Abstract
Background
Behavioral weight loss interventions utilizing portion controlled meals (PCMs) produce significant decreases in weight. However, the impact on diet quality during weight maintenance is unknown. To assess the influence of a weight management intervention employing PCMs and increased physical activity on diet quality during weight loss and weight maintenance.
Methods
197 overweight and obese adults (67% women; BMI = 34.0±4.6 kg/m2; age = 46.1± 8.9 yrs.) completed an 18-month trial. The weight loss phase, 0–6 months, consisted of energy restriction achieved using PCMs plus fruits and vegetables and increased physical activity. During weight maintenance, 6–18 months, participants consumed a diet designed to maintain weight loss. Body weight and dietary intake were assessed at baseline, 6, 12, and 18 months. Healthy Eating Index-2010 (HEI) was calculated using data obtained from 3-day food records.
Results
Body weight was 14.3 ± 6.6%, and 8.7 ± 8.0% below baseline at 6 and 18 months, respectively. The HEI-2010 score following weight loss,(66.6 ± 9.4) was significantly higher than baseline (46.4 ± 8.9) and remained significantly higher than baseline at 18 months (57.7 ± 10.6; both p < 0.001).
Conclusion
A weight management intervention using PCMs resulted in both clinically significant weight loss and increased diet quality scores, demonstrating that the use of PCMs during weight loss allows for meaningful changes in diet quality during weight maintenance.
Keywords: Portion Controlled Meals, Diet Quality, Weight Loss, Weight Maintenance, Diet
INTRODUCTION
The prevalence of overweight and obesity [body mass index (BMI) ≥ 25.0)] among US adults is ~68%, with 34% considered obese (BMI ≥ 30) 1. Overweight and obesity contribute to heart disease, hypertension, diabetes, and some cancers as well as psychosocial and economic issues 2. Evidence suggests that as little as 5–10% weight loss of initial body weight can improve obesity-related health complications 1,3,4. As a result, reduced-energy diets have become a major component of many weight loss programs 5,6.
Many individuals make repeated attempts to lose and maintain weight using a variety of diets and are unsuccessful. Portion controlled meals (PCMs) are often used in structured weight loss and maintenance programs. PCMs are any pre-portioned, packaged, low-calorie, high-nutritional content food intended to substitute for a “regular” meal prepared from raw ingredients. PCMs have consistently shown significantly greater weight loss and maintenance when compared to a conventional diet, as well as improvements in metabolic risk factors 7–10. Several studies suggest replacing as little as one meal per day with a PCM is associated with superior weight loss maintenance compared to programs utilizing conventional diet programs, such as calorie counting 7,8,10–12.
Despite strong evidence for the use of PCMs in weight loss and maintenance, there is a common public concern that those individuals who lose weight using PCMs do not develop an understanding of what constitutes “healthy eating” and do not develop the strategies and skills to maintain a healthy diet during weight maintenance. Thus, it is suggested that when PCMs are discontinued individuals will lack the ability to make proper healthy eating decisions. Previous studies suggest that consuming PCMs may improve diet quality during the period they are consumed11,13, but the long-term impact on diet quality of individuals following a weight loss intervention utilizing PCMs is unknown. Data from the (blinded for review) Equivalent Weight Loss for Phone & Clinic Weight Management Program (DK76063; acronym-Phone vs Clinic) afforded an opportunity to examine the effect of PCMs on diet quality during a weight loss and maintenance intervention that included PCMs, physical activity, and behavior education.
METHODS
A comprehensive description for Phone vs Clinic of the initial participant population, rationale, design, and methods has been previously published 14 as well as the primary outcome15. Briefly, Phone vs Clinic randomized overweight and obese individuals (BMI 25–44.9 kg·m2), living in the United States and aged 18–65 years, to a standardized weight management program delivered using either traditional face-to-face clinics or group conference calls (phone). The primary aim was to determine if weight loss at six months was equivalent for participants randomized to face-to-face clinic or group conference calls. This study was conducted according to the guidelines laid down in the Declaration of Helsinki, and all procedures involving human subjects were approved by the [name of the ethics committee removed for blinding]. Written informed consent was obtained from all subjects.
