Normal Weight Obesity Associated with Enhanced Echo Intensity, Insulin Resistance, and Decreased Muscle Strength in Young Adults.

Abstract

Context: Obesity refers to the accumulation of excess body fat. Even individuals with a normal body mass index (BMI) of <23 Kg/m² but a high percentage of body fat have an increased risk for noncommunicable disease. This condition is referred to as normal weight obesity (NWO).

Aim: To assess the association between muscle strength, ultrasound-derived muscle thickness, insulin resistance, and echo intensity in NWO and normal weight nonobese (NWNO) young adults.

Methods and material: Eighty young adults of a normal BMI of 18.5 to 22.9 Kg/m² were recruited in this current study. Forty subjects with cutoff points of body fat percentage ≥ 20.6% for men and ≥ 33.4% for women were taken as NWO group and 40 were NWNO. Fasting glucose and insulin were used for calculating insulin resistance, sensitivity, and beta cell function. Ultrasonography (USG) was done to measure forearm radial and ulna muscle thickness. The echo intensity was measured from an ultrasound image as a mean pixel value using Adobe Photoshop. Subjects were tested for handgrip strength using hand dynamometry.

Results: Hand grip strength was higher in NWNO group, and subcutaneous fat thickness and echo intensity were higher in the NWO group. Glucose, insulin, and insulin resistance were significantly higher in the NWO group. Linear regression showed a significant correlation between ulna muscle thickness, forearm circumference, echo intensity, and insulin resistance with handgrip strength (r = 0.835 P < 0.001).

Conclusions: NWO adults have higher insulin resistance and echo intensity, indicating decreased muscle quality compared to NWNO individuals.