In this first prevalence study of NES based on interviews among obese persons with type 2 diabetes, the observed rate of 3.8% was lower than expected given rates of at least 9% in other obese samples (6
). Houston’s participants were more likely to have a diagnosis of NES than those in Philadelphia or Minnesota. It is worth noting that their rate of 7.4% is similar to previous prevalence studies of NES (5
) in obese and diabetic clinical samples and that the other sites’ figures were closer to rates found in the general population (14
). The assessment method, i.e., using a cutoff score of 25 on the NEQ, could have influenced the low rates as well. This method identified cases as positive only if they had global night eating symptoms, because it is unlikely for someone who reported only evening hyperphagia and not nocturnal ingestions to score 25 or higher.
The prevalence of BED (1.4%) in this study was also lower than previously reported in some studies (8
), although not much different from rates of 2.5% (13
) and 3.7% to 5.3% (12
) reported by others. Age likely plays a role in these lower prevalence rates. The sample in this study averaged 60 years of age, which is older than other studies of BED prevalence to date. In studies with participants in their mid-to-late 50s (11
), only one (11
) found substantially higher rates of BED (13.5%) than this study. There have been no prevalence studies of NES in older, clinical populations, but epidemiologic data suggest that night eating behavior is least common among persons >65 years of age, with those respondents being 2.7 to 3.6 times less likely to report night eating than younger age groups (32
). There may also have been a “healthy volunteer effect” among this Look AHEAD cohort, because volunteers interested in participating in an 11-year study may be more health conscious than diabetics in the general population.
Diagnoses of BED and NES were related to higher levels of depressed mood, as reported in previous studies (8
). BED and NES participants endorsed comparable levels of eating disordered attitudes and behaviors on the EDE-Q, with the exception of the eating concerns subscales, on which the BED group had significantly greater pathology than the NES group which, in turn, had significantly higher pathology than the No Eating Disorders group. This pattern is similar to a previous study comparing eating disordered pathology among participants with BED, NES, and an overweight/obese comparison group (17
Obese diabetic individuals with BED or NES had higher current and lifetime BMIs and reported that their weight problems began earlier in life than participants without an eating disorder. They were also younger than participants without eating disorders, and there was a trend showing a younger age of diagnosis of their type 2 diabetes, perhaps influenced by the presence of an eating disorder, as noted by Kenardy et al. (11
). The BED and NES participants could also be more prone to help-seeking in an attempt to treat their diabetes earlier than the other participants or to get assistance in gaining control over their eating patterns.
Despite the BMI and age differences, physiologic health variables did not differ, suggesting that the presence of BED or NES does not significantly impact diabetes-related health measures, such as HbA1c
, waist circumference, and triglyceride levels. Previous studies also found no significant differences in HbA1c
among individuals with type 2 diabetes and BED (8
). However, the previous study of night eating among type 1 and type 2 diabetic patients found that evening hyperphagia was a significant predictor of HbA1c
>7, as well as obesity and having two or more diabetes complications (19
). These conflicting results could be caused by the mixed diagnostic group and younger age of the participants in the previous study.
The odds of diagnosis for BED and NES did not differ by sex, race, or any other health variable measured here; these disorders affect both men and women and are present across different racial and ethnic lines. Younger age at enrollment (57 vs. 60 years) was the only variable predictive of an eating disorder diagnosis among individuals with type 2 diabetes.
Strengths of this study include the geographic diversity of the sample, an interview-based diagnostic system, and the inclusion of a random sample of false-negative interviews. Comparing those with BED and NES separately was challenging because of the low prevalence rates and because some variables of interest were not available for non-randomized participants. Interview completion rates were likely affected by the nature of phone interviews or by lack of interest by participants who were not randomized into the larger Look AHEAD study.
It remains unknown how the presence of BED and NES will impact long-term weight loss efforts in the Look AHEAD study. There are indications that behavioral weight control programs reduce eating disordered pathology among individuals with BED (33
), but there are no data for their effect on NES. Referral to mental health or specialized eating disorders professionals for persons with BED and NES may be warranted if patients are distressed about these conditions and if the conditions are affecting their diabetes control. Continued observation of this sample will answer these important questions. Future research should also continue to explore the relationship between night eating patterns and diabetes complications.