Scientific Nutrition Update 47: Early Time Restricted Feeding

I just read a paper that changed many of my perceptions about intermittent fasting, which in the past I thought had no benefits in excess of or in lieu of calorie restriction.  I may be totally wrong.

Script (remember I ad-lib):

For today’s episode I am going to talk about a brand new study that just came out, directly in my wheelhouse because it is about a form of intermittent fasting.  It is called early time restricted feeding, and it is similar to other forms of intermittent fasting I have discussed in this podcast, but with one important difference, you stop eating around 2-3 pm.  I have for a while now said that intermittent fasting is just a tool for calorie restriction, that it does not have benefit in excess of or in absence of calorie restriction. I think I may have been wrong.

So this paper that changed my mind is a fascinating one, but we do need to be careful with it to make sure that we do not over-interpret it.  It was published a few days ago in Cell Metabolism and discussed a form of eating with a six hour feeding window like Martin Berkhan advocates for on LeanGains, but with the goal of finishing eating before 3 pm.  The potential benefit of this in theory is primarily circadian in nature. Better regulation of the circadian rhythm may help reduce certain stress markers, and oxidative damage, and it is possible that eating earlier in the day like this would help promote that improved circadian rhythm.  This study was looking specifically at 8 male subjects with prediabetes, and crossed the people over so they at different points were in both the normal eating and the intermittent fasting group. Now since you guys have listened to this show before, you already see some of the problems. 1. We are looking at only a single gender. 2. We are looking at only people with prediabetes. 3. We are looking at a very small number of subjects.  However, temporarily let’s look past all of that and see what the study suggests.

They found significantly improved insulin sensitivity, reduced blood pressure, reduced oxidative stress, improved beta pancreatic cell responsiveness, and even counterintuitively reduced appetite.  These results are honestly pretty incredible, for several reasons. First and foremost is the fact that neither group had any weight loss. This suggests to me that all benefits here are in the absence of calorie restriction, something I previously claimed to not believe in.  Furthermore, the fact that there was a reduction in appetite in the group that ate earlier. I have almost always in my personal fasting skipped breakfast and broken the fast with either lunch or dinner, because I knew from the past that once I started eating it can be hard for me to stop, so I tried to minimize the potential time where I could be eating.  However, what I did not consider is that this exact approach may have been contributing to the often ravenous hunger I was feeling. Perhaps most interesting to me here is the changes in insulin sensitivity in absence of weight loss. This suggests that for insulin sensitivity we do not just need to consider how much is eaten, and of what, but also when it is being consumed.  Furthermore, it suggests that a reduction of metabolic diseases like diabetes may be possible without the normally mandated weight loss with a shift to eating more in line with circadian rhythm.

Now I am going to be honest you guys, I am far from an expert on circadian rhythms.  I am studying as much as I can, and experimenting with it, like the blue blockers I wear now that I discuss in episode 31.  However, if you want to learn more about circadian treatments I would look into Dr. Lagakos of Calories Proper, because his work has been critical in me getting up to speed.  And do remember that for now this study is too small to generalize from, but the conclusion is interesting enough to me that I am planning on doing a personal experiment where I try to shift my eating early and see how my appetite changes.  If you learned something new please consider sharing this episode with a friend, remember to check out the work of both Dr. Lagakos and Martin Berkhan and thank you for tuning in.

Bibliography (I may not directly address these studies in the episode but I looked at them and thought they might be valuable):

https://www.cell.com/cell-metabolism/fulltext/S1550-4131(18)30253-5

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