A claim you hear on longevity podcasts

Do sugar cravings come from your gut?

The claim checked: Signals from the gut, below conscious detection, drive you to seek out sweet things regardless of taste Hear it at 49:01

What do the studies say?

Not enough evidence

Four animal studies, three in mice and one in flies, found sugar preference forms through gut signals, apart from sweet taste. None tested people.

None of these studies counts toward the badge yet. This point is about animals. Only human studies count toward a badge.

What was said on the podcast?

“the second pathway is what's called the post-ingestive reinforcing properties of sugar, which is really just a fancy nerd speak way of saying there are events that happen within your stomach and below your conscious detection, that are also driving you to seek out sweet tasting things, independent of their taste”
Andrew Huberman, Huberman Lab · Controlling Sugar Cravings & Metabolism with Science-Based Tools | Huberman Lab Podcast #64 · 49:01 on YouTube
Comes up in 6 episodes of the show.
Point 1 of 2 Not enough evidence

Sugar has post-ingestive reinforcing effects via a gut-to-brain signal, independent of taste

Agree 4

other primary study · 2020 · landmark

Not counted. An animal or lab study.

“Thus, although taste knockout animals cannot even taste sugar or the sweetener, they still learn to recognize and choose the sugar, most likely as a result of strong positive post-ingestive effects 17 .”

The gut-brain axis mediates sugar preference. Nature
Who: Adult mice (wild-type, TRPM5 KO and T1R2/T1R3 double KO sweet-taste knockouts, plus Cre-driver lines) of both sexes older than 6 weeks
PMID 32322067

other primary study · 2022 · landmark

Not counted. An animal or lab study.

“Here, we demonstrate that an animal’s preference for sugar over sweetener depends on duodenal neuropod cells.”

The preference for sugar over sweetener depends on a gut sensor cell. Nat Neurosci
Who: adult male and female mice (6-20 weeks; wild-type C57BL/6J, CckCRE_Halo, CckCRE_ChR2 and other transgenic lines), plus mouse and one human donor duodenal organoids
PMID 35027761

other primary study · 2010

Not counted. An animal or lab study.

“T1R3 KO mice, which are unresponsive to sugars in the mouth (7, 41, 44, 45), were fully responsive to the positive conditioning effects of sugar in the gut.”

Gut T1R3 sweet taste receptors do not mediate sucrose-conditioned flavor preferences in mice. Am J Physiol Regul Integr Comp Physiol
Who: Male C57BL/6J wild-type and T1R3 knockout mice, 9 wk of age, fitted with gastric catheters
PMID 20926763

Show 1 more Show fewer

other primary study · 2015

Not counted. An animal or lab study.

“Intriguingly, we observed that starved wild type flies initially selected sweeter L-glucose, but within 5 minutes, they started to choose nutritive D-glucose (Figure 7A).”

Nutrient Sensor in the Brain Directs the Action of the Brain-Gut Axis in Drosophila. Neuron
Who: Drosophila melanogaster (adult male flies, wild-type and genetic mutants)
PMID 26074004

Partly agree 0

None.

Disagree 0

None.

Point 2 of 2 Conflicting

This happens in humans as well as animals

One human study found a metabolic signal drives the reward value of carbohydrates; two human trials found no sign that post-oral signals taught a flavour preference.

Computed from 3 studies that test this point, each judged by two readers, in full. Sources land on both sides. 2 more studies are waiting for a full read and do not count yet.

Agree 1

other primary study · 2017

“Our results provide strong evidence that in humans, as in animals it is a metabolic signal that determines the reinforcing value of carbohydrates.”

Integration of Sweet Taste and Metabolism Determines Carbohydrate Reward. Curr Biol
Who: Healthy-weight young adults (mean age about 23-25) in New Haven, across four experiments
PMID 28803868

Partly agree 0

None.

Disagree 2

controlled trial · 2020

“Accordingly, we conclude that we found no evidence of flavour-nutrient learning and flavour-satiety learning.”

No evidence of flavour-nutrient learning in a two-week 'home exposure' study in humans. Appetite
Who: Young adults (mean age 25.6, 54.2% female, BMI 23.3) from the University of Bristol and local community
PMID 31765687

controlled trial · 2026

“Within the present experimental framework, post-oral signals of erythritol and sucrose did not affect reward responses, indicating that these effects may not be associated with FNL but rather with FFL or mere exposure.”

Erythritol, sucrose, and sucralose elicit similar reward responses after flavor preference learning in healthy humans. Physiol Behav
Who: Healthy young adults (10 women, 10 men; age 25.8 ± 7.5 years, BMI 22.3 ± 1.8 kg/m2), supertasters and non-tasters excluded
PMID 42184911

What else was said but not tested?

  • With sweet taste blocked, preference for the sugar drink returns after about 15 minutes
  • Mechanism: gut neuropod cells to vagus to nodose ganglion to NTS, triggering dopamine

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