic ketosis and isn’t something I’ve discussed before. While it would take more thought to achieve this indicator, as we really have to consider both protein and carbohydrate intake, it isn’t impossible. I’ve been thinking about it and what might help:
- The time restricted eating and the caloric restriction are two ways to increase ketones without thinking about what is going in. Aiming for a 6-8 hour eating window for these five days, allowing for plenty of fasting time to upregulate ketone production.
- The use of ketogenic foods and drinks (such as coffee, raw apple cider vinegar, MCT oil and powder, coconut oil) that are known to help produce ketones.
- Use of supplements may help (such as phosphatidyl serine, reishi, ashwaganda) that help lower stress response that can occur transiently while shifting over to a ketogenic diet.
- Keeping the meals simple so you don’t have to think too hard about it – for ease, I would go for the same two or three meals across the five days.
- This approach is more intensive than a standard ketogenic diet, as I said, you are not just working on a diet and exercise regime to get you into ketosis, you are aiming for that maximum of 2 on the glucose ketone index.
- Exogenous ketones? Well, they might be beneficial – at least they have been shown to lower blood glucose when used alongside a ketogenic diet and exercise (in rodent models). That said, there may be varying results if using ketone esters compared to ketone salts (salts, such as Pruvit sachets, are more accessible, however they raise ketones by perhaps 1 mmol/L, compared to the 4-6 mmol/L seen in ketone esters. In addition, it might be that producing ketones (rather than administering them) is more therapeutic and beneficial. The jury is still out.
- Other questions? May be answered here in this FAQ section.
So those are my thoughts. I thought this was such a good option, I put together a protocol for it to show you how you could do it. Click here for more information and to sign up.
Mikki Williden, PhD 