INTERVENTION
Educational sessions
Educational sessions for both groups were conducted weekly during the weight loss phase (month 0 to 6) and then gradually reduced during weight maintenance (months 7–18). Meetings were held twice per month during months 7–9, monthly during months 10–12, and every other month for the remainder of the 18 months. Both groups received the same education sessions. Weekly groups of 11–20 participants were led by health educators with backgrounds in nutrition, psychology, or exercise physiology and at least 1 year of experience in weight management. Meetings followed a standard protocol: review and discussion of self-reported data including minutes of physical activity, daily steps via step counter, and dietary compliance; a behaviorally-based lesson on a topic related to nutrition, physical activity and lifestyle modification; and group discussion, problem solving, and assignment of activities to assist participants in developing behavioral strategies associated with successful weight management.
Diet: weight loss (months 0–6)
Energy intake was reduced to ~5021 to 6278 kJ (1200 to 1500 kcal) per day using a combination of commercially available PCMs (Health Management Resources, Boston, MA) that were provided, for the first 6 months, free of cost as part of the study. Participants were instructed to consume a minimum daily total of 3 shakes [~418.4 kJ (100 kcal) each], 2 entrees [between 586 and 1130 kJ (140 and 270 kcal each)], and at least five 1-cup servings of fruits or vegetables. The entrées were ready-made meals that were shelf-stable and just needed to be heated up in a microwave for 1 minute. There were 12 entrée choices, which included beef stroganoff, mushroom risotto, cheese ravioli, turkey chili, and vegetable beef stew. All participants reported the number of shakes, entrées, fruits, and vegetables consumed each day to their health educator biweekly.
Diet: weight maintenance (7–18 months)
Participants were instructed to consume a weight maintenance diet with an energy level designed to maintain weight loss using the equation of Mifflin et al 16. Participants were given a meal plan based on their energy needs and the United States Department of Agriculture’s 2005 “My Pyramid” (www.mypyramid.gov) recommended servings of food groups. During weight maintenance, participants were encouraged but not required to continue consuming a minimum of 14 PCMs and 35 servings of fruits and vegetables per week.
Exercise
Participants were asked to complete 300 minutes per week of moderate to vigorous exercise during the 18-month trial. Exercise progressed from 45 minutes per week at intervention onset to the target of 300 minutes per week at the end of month 3 and remained at target for the final 12 months of the study.
ASSESSMENTS
All assessments were completed by trained research assistants at baseline, 6, 12, and 18 months.
Body weight, height, and BMI
Body weight was recorded using a digital scale accurate to ± 0.1 kg (Befour Inc Model #PS6600, Saukville, WI). All participants were weighed wearing a standard hospital gown, after attempting to empty their bowels, between the hours of 6:00am and 10:00am, and prior to breakfast. Height was measured using a stadiometer (Model PE-WM-60-84, Perspective Enterprises, Portage MI), and body mass index (kg/m2) was calculated.
Diet intake
Three-day food records were obtained to assess energy and macronutrient content of the diet. Participants were instructed to record all food and beverage consumption on 2 weekdays and 1 weekend day. Records were reviewed with the participants by a registered dietitian who used portion guides to help obtain accurate portion sizes. The portion guides used in the interviews were 3-dimensional models consisting of a variety of items intended to provide a reference and improve recall accuracy (i.e., glasses, mugs, bowls, circles, thickness sticks, chip bags, drink bottles, a 12-inch ruler, measuring cups and spoons, a grid, wedges, geometric shapes, and diagrams of chicken pieces)17. Records were removed from analysis if they did not represent a valid day (participant was very ill) or if the record could not be considered reliable (participant forgot 1 or more meals). The records were entered into the Nutrient Data System for Research (NDS-R; University of Minnesota, Minneapolis, MN; version 2011) for nutrient analysis.
Diet quality
The Healthy Eating Index-2010 (HEI-2010) was used to calculate diet quality from data obtained from the 3-day diet records at baseline, 6, 12, and 18 months. The HEI-2010 is a measure of diet quality developed by the United States Department of Agriculture that assesses conformance to the 2010 Dietary Guidelines for Americans 18. The HEI-2010 assesses the intake of total fruits, whole fruits, total vegetables, dark green vegetables and beans, refined grains, whole grains, milk, meats and beans, seafood and plant protein, fatty acid ratio, sodium, and empty calories. The HEI-2010 provides a point value based on how well a person meets the dietary guidelines expressed as a percent per 4184 kJ (1000 kcals) 19. The HEI-2010 was calculated using NDS-R output and a custom SAS code. Point values for each component were summed to give the final HEI score,. Higher component scores are indicative of better diet quality. The total maximum score for HEI-2010 is 100. Total fruits, whole fruits, total vegetables, greens and beans, total proteins, and seafood and plant protein all have a maximum score of 5 points. Whole grains, dairy, fatty acids, refined grains, and sodium have a maximum score of 10 points. Empty calories have a maximum score of 20 points. Higher component scores are generally indicative of higher consumption of those foods; however, the scoring for refined grains, sodium, and empty calories is inverted with higher scores being given to indicate lower consumption of those foods.
