Measures
Dietary fat and fiber intake. We assessed dietary fat intake at baseline and at 3 months using the 22-item Fat- and Fiber-Related Diet Behavior Questionnaire.11,12 Questions about frequency of food selections included, “When you ate dessert, how often did you eat only fruit?” and “When you ate chicken, how often did you take off the skin?” We averaged responses into a total score wherein 1 reflected higher fiber, lower fat food choices; a score of 4 reflected lower fiber, higher fat choices (α=0.74 at baseline and α=0.77 at 3-month follow-up).
Physical activity. We measured physical activity (baseline, 3 months) using the Framingham Physical Activity Index.13 Participants recalled the average number of hours spent engaged in various daily activities (sleeping, working, leisure) and the level of activity for each (sedentary, slight, moderate, or heavy). The composite score accounts for activity duration and intensity.
Anthropometrics. We measured patient weight (baseline, 3 months) and height (baseline only) using a calibrated scale and portable stadiometer. Patients removed shoes, outerwear, and belongings from their pockets before being weighed.
Analysis
We analyzed data using SAS (SAS Institute, Inc., Cary, NC). We assessed the association between type of advice and weight loss, improvement in dietary fat intake behaviors, and increase in physical activity between baseline and the 3-month follow-up visit. We used PROC MIXED to fit general linear models; we incorporated responses into these models from all participants who provided measurements for at least one time point. This modeling framework yields unbiased estimates when missing data are unrelated to the observed variable.14
Primary predictors: (1) type of advice (none, nonspecific, nutrition, physical activity, weight loss, and combination), (2) time since baseline visit, and (3) time by type of advice interaction. All models included a priori defined patient, physician, and visit-related covariates that were theoretically or empirically related to changes in the outcomes (weight, physical activity, or dietary fat in-take). The 14 patient covariates were sex; age; race; high school education; economic security (enough money to pay monthly bills); over-weight (BMI, 25-29.9 kg/m2) or obese (BMI ≥30 kg/m2); actively trying to lose weight (yes/ no); motivated to lose weight (Likert scale 1-7); comfortable discussing weight (Likert scale 1-5); confident about losing weight (Likert scale 1-5); and patient-reported comorbid conditions of diabetes, hypertension, arthritis, and hyperlipidemia.
The 9 physician covariates were sex; race; years since medical school graduation; specialty (family vs internal medicine); self-efficacy (Likert scale 1-5); barriers for weight counseling (Likert scale 1-5); comfort discussing weight (Likert scale 1-5); insurance reimbursement concerns (Likert scale 1-5); and prior training in behavioral counseling (yes/no). Finally, 2 visit-level covariates were included: minutes spent addressing weight issues and visit type (preventive vs chronic).
Results
Sample characteristics
Of the 40 physicians, 19 were family physicians and 21 were internists. More than half of the physicians were female (60%), and 85% were white. Mean age was 47.2 years and mean BMI was 24.9 kg/m2. Of the 461 patients, 66% were female, 65% were white, 35% were African American, and two-thirds had post-high school education (TABLE 1). Mean patient age was 59.8 years; only 4% of the patients were new to their physicians.
TABLE 1
Patient characteristics (N=461)
| % or mean (SD) | |
|---|---|
| Race | |
| White/Asian/Pacific Islander | 65% |
| African American | 35% |
| Female | 66% |
| Age, y (missing=1)* | 59.8 (13.9) |
| BMI, kg/m2 (missing=1)* | 33.1 (7.1) |
| Education (missing=1)* | |
| Post-high school | 67% |
| Income (missing=37)* | |
| $45,000 or less | 48% |
| High financial burden (missing=13)* | |
| Pay bills with trouble | 14% |
| Diagnosed with: | |
| Diabetes | 31% |
| Hypertension (missing=1)* | 69% |
| Hyperlipidemia (missing=1)* | 56% |
| Arthritis | 47% |
| New patient | 4% |
| BMI, body mass index; SD, standard deviation. * Missing data at baseline. | |
Frequency of advice
Physicians gave some type of weight-related advice in 63% of the encounters. They combined types of advice in 34% of all conversations, provided physical activity advice only in 13%, nutrition advice only in 8%, nonspecific advice in 5%, and weight loss advice only in 3%. Many times when physicians gave advice, it was centered on self (eg, “I need you to do X” or “What will it take for me to get you to do Y?”).
Nutrition advice most commonly pertained to specific food items from multiple categories (27% of conversations). Physicians also advised patients to reduce sugar/carbohydrates, control calories and portions, add other micronutrients, eat more fruits/vegetables, and eat meals more frequently.
Walking was the physical activity topic discussed most frequently, followed by exercise duration, exercise for comorbidities, aerobic activities, exercise intensity, and anaerobic exercise. The most common specific weight loss topic was weight loss behavioral advice, followed by weight loss for comorbid conditions. Physicians rarely provided referrals to weight-loss programs.