Motivational Interviewing

Motivational Interviewing has been shown to be more effective than standard care in eliciting change towards more healthy diets.  Hollis et al. (2015) used the technique with 28 premenopausal women ages 44-50, with the goal of influencing their diets to be less likely to result in weight gain as they entered their menopausal years.  The control group of 26 women were given similar instructions but in a written format rather than interacting with the motivational interviewers.  They found that after 12 months, the women who had participated in the motivational interviewing program were getting significantly more iron and potassium in their diets, as well as more servings of fruit.  During the 12 months they had received four hour long sessions with a dietitian, as well as another with an exercise physiologist. 

Spencer and Wheeler (2016) conducted a systematic review looking at 15 studies where motivational interviewing was investigated as an intervention for cancer patients or cancer survivors.  Three of the studies were aiming to improve fruit and vegetable consumption, and these three studies found that motivational interviewing was indeed able to help participants change their dietary habits as measured by statistically significant increases in fruit and vegetable consumption.  The authors note the the effect size, measured by Cohen’s D or Hedges’ G, was strong enough to be clinically relevant. In fact, the Djuric et al. (2011) study found that servings of fruits and vegetables increased from 4.4 to 7.5 among breast cancer treatment patients who participated in motivation interviewing around this recommendation.  Spencer and Wheeler (2016) describe motivational interviewing’s emphasis on the role of the participant in strategizing ways to integrate the desired new behaviors into their existing routines.  The studies they reviewed encompassed quite a range of ways that n which the motivational interviewing sessions were conducted, and they found the technique to be effective even when done over the phone rather than in person and even if the interviewers had received limited training. 

In the Djuric et al. (2011) study, each of the 13 participants in the motivational interviewing group was scheduled for a total of 19 phone calls over the course of a year from a dietitian trained in both motivational interviewing and social cognitive theory.  On average 17.4 of these calls were completed, with 13 being the best number completed.  The goal of the intervention was to increase fruit and vegetable intake above 7 servings per day, not counting potatoes, so the mean of 7.3 at 12 months had achieved this.  This was measured by a dietary recall instrument where the participants were not told which day to expect it. 

References:

Djuric, Z., Ellsworth, J. S., Weldon, A. L., Ren, J., Richardson, C. R., Resnicow, K., Newman, L. A., Hayes, D. F., & Sen, A. (2011). A Diet and Exercise Intervention during Chemotherapy for Breast Cancer. The Open Obesity Journal, 3, 87–97. 

Hollis, J. L., Williams, L. T., Morgan, P. J., & Collins, C. E. (2015). The 40-Something Randomised Controlled Trial improved fruit intake and nutrient density of the diet in mid-age women. Nutrition & Dietetics, 72(4), 316–326. 

Spencer, J. C., & Wheeler, S. B. (2016). A systematic review of Motivational Interviewing interventions in cancer patients and survivors. Patient Education and Counseling, 99(7), 1099–1105.