Physical activity
Physical activity was assessed by a portable accelerometer (Actigraph GT1M, Actigraph, LLC, Pensacola, FL). The GT1M is a small, lightweight, uni-axial, piezoelectric accelerometer, which measures and records vertical accelerations from approximately 0.05g to 2.0g with a frequency response from 0.25 to 2.50 Hz reflected as activity counts per minute (cts.min−1). Accelerometers were worn on an elastic belt over the non-dominant hip for 7 consecutive days. The data collection interval was set at one minute with a minimum of 10 hours constituting a valid monitored day. Three valid days were required to be included in the accelerometer analysis. Non-wear time was identified as ≥60 consecutive minutes with 0 cts.min−1, with allowance for 1–2 minutes of accelerometer counts between 0 and 100.. Data were downloaded using ActiGraph software and processed using a custom SAS program developed by our group. Sedentary time was defined as the time spent with accelerometer readings <100 cts.min−1, light (100–2019 cts.min−1), moderate (>3 METs, 2020–5999 cts.min−1) and vigorous PA (>6 METs, >5999 cts.min−1) 20.
Statistical analysis
Sample demographic characteristics were summarized by descriptive statistics and bivariate tests, such as independent-samples t-test, Chi-square, or Fisher’s exact test. All assessment variables were compared between males and females using independent-samples or Satterthwaite t-test at baseline, 6, 12, and 18 months. The correlations among changes in diet quality, weight, and physical activity were examined at each time point. Statistical significance was determined at 0.05 alpha level, and all analyses were performed using SAS Software, version 9.3 (SAS Institute Inc., Cary, NC).
RESULTS
Participants
Three hundred ninety-five individuals were randomized to one of the two study groups (phone or clinic). This analysis includes 197 participants who completed the 18-month study and provided valid and reliable 3-day food records for calculation of HEI-2010 at all four of the time points.. Baseline participant characteristics are presented in Table 1. There were no significant differences in baseline characteristics between the 197 participants included in this analysis and the 395 participants randomized at baseline.
Table 1.
Baseline participant characteristics for the complete sample and by gender.
| Variable | Complete Sample (n=197) | Men (n=65) | Women (n=132) |
|---|---|---|---|
| Age (yrs.) | 46.1 (8.9) | 45.1 (9.1) | 46.6 (8.8) |
| Height (cm) | 169.8 (9.1) | 178.8(6.1) | 165.3 (6.7) |
| Weight (kg) | 98.6 (17.2) | 111.0 (15.7) | 92.5 (14.5) |
| BMI (kg · m−2) | 34.1 (4.5) | 34.6 (4.1) | 33.8 (4.6) |
| Minority (%) | 16.8% | 15.4% | 17.4% |
Note. BMI = body mass index. Values are mean (SD) unless otherwise stated. Height and weight were significantly different between men and women (both p < 0.001), but there were no significant differences in age, BMI, and ethnicity (minority).
PCM consumption and attendance
Participants consumed an average of 12.1± 1.4 entrees and 18.1± 2.5 shakes per week during the weight loss phase, which is less than the 14 entrees and 21 shakes they were instructed to consume during weight loss. However, they consumed more than the 35 fruits and vegetables as instructed (mean 40.7± 8.6). During weight maintenance, although not required, participants continued to consume an average of ~ 9 PCMs per week and 36.5± 10.5 fruits and vegetables per week during months 7–12 and 34.4± 9.8 per week during months 13–18. Full PCM consumption data is shown in Table 2. Attendance at behavioral sessions averaged 88% during weight loss and 76% during weight maintenance.
Table 2.
