The Associations of Trunk Intramuscular Adipose Tissue Content with Dietary Intake and Eating Behavior in Younger and Older Japanese Women: A Pilot Study

Background/Objectives: Intramuscular adipose tissue (IntraMAT) is the ectopic fat which accumulates within skeletal muscle. The relationship between trunk IntraMAT content and dietary intake was shown to differ with age in men, but it remains unclear the relationship in women. Therefore, the present study investigated the associations of IntraMAT content with dietary intake and eating behavior in younger and older women. Methods: This cross-sectional study involved 24 young women aged 18 to 23 years (body mass index (BMI): 20.5 ± 2.3 kg/m2) and 25 older women aged 66 to 77 years (BMI: 21.7 ± 2.5 kg/m2) who participated. IntraMAT content was assessed by magnetic resonance imaging at the height of the 3rd lumbar vertebra. Dietary intake was evaluated using a self-administered diet history questionnaire. Eating behavior was evaluated by scores calculated using the eating behavior questionnaire in the guideline for obesity (2022). Blood properties related to metabolic syndrome were also measured. Results: In the younger group, IntraMAT content was significantly related to HDL cholesterol and insulin (rs = −0.411 and 0.415, p < 0.05). In the older group, IntraMAT content significantly correlated with the percentage of energy from protein, sense of hunger, and total eating behavior (rs = −0.410 to 0.412, p < 0.05). Conclusions: Trunk IntraMAT content may be related to dietary protein intake and eating behavior in the older group.