Single-slice quantitative magnetic resonance imaging (MRI) of the thigh for differential assessment of fasting-related body composition changes.
F Ensle, N Derron, C J Huang et al.
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In 30 seconds
This prospective substudy of a randomised clinical trial assessed whether single-slice quantitative thigh MRI could estimate whole-body composition and detect changes after a month of fasting interventions. It included 66 non-obese participants assigned to control, alternate-day fasting, or time-restricted feeding groups. Extensor muscle area predicted whole-body muscle mass measured by whole-body MRI and bioimpedance, with R² values of 0.77 and 0.72, respectively. Thigh fat fraction and intermuscular adipose tissue were weaker predictors of visceral fat, and neither fasting regimen produced statistically significant changes in thigh measurements versus control.
Key findings
- Extensor muscle area predicted whole-body muscle mass with R² = 0.77 by whole-body MRI and R² = 0.72 by bioimpedance.
- Thigh fat fraction and intermuscular adipose tissue estimated visceral fat volume weakly to moderately (R² = 0.15 to 0.43).
- Neither fasting regimen significantly changed thigh muscle area, fat fraction, or intermuscular adipose tissue versus control (all P≥0.45).
Why it matters
A single-slice thigh MRI may offer a practical imaging measure for estimating whole-body muscle mass, while its estimates of visceral fat are less reliable. The absence of detectable thigh tissue changes in this study also cautions against assuming that short-term fasting-related body-composition changes will be apparent in these local MRI measures.
What to keep in mind
The intervention lasted one month, and the study found no statistically significant fasting-related changes in the thigh measures; the abstract does not report longer-term outcomes.