Weight-loss talks: What works (and what doesn’t)

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Original Research

Weight-loss talks: What works (and what doesn’t)

J Fam Pract. 2011 April;60(4):213-219

By

Kathryn I. Pollak, PhD

Stewart C. Alexander, PhD

Mary E. Cox, MD, MHS

William S. Yancy, Jr, MD, MHS

Christy Boling Turer, MD, MHS

Pauline Lyna, MPH

Truls Østbye, MD

Rowena J. Dolor, MD, MHS

James A. Tulsky, MD

Combining nutrition, physical activity, and weight loss advice may help patients reduce fat intake. Focusing solely on exercise may actually lead to weight gain.

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References

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Abstract

Background In primary care encounters, it is unknown whether physician advice on weight-related matters leads to patient weight loss. To examine this issue, we analyzed physician weight loss advice and measured corresponding changes in patients’ dietary intake, physical activity, and weight.

Methods Using audio-recorded primary care encounters between 40 physicians and 461 of their overweight or obese patients, we coded weight-related advice as nonspecific, specific nutritional, specific exercise, or specific weight. Physicians and patients were told the study was about preventive health, not weight. We used mixed models (SAS Proc Mixed), controlled for physician clustering and baseline covariates, to assess changes in diet, exercise, and measured weight, both pre-encounter and 3 months post-encounter.

Results When discussing weight, physicians typically provided a combination of specific weight, nutrition, and physical activity advice to their patients (34%). Combined advice resulted in patients reducing their dietary fat intake (P=.02). However, when physicians provided physical activity advice only, patients were significantly (P=.02) more likely to gain weight (+1.41 kg) compared with those who received no advice.

Conclusion When giving weight-related advice, most physicians provided a combination of lifestyle recommendations. Combining advice may help patients reduce their fat in-take. Physical activity advice alone may not be particularly helpful.

The US Preventive Services Task Force (USPSTF) recommends that physicians screen patients for obesity and offer intensive counseling and behavioral interventions to promote sustained weight loss.¹ Evidence suggests that physician counseling, including advice, can help patients to lose weight, increase physical activity, and improve diet.^2-9 However, little is known about what specific types of weight loss advice physicians give to patients, and whether some types are more effective than others at influencing behavior change.

We analyzed physician weight loss advice delivered in primary care visits and measured changes in patients’ dietary intake, physical activity, and body weight. We examined both the type of weight loss advice delivered and the impact of type of advice on weight and behavior change.

Methods

FAST TRACK

When physicians provided physical activity advice only, patients were significantly more likely to gain weight.

This study analyzed audio recordings from Project CHAT – Communicating Health: Analyzing Talk. The project was approved by the Duke University Medical Center Institutional Review Board.

Recruitment Physicians. We obtained consent from 40 primary care physicians in community-based practices and told them the study would examine communication around preventive health topics, not weight specifically.

Patients. We identified potential participants by reviewing scheduled appointments 3 weeks in advance. Eligible participants were at least 18 years of age, English-speaking, overweight or obese (body mass index [BMI] ≥25 kg/m²), cognitively competent, and not pregnant. After we obtained consent, a remotely located research assistant started a digital audio recorder as the patient entered the exam room. Immediately after the encounter, the research assistant administered a post-encounter survey to the patient and recorded the patient’s vital signs (N=461). Three months later, the research assistant met with the participant to record vital signs and administer a survey assessing changes in dietary fat intake and exercise (N=426).

Data coding
We coded advice into 4 broad categories: (1) nutrition advice, (2) physical activity advice, (3) specific weight loss advice, and (4) nonspecific weight loss/weight-related advice. We transcribed each piece of advice verbatim.

Nutrition advice consisted of 9 sub-categories: calorie/portion control, meal timing/planning, commercial diet plans, negative diet plans, increase fruits/vegetables, reduce sugar/carbohydrates, reduce fat/cholesterol, other micronutrient recommendations, and specific food items from multiple categories.

Physical activity advice consisted of 6 subcategories: walking, aerobic exercise, anaerobic exercise, exercise intensity, exercise duration, and exercise for comorbid conditions.

Specific weight loss advice consisted of 3 categories: weight loss behavior, weight loss for comorbid conditions, and referrals.

Nonspecific weight loss advice also consisted of 3 subcategories in which physicians provided no details about the general topics of nutrition, physical activity, or weight loss.

Two independent coders (CBT and MEC) assessed each piece of advice and double coded 20% of conversations for reliability. Cohen’s kappa was used to calculate inter-rater reliability for each code using Landis and Koch’s classification (0.21-0.40=fair agreement; 0.41-0.60=moderate agreement; 0.61-0.80=substantial agreement; 0.81-1.0=near-perfect agreement).¹⁰ Three advice categories achieved near perfect agreement: nutrition (kappa= 0.94; 95% confidence interval [CI] 0.82-1.0; 99.2% agreement), physical activity (kappa=0.91; 95% CI, 0.84-0.99; 98.6% agreement), and weight loss (kappa=0.95; 95% CI, 0.82-1.0; 99.7% agreement). The nonspecific weight loss advice category had slightly lower agreement but still achieved near-perfect agreement (kappa=0.82; 95% CI, 0.62-1.0; 99.2% agreement).

After all advice was coded, we placed conversations into 1 of 6 categories: (1) no advice given; (2) nonspecific advice only; (3) nutrition only; (4) physical activity only; (5) weight loss only; or (6) combination of nutrition, physical activity, and/or weight loss.