Abstract 9262: Physical Activity, Nutritional Status and the Risk of Normal-weight Obesity in the US Population

Abstract

Purpose: Subjects with normal weight obesity (NWO), defined as normal BMI but high body fat (BF)%, are at increased cardiovascular risk. Factors contributing to NWO are not well studied. We hypothesized that NWO is associated with reduced physical activity and unhealthy eating patterns.

Methods: We analyzed 5942 people ≥18 years with normal BMI (18.5-24.9 kg/m²) from the NHANES III survey (1988-1994), a representative sample of the US population. Subjects were classified as NWO based on BF% (>35% in women and >25% in men). Leisure-time physical activity was measured with a standard survey. Subjects were stratified as INACTIVE (no physical activity reported), ACTIVE (3-6 METs for ≥ 5 times/week or >6 METs, ≥3 times/week), or insufficiently active (those who were not INACTIVE but did not meet criteria for ACTIVE). Total activity was expressed in METs/hr/month, assuming an exercise duration of 30 minutes for each day reported. A Healthy Eating Index was based on 24-hour dietary recall data. Analyses were weighted for the complex study design.

Results: Mean age was 43 years, 54.4% were men; 1170 people (19.7%) with normal BMI had NWO. Table shows demographics, physical activity and nutritional habits by group. After controlling for age, gender, poverty levels, smoking status and Healthy Eating Index, METs/hr/month was an independent predictor of NWO (OR per 100 MET/hours/month is 0.72(95%CI 0.60;0.88). People who were inactive and insufficiently active had higher odds of NWO as compared with active people (OR-1.47; 95%CI 1.10;1.96 and OR-1.60, 95% CI 1.25; 2.05, respectively). Also, strength training was independently associated with a decreased odds of NWO (0.63; 95%CI 0.44;0.89). Dietary pattern was not predictive of NWO.

Conclusions: Physical activity, particularly resistance exercise, but not diet, was associated with NWO independently of potential confounders. Promoting physical activity may be an important interventional strategy in these patients.