Dr. Andrew Huberman, Ph.D. is a Professor of Neurobiology and Ophthalmology at Stanford University School of Medicine. His lab focuses on neural regeneration, neuroplasticity, and brain states such as stress, focus, fear, and optimal performance.
Andrew Huberman explains how sugar is sensed, metabolized, and used in the body, the connection between sugar, dopamine, and cravings, and most importantly – science-based approaches to blunt sugar cravings.
Host: Andrew Huberman (@hubermanlab)
Note: For full access to publications that are behind a paywall, check out Sci Hub.
Ghrelin increases how long it’s been since we ate last and makes us hungry by interacting with other brain areas
When we eat, ghrelin levels drop
Our blood glucose (blood sugar) rises to varying degrees depending on what we ate
Our brain doesn’t function well if blood sugar is too high or too low
Insulin from the pancreas regulates the amount of glucose in the bloodstream
The brain is a chief organ for glucose metabolism: our neurons basically run on sugar – not to say you should eat a lot of sugar
Glucose is the preferred source of energy for the brain and nervous system: in a fasted state your body uses fuel available to neurons based on intake the previous day
Fructose is handled differently in the body than glucose: fructose has the ability to reduce hormones and peptides whose main job is the suppress ghrelin (the hormone that makes us hungrier)
Fructose itself is a good fuel source but can increase hunger
Fructose in fruit has been improperly demonized: the concentration of fructose in fruit is so low that unless you are consuming an extremely high volume, or as part of a high sugar meal, you don’t really gain weight from sugar
High fructose corn syrup is 50% fructose as compared to fructose in fruit which is 1-10% on the high end
Mangoes have the highest amount of fructose among any fruit
The case for reducing or eliminating sugary drinks: if glucose is replaced with fructose in sugary drinks, there’s a decrease in type 2 diabetes and metabolic syndrome associated with high fructose corn syrup, even if the same number of calories is ingested
Because we have so many systems in our nervous system that need sugar, we have systems set up to seek out foods that have sugar
For every function in your body, there are two or more parallel pathways that ensure that particular behavior takes place
Two parallel pathways in sugar consumption: (1) the conscious pathway related to taste or perception of taste that leads to seeking behavior; (2) subconscious the other pathway related to the nutritive component of glucose
Getting sweet things into the body has a bit to do with the taste but just as much to do with the nutritive component for the nervous system those sweet things carry
When you’re craving something sweet, you’re craving the taste and neurons are craving the nutritive component
Strength of subconscious pathway: if you eliminate the perception of sweet taste in the mouth, the preference for the sweet beverage still comes back in about 15 minutes
The preference for sugar-containing foods is in part preference, part “post-ingestive effect” by neuropod cells
Nerve cells (specifically called neuropod cells) in the gut are collecting information about what’s there and send that information up to the brain via the vagus nerve
Neuropod cells sense nutrients, particularly sugar, which activates areas of the brain that increase dopamine and cause you to seek out more of that food
Sugar has a potent ability to activate the dopamine pathway – especially if ingested through sweet liquid
Eating sugary food shifts your perception of food in general by modulating dopamine
When you eat something sweet, your perception of food shifts and seeks more sugary things and more food in general
Remember: any time we engage in behavior or ingest something that increases dopamine, there is a subsequent increase in the neural circuits that control pain, frustration, and wanting
If you eat the chocolate, your brain and body orient towards wanting more
The longer it’s been since you indulged in something you really enjoy, the greater the dopamine increase and the greater the subsequent pain or frustration after
Measurement of glycemic indices of foods are often done in isolation without other foods which can actually impact the metabolism of that food
Glycemic index isn’t really the holy grail of food measurement because of the limitation of how it’s derived – for example, ice cream has a lower glycemic index than mangoes or table sugar – but that’s really because of the impact of fat on sugar metabolism
A sharp rise or high elevation in blood glucose is a much more potent signal a moderate or slow rise in blood glucose
The glycemic index is useful in assessing how hard or fast we’re pushing on the parallel pathways/dopamine pathway
Tip: consume other foods (ideally fiber – which may be strange) along with sweet foods to reduce glycemic index and slow or blunt release of dopamine
Particular flavors (i.e., artificial sweeteners) can be conditioned to cause an insulin release
Study example: if you typically have a diet soda, cheeseburger, and fries for lunch – if you just have a diet soda alone (so technically no calories consumed), that diet soda alone will increase glucose because you conditioned the taste of artificial sweetener to a rise in blood glucose
The changes in blood glucose were so significant, particularly in children, that the experiment had to be stopped
Artificial sweeteners, particularly sucralose disrupt the microbiome in high doses
Any flavor associated with glucose spike can be conditioned
Try supplementing with glutamine incapsule orpowder form – but start slow, it can cause some gastric distress (of course, talk to a doctor first)
Ingesting something sour can change the neural response to the taste of sweet foods
A few tablespoons of lemon juiceor lime juice before, during, or after eating a large meal or lots of sweets could blunt glucose (don’t try this is fasting so you don’t make yourself hypoglycemic)
Cinnamon can also blunt glucose response by way of reducing gastric emptying time (don’t consume more than 1.5 teaspoons per day)
Berberineis on par with metformin to lower blood glucose but is over the counter – be careful taking on an empty stomach as it may cause hypoglycemia
By blunting blood glucose, over time sugar cravings will increase
SLEEP! Particular phases of sleep are associated with sugar metabolism – less sleep or sleep deprivation triggers an increase in the sugar craving
Sugar consumption is not good for people with ADHD or attentional deficits
When kids get beyond 4 sugary drinks per week, symptoms of existing ADHD are exacerbated
Tip: Omega-3 supplementation has been shown to ameliorate some symptoms of ADHD