Self-Reported Consumption of Portion Controlled Meals, Physical Activity Minutes, and Attendance at Education Sessions during an 18 month Behavioral Weight Loss Program.
| Variable | Complete Sample (n=197) | Men (n=65) | Women (n=132) | p for sex difference |
|---|---|---|---|---|
| Entrees (number/wk) | ||||
| Months 0–6 | 12.1 (1.4) | 12.3 (1.3) | 12.1 (1.5) | 0.241 |
| Months 7–12 | 5.3 (3.7) | 4.6 (3.7) | 5.6 (3.6) | 0.058 |
| Months 13–18 | 3.9 (3.8) | 3.1 (3.9) | 4.3 (3.8) | 0.062 |
| Shakes (number/wk) | ||||
| Months 0–6 | 18.1 (2.5) | 18.3 (2.7) | 18.1 (2.4) | 0.584 |
| Months 7–12 | 5.6 (4.4) | 5.0 (4.1) | 5.8 (4.6) | 0.232 |
| Months 13–18 | 2.9 (4.3) | 1.9 (3.4) | 3.5 (4.6) | 0.011 |
| Fruits/Vegetables (number/wk) | ||||
| Months 0–6 | 40.7 (8.6) | 44.8 (10.2) | 38.6 (6.9) | <0.001 |
| Months 7–12 | 36.5 (10.5) | 40.4 (11.5) | 34.5 (9.3) | 0.001 |
| Months 13–18 | 34.3 (9.8) | 37.7 (11.6) | 32.5 (8.1) | 0.003 |
| Education sessions (%attended) | ||||
| Months 0–6 | 88 (9)% | 88 (9)% | 88 (9)% | 0.922 |
| Months 7–12 | 76 (22)% | 75 (25) % | 77 (20)% | 0.566 |
| Months 13–18 | 76 (31)% | 74 (31)% | 77 (32)% | 0.611 |
| Moderate-to-vigorous physical activity (min/day) | ||||
| Month 0 | 16.9 (14.5) | 23.8 (18.6) | 13.5 (10.7) | 0.002 |
| Month 6 | 35.9 (22.4) | 44.9 (27.2) | 31.5 (18.3) | 0.014 |
| Month 12 | 28.2 (20.1) | 32.4 (21.9) | 26.1 (19.1) | 0.201 |
| Month 18 | 30.5 (22.2) | 37.8 (25.8) | 26.6 (19.2) | 0.037 |
Note. Values are mean (SD) unless otherwise stated.
Diet quality
Total HEI-2010 scores significantly improved by 20.3±11.9 (p<0.001) during weight loss (baseline= 46.6±8.9; month 6= 66.6± 9.4) and remained above baseline during weight maintenance (12 months=58.0±10.1; 18 months= 57.7±10.6; both p<0.001). Men had significantly lower baseline HEI-2010 scores than women did at baseline (p<0.001), month 6 (p=0.001), and month 12 (p=0.017), but men also had a significantly greater change in HEI-2010 scores across time from baseline to month 18 (p=0.013). Total HEI-2010 scores for the complete sample, men, and women are shown in Table 3. An increase in HEI-2010 total score was significantly associated with a greater percent weight loss at months 6, 12, and 18 (all p <0.001). HEI components that significantly improved across the study were servings of whole fruits, total vegetables, refined grains, fatty acid intake, and empty calories. HEI-2010 component scores across the 18-month study are found in table 4.
Table 3.
Diet quality as assessed by the Healthy Eating Index-2010 (HEI) across 18 months in the complete sample, men, and women
| Variable | Complete Sample (n=197) | Men (n=65) | Women (n=132) | p for sex difference |
|---|---|---|---|---|
| Total HEI score | ||||
| Month 0 | 46.4 (8.9) | 42.2 (9.0) | 48.4 (8.1) | <0.001 |
| Month 6 | 66.6 (9.4) | 63.6 (9.5) | 68.1 (9.0) | 0.001 |
| Month 12 | 58.0 (10.1) | 55.5 (10.4) | 59.2 (9.8) | 0.017 |
| Month 18 | 57.7 (10.6) | 56.5 (9.9) | 58.3 (10.8) | 0.255 |
| Total HEI score change | ||||
| Months 0–6 | 20.3 (11.9) | 21.4 (12.5) | 19.7 (11.6) | 0.338 |
| p for change | <0.001 | <0.001 | <0.001 | |
| Months 6–12 | −8.6 (10.3) | −8.1 (11.1) | −8.9 (10.0) | 0.573 |
| p for change | <0.001 | <0.001 | <0.001 | |
| Months 12–18 | −0.3 (10.8) | 0.9 (10.2) | −0.9 (11.0) | 0.263 |
| p for change | 0.679 | 0.474 | 0.338 | |
| Months 0–18 | 11.3 (11.9) | 14.3 (12.1) | 9.8 (11.6) | 0.013 |
| p for change | <0.001 | <0.001 | <0.001 | |
| Months 6–18 | −9.0 (11.2) | −7.1 (11.5) | −9.9 (10.9) | 0.108 |
| p for change | <0.001 | <0.001 | <0.001 | |
Note. Values are mean (SD) unless otherwise stated.
