Intermittent Fasting: Effects on Dopamine

Nov 18, 2023

Andrew Huberman discusses the psychological and neurochemical responses that occur during fasting and how they reinforce the practice.

When people fast, many report a state of mental clarity and a shift in their enjoyment towards the act of fasting itself rather than the food they eventually consume.

As Huberman explains, fasting triggers dopamine release, not from the anticipation of food, but from the act of deprivation. This shift is key to understanding why fasting becomes a reinforcing activity.

The power of belief is also influential in fasting.

As fasters tell themselves about the potential health benefits they might be receiving – such as improved blood lipid profiles, better glucose management, and enhanced insulin sensitivity – these beliefs enhance the rewarding nature of fasting.

Although the research is still emerging, fasting is thought to induce biological processes like autophagy, which could contribute to its perceived health benefits.

Huberman dives deeper into the role of dopamine in reinforcing behaviors that we consider beneficial, like fasting.

The forebrain, responsible for knowledge, interpretation, and rational thought, can shape the reward circuits that are typically associated with more primitive behaviors.

Emphasizing how knowledge can change our chemical responses, he suggests that believing a behavior is good for us can enhance its beneficial effects at a neurochemical level.

Furthermore, he references a study that shows the reinforcement of pre-existing beliefs can itself trigger dopamine release.

This reveals our dopamine pathways’ high sensitivity to subjective interpretation, directly influencing how we derive pleasure from our experiences.

Huberman’s insights extend to the way we perceive and enjoy food. Our dopamine levels are influenced by previous experiences; for example, tasting something sweeter or more savory than what we previously enjoyed can diminish our enjoyment of the former.

However, briefly abstaining from highly palatable foods can reset our taste perceptions, making simpler foods like broccoli taste delicious with minimal seasoning.

Transcription

“One straightforward example of learning to attach dopamine to effort and strain as opposed to a process or a reward that naturally evokes dopamine release is so-called intermittent fasting. I know this is very popular nowadays. Some people like to do intermittent fasting, some people don’t. Some people have a 12-hour feeding window every 24 hours. Some people do long fasts of two to three days even.

I personally don’t monitor a feeding window with a lot of precision. I tend to skip one meal a day, either breakfast or lunch, and then I eat the other two meals of the day depending on which meal I skip. So it’s either breakfast, lunch, and maybe a little something in the evening, or I’ll skip breakfast and do lunch and dinner and so on.

Many people are now eating this way in part because many people find it easier to not eat at all than to eat a smaller portion of some food. And that has everything to do with the dopamine reward evoking properties of food. When we ingest food or when we are about to ingest food, our dopamine levels go up. And typically when we ingest food, if it evokes some dopamine release, then we tend to want even more food.

Remember, dopamine’s main role is one of motivation and seeking. And what dopamine always wants more of is more dopamine, more activity or thing that evokes more dopamine release.

Well, let’s just look at fasting from the perspective of dopamine schedules and dopamine release and peaks and baselines. Typically when we eat, we get dopamine release, especially when we eat after being very hungry. If you’ve ever gone camping or you’re very, very hungry, the food tastes that much better. And that’s actually because of the way that deprivation states increase the way that dopaminergic circuits work.

Our perception of dopamine is heightened when the receptors for dopamine have not seen much dopamine lately. They haven’t bound much dopamine. So when you fast, fast, fast, fast, fast, and then you finally eat, it evokes more dopamine release. So this is the big reward that comes at the end, even bigger because you deprived yourself. This is true for all rewarding behaviors and activities.

By the way, the longer you restrict yourself from that activity, the greater the dopamine experience when the dopamine is finally released because of an up-regulation of the receptors for dopamine. But I just spent five minutes or more telling you that you should avoid too much reward at the end and you should actually focus on the dopamine that you can consciously evoke from the deprivation strain and effort.

And in fact, this is what happens for many people that start doing fasting and take a liking to it. Many people say that their state of mind when they fast is clear, that they actually start to enjoy the period of fasting. In fact, some people start pushing out their eating window or skipping entire days of eating more and more in order to get deeper into that state of mind where surely it’s not just dopamine, but dopamine is released.

They will track their clock. Oh, I’ve been fasting 12 hours, 16 hours, et cetera. They are starting to attach dopamine release or create dopamine release from the deprivation, not from the food reward itself. And this, I think, makes it an interesting practice and one that certainly has been practiced for centuries in different cultures and different religions of deliberately restricting food, not just to increase the rewarding properties of food itself but also to increase the rewarding properties of deprivation.

And I should emphasize that a lot of the subjective aspects of the knowledge of the benefits of fasting serve as reinforcing dopamine amplifying aspects to fasting, meaning if somebody does intermittent fasting and they are deep into their fast and they’re telling themselves, oh, my blood lipid profiles are probably improving and my glucose management is probably improving, my insulin sensitivity is going up and I’m going to live longer, all these things that have some basis from animal studies and some basis or not from human studies, it’s all kind of still in emerging literature, but it does seem to be pointing in that direction that fasting can encourage things like autophagy, the engulfment of dead cells and things of that sort.

Well, as people tell themselves these things, they are enhancing the rewarding properties of the behavior of fasting. And so this is a salient example of where knowledge of knowledge can actually help us change these deep primitive circuits related to dopamine. And this illustrates how the forebrain, which carries knowledge and carries interpretation and rational thought, can be used to shape the very circuits that are involved in generating reward for what would otherwise just be kind of primitive behaviors, hardwired behaviors. And that’s the beauty of these dopamine circuits. And that’s the beauty of dopamine.”