Background

Obese or overweight young adults have higher risk of developing risk factors for serious chronic conditions later in life. Obesity is a heterogeneous condition for which information regarding phenotypes may lead to novel means of targeted prevention and treatment.

Methods

The Early Adult Reduction of weight through LifestYle intervention (EARLY) is comprised of separately funded randomized controlled trials targeting weight loss or weight gain prevention in 18-35 year old participants. The studies contributed common measures to a shared database. Using this resource, latent class analyses of 37 baseline characteristics (eating behaviors, physical activity, sedentary time, weight management behaviors, sleeping patterns, tobacco use, alcohol consumption) were used to identify phenotypes in a sample of 1692 participants with body mass index (BMI) of at least 25 kg/m2.

Results

The 5 phenotypes are characterized by: 1) relatively poor eating habits but high total physical activity (n=596), 2) low physical activity and high sedentary behavior (n=144), 3) high consumption of diet and sugar sweetened beverages (n=130), 4) cigarette smokers and alcohol consumers (n=110), and 5) relatively healthy eating habits and high leisure-time physical activity (n=712). The last and most common phenotype has the highest percentage of females (71%), the highest percentage of never smokers (74%), and the largest percentage of overweight but not obese participants (53%).

Conclusions

Obesity phenotypes in young adults can be differentiated by eating habits, physical activity, smoking and alcohol use. The largest group, with the highest percentage of overweight but not obese members, have higher percentages of members reporting better eating habits and more leisure time physical activity than other phenotypes. But since all have BMI at least 25 kg/m2, lifestyle improvements are still needed. These behavioral phenotypes potentially provide specific targets for weight loss interventions.