Table 4.
Healthy Eating Index-2010 (HEI) component scores across 18 months in the complete sample, men, and women
| Variable | Complete Sample (n=197) | Men (n=65) | Women (n=132) |
|---|---|---|---|
| Total fruits* | |||
| 0 month | 1.26 (1.33) | 0.95 (1.21) | 1.42 (1.37) |
| 6 months | 4.13 (1.29) | 3.96 (1.41) | 4.21 (1.23) |
| 12 months | 3.14 (1.59) | 3.07 (1.58) | 3.17 (1.60) |
| 18 months | 3.08 (1.64) | 3.22 (1.65) | 3.02 (1.64) |
| Whole fruits* | |||
| 0 month | 1.59 (1.49) | 1.12 (1.40) | 1.83 (1.48) |
| 6 months | 4.46 (1.14) | 4.32 (1.27) | 4.53 (1.06) |
| 12 months | 3.76 (1.53) | 3.70 (1.55) | 3.79 (1.53) |
| 18 months | 3.64 (1.61) | 3.71 (1.47) | 3.60 (1.68) |
| Total vegetables* | |||
| 0 month | 2.63 (1.17) | 2.42 (1.20) | 2.73 (1.14) |
| 6 months | 4.59 (0.79) | 4.55 (0.75) | 4.60 (0.81) |
| 12 months | 3.88 (1.19) | 3.83 (1.33) | 3.91 (1.11) |
| 18 months | 3.68 (1.14) | 3.68 (1.07) | 3.68 (1.17) |
| Dark green & Orange Vegetables * | |||
| 0 month | 1.32 (1.22) | 1.00 (1.10) | 1.47 (1.25) |
| 6 months | 3.41 (1.52) | 2.89 (1.71) | 3.66 (1.36) |
| 12 months | 2.55 (1.65) | 2.24 (1.77) | 2.70 (1.57) |
| 18 months | 2.23 (1.57) | 2.19 (1.68) | 2.25 (1.52) |
| Refined grains** | |||
| 0 month | 4.76 (2.60) | 4.98 (2.67) | 4.65 (2.56) |
| 6 months | 8.14 (2.07) | 8.17 (2.19) | 8.12 (2.02) |
| 12 months | 5.46 (2.88) | 5.64 (2.67) | 5.37 (2.98) |
| 18 months | 5.42 (2.92) | 6.26 (2.69) | 5.01 (2.94) |
| Whole grains** | |||
| 0 month | 3.69 (2.82) | 3.28 (2.63) | 3.89 (2.89) |
| 6 months | 1.93 (2.33) | 2.18 (2.40) | 1.80 (2.29) |
| 12 months | 3.60 (2.91) | 3.13 (2.86) | 3.83 (2.93) |
| 18 months | 3.65 (3.07) | 3.11 (2.70) | 3.92 (3.21) |
| Milk** | |||
| 0 month | 5.99 (2.75) | 4.57 (2.79) | 6.69 (2.45) |
| 6 months | 6.76 (3.24) | 5.41 (3.20) | 7.43 (3.05) |
| 12 months | 5.98 (2.97) | 4.63 (2.81) | 6.65 (2.83) |
| 18 months | 5.86 (3.00) | 4.70 (3.33) | 6.44 (2.64) |
| Total protein* | |||
| 0 month | 4.07 (0.95) | 4.23 (0.85) | 4.00 (1.00) |
| 6 months | 4.41 (0.79) | 4.48 (0.68) | 4.37 (0.84) |
| 12 months | 4.09 (0.99) | 4.02 (0.97) | 4.12 (1.01) |
| 18 months | 4.12 (1.03) | 4.07 (1.12) | 4.14 (0.99) |
| Seafood and Plant Protein* | |||
| 0 month | 3.51 (1.35) | 2.79 (1.50) | 3.86 (1.12) |
| 6 months | 3.75 (1.51) | 3.11 (1.61) | 4.06 (1.36) |
| 12 months | 3.47 (1.50) | 2.77 (1.55) | 3.81 (1.36) |
| 18 months | 3.48 (1.52 | 2.84 (1.77) | 3.80 (1.27) |
| Fatty acid ratio** | |||
| 0 month | 4.86 (2.41) | 4.70 (2.23) | 4.94 (2.49) |
| 6 months | 5.54 (2.45) | 5.47 (2.21) | 5.58 (2.57) |
| 12 months | 5.56 (2.47) | 5.81 (2.38) | 5.44 (2.52) |
| 18 months | 5.71 (2.53) | 5.23 (2.28) | 5.95 (2.62) |
| Sodium** | |||
| 0 month | 3.54 (2.48) | 3.27 (2.72) | 3.67 (2.36) |
| 6 months | 2.45 (2.24) | 2.05 (2.14) | 2.64 (2.27) |
| 12 months | 2.63 (2.40) | 2.56 (2.38) | 2.66 (2.42) |
| 18 months | 2.89 (2.39 | 2.66 (2.35) | 3.00 (2.41) |
| Empty Calories*** | |||
| 0 month | 9.14 (4.25) | 8.85 (4.21) | 9.28 (4.27) |
| 6 months | 17.09 (3.48) | 17.00 (3.34) | 17.13 (3.56) |
| 12 months | 13.89 (4.49) | 14.15 (4.19) | 13.75 (4.64) |
| 18 months | 13.91 (4.68) | 14.80 (4.22) | 13.47 (4.84) |
Note. Values are mean (SD) unless otherwise stated.
