While people with obesity have been found to chew fewer times and for shorter durations, few studies have quantitatively evaluated mastication among this group. This study examined the relationship between the mastication characteristics of people with obesity and the factors correlated with obesity. To this end, 46 people with obesity and 41 healthy participants placed an earphone-style light sensor in the aperture of their outer ear. We also examined the partial correlation between this, their body composition, and various biochemical markers by gender. A two-way analysis of variance (ANOVA) regarding the masticatory index, gender, and the presence/absence of obesity for all three food items revealed the main effects in the gender difference and the presence/absence of obesity. Additionally, the number of times the salad was chewed showed an interaction between the gender and the presence/absence of obesity. In the BMI-corrected partial correlation analysis of the chewing index and the glucose/lipid metabolism index, the chewing time and the number of chews of all the food items negatively correlated with hemoglobin A1c(HbA1c), fasting plasma glucose (FPG), immunoreactive insulin (IRI), and homeostasis model assessment of insulin resistance (HOMA-R) in the female obese group. These findings might be used in weight-loss interventions for men with obesity and treatments that target the metabolic function among women with obesity.

Hydrogen has antioxidant and anti-inflammatory properties that may attenuate perioperative stress responses. However, its clinical impact on postoperative recovery remains unclear. This randomized, double-blind, placebo-controlled trial evaluated whether perioperative hydrogen inhalation improves early recovery after hepatectomy. Sixty-eight patients undergoing elective hepatectomy were randomized (1:1) to receive 5% hydrogen gas or placebo air via nasal cannula from postoperative day (POD) 1 to POD7. The primary endpoint was the total Quality of Recovery-40 (QoR-40) score on POD3, analyzed at α = 0.2 with 80% confidence intervals in accordance with the pre-specified statistical analysis plan. Secondary and exploratory outcomes, analyzed at α = 0.05, included postoperative liver function, oxidative stress markers, and QoR-40 subdomain scores. Analyses were performed in the modified intention-to-treat population using the Mann–Whitney U test. Sixty-four patients (hydrogen, n = 31; placebo, n = 33) were analyzed. At POD3, the median QoR-40 score was 192.0 (184.0–198.0) vs. 163.0 (140.0–190.0) (p < 0.001), indicating significantly better early recovery in the hydrogen group. As supportive findings, prothrombin activity was higher with hydrogen (85.0% vs. 76.2%, p = 0.005), and QoR-40 subdomain analysis showed significantly higher emotions and physical independence scores, whereas comfort, pain, and patient support domains showed no difference. No other between-group differences were observed in biochemical parameters or urinary 8-OHdG levels. Perioperative hydrogen inhalation significantly improved early postoperative recovery after hepatectomy, primarily through psychophysical domains of well-being. These findings suggest that hydrogen may selectively enhance emotional stability and functional independence during the early recovery phase.