(P13-11-26) Lifestyle Factors That May Predict the Normal Weight Obesity Phenotype

Objectives: Normal weight obesity (NWO) is a phenotype in which a person has a normal body mass index (BMI) but elevated body fat. People with NWO have an increased risk for cardiometabolic disease, but little is known about the etiology or treatment of NWO. The purpose of this research is to identify potential lifestyle-related determinants, such as diet, physical activity, and alcohol consumption, of NWO in young men.

Methods: This trial includes 3 groups (n = 16/group; age 18-39 years): normal-weight lean (NWL; BMI 18.5-24.9 kg/m2, body fat < 25 %), NWO (BMI 18.5-24.9 kg/m2, body fat > 25 %), and obesity (OB; BMI ≥ 30 kg/m2, body fat > 25 %). All participants completed baseline testing, including a submaximal aerobic capacity test to predict VO2max, body composition scan with dual-energy X-ray absorptiometry (DXA), 3-day diet log, and 3 days of accelerometer wear.

Results: BMI between NWL (22.8 ± 2.5 kg/m2) and NWO (23.1 ± 0.8 kg/m2) was not different (p = 0.92), but the OB group was significantly greater than both groups (34.5 ± 4.1 kg/m2; p < 0.0001). Body fat percentage for all three groups (NWL, NWO, OB) was significantly different (19.8 ± 2.9 %, 29.1 ± 2.0 %, 35.1 ± 5.0 %; p < 0.0001). Estimated VO2max was significantly greater in the NWL group (33.8 ± 6.7 mL/kg/min) compared to the OB group (27.0 ± 9.3 mL/kg/min; p = 0.02) but not compared to the NWO group (29.1 ± 4.5 mL/kg/min). NWO was significantly more sedentary than NWL (p = 0.03). NWO tended to accumulate fewer steps (6298 ± 2142 steps/day) than NWL (8516 ± 3559 steps/day) and OB (7135 ± 2722 steps/day), but this was not significantly different. Food logs revealed significantly greater protein intake in the NWL group (121.3 ± 42.2 g) compared to the NWO (86.3 ± 24.1 g) and OB groups (90.4 ± 30.5 g; p < 0.05). No other diet variables were different. Alcohol intake between groups did not significantly differ but tended to be more common in the NWO group (60% regularly consumed) compared to NWL (44%) and OB (38%).

Conclusions: In this ongoing study, young men with NWO engage in significantly more sedentary time and consume less protein than lean peers. NWO men also tended to be less active, drink more alcohol, and have less aerobic capacity, but these were not significantly different. More data is needed in this area of research.

Funding Sources: American Heart Association Institutional Research Enhancement Award (25AIREA1377732)