Maximum point value is 5
Maximum point value is 10
Maximum point value is 20
Weight changes
A detailed description of weight change in this trial has been published 15. Weight loss in 197 participants included in this analysis was −14.3 ± 6.6% and −8.7 ± 8.0% at 6 and 18 months, respectively (both p < 0.001). Weight change was similar in men and women. In men, weight loss was −15.4 ± 6.3% at 6 months and −9.1 ± 7.7% at 18 months; in women, weight loss was −13.8 ± 6.7% at 6 months and −8.5 ± 8.2% at 18 months (all p < 0.001).
Physical activity
During weight loss, moderate to vigorous physical activity (MVPA) minutes increased from 16.9 ± 14.5 to 35.9 ±22.4 minutes per day. MVPA decreased slightly to 28.2 ±20.1 minutes at month 12 and 20.4± 22.2 minutes at month 18. Men had significantly greater minutes of MVPA than women at baseline, month 6, and month 18. Multivariate correlation analysis was performed between changes in HEI total scores, percent weight loss, sedentary activity (min·d−1), light activity (min·d−1), and MVPA (min·d−1). In the overall sample, a greater increase in percent weight loss was significantly associated with MVPA (p < 0.01) at 0–6, 0–12, and 0–18 months with a correlation of r2 = −0.32. There was no significant correlation between MVPA and diet quality.
DISCUSSION
The specific aim of this analysis was to determine the impact of PCMs, combined with behavior education and exercise, on diet quality during weight loss and weight maintenance. The effect of a diet on diet quality is important as poor diet quality has been found to be associated with inflammation, insulin resistance, and some cancers 21–23. Improvements in diet quality may reduce the risk of these conditions separate from benefits seen with weight loss. However, the use of PCMs in overweight and obese individuals for weight loss raises concern that these products might not foster healthy food choices during weight maintenance. The results found that HEI-2010 scores at baseline were below the average HEI-2010 score of 53.5 reported for US adults 24 and that diet quality increased significantly following a 6-month weight loss program where PCM consumption was required.
These results are in general agreement with those from the available literature 8,13,25,26. For example, Ashley et. al. 13 compared macronutrient and micronutrient levels in foods chosen by 96 women, ages 25–30 years, that were randomized into either a traditional diet group or PCM group, reported that those who were in the PCM group decreased intake of saturated fat, cholesterol, and sodium, with increased total fruits and vegetables. Additionally, those who used PCMs had significantly lower risk for inadequate intake of vitamins and minerals compared to traditional diet group. Noakes et. al. 25 and Miller et. al. 26 both found no difference in intake in any macronutrients or in micronutrients, including magnesium, calcium, iron, and zinc, in those consuming PCMs. Additionally Noaks et al. 25 found that food choice and meal pattern resulted in similar energy distributions of protein and carbohydrate intakes and relatively low fat intake in those using PCMs compared to traditional diet. In addition, Ditschuneit et al. 27 reported a significant (p<0.05) decrease in total fat intake in both men and women using PCMs.
We are unaware of reports in the literature examining the impact of a PCM weight loss diet on diet quality during weight maintenance. Thus, we expanded on these findings and looked at the changes in diet quality after PCMