THE ARISING · Longevity & Healthspan
Late Chronotype Linked to Metabolic Risk and Gut-Barrier Differences
An observational analysis of 87 adults with obesity linked late chronotype with greater metabolic syndrome burden. Gut permeability and inflammatory markers also varied with circadian habits; the study does not establish causation.
The work is an observational analysis of participants drawn from a randomized clinical trial. All 87 adults had a body mass index above 30. Their mean age was 42.5 years. The team, led by Faraz Bishehsari at UTHealth Houston, looked at two body-clock habits: chronotype, meaning whether a person naturally runs early or late, and how close to sleep time they ate.
Metabolic syndrome is a cluster of problems that includes obesity, insulin resistance, abnormal blood fats and high blood pressure. It raises the risk of cardiovascular disease, stroke and type 2 diabetes. The researchers split participants into a lower-risk group with zero or one feature and a higher-risk group with two or more.
Late chronotype was common: 59 of 87 participants (67.8%) were night owls. Of these, 42 (71.2%) were in the higher-risk group, compared with 13 of 28 early types (46.4%). Late eating was even more common. Some 66 participants (75.9%) were classed as late eaters, and 39 of them (59.1%) were in the higher-risk group.
The two habits together pointed the same way. The share in the higher-risk group rose from 6 of 14 (42.9%) among early types who ate early to 16 of 22 (72.7%) among late types who ate late. That combined-phenotype trend did not reach conventional statistical significance (p = 0.07).
To look beneath the clinical labels, the team built a composite metabolic-inflammatory score from 15 blood measures, including cytokines, metabolites and sugar-chain structures on antibodies. The score separated the two risk groups well in within-cohort testing, with an area under the curve of 0.918. Higher scores were tied to older age and poorer diet quality.
Specific markers lined up with the habits. Late chronotype was linked to higher interferon gamma, an inflammatory signal, and lower levels of the amino acid tryptophan. Late eating was linked to higher levels of the immune-signalling chemokine CCL8 and to a distinct antibody sugar profile.
The gut barrier is where the story turns. Gut permeability, measured with a sugar absorption test, was higher in the higher-risk group. Circadian misalignment was associated with increased permeability and inflammation, and the link was stronger in participants whose guts were already more permeable. Beta-glucan, a marker of fungal material crossing the gut wall, was higher in the higher-risk group.
These patterns went with lower levels of bacteria associated with short-chain fatty acids, compounds gut microbes make that support the gut lining. In an exploratory analysis, participants whose permeability changed after a microbiome-targeted intervention showed matching changes in these bacteria.
The main analyses used baseline measurements, so they cannot say whether late schedules led to the gut and inflammation findings. Medical Xpress framed the results as showing how late habits may weaken the barrier. The paper reports associations.
Future trials will need to test whether changing circadian habits or gut-barrier function improves metabolic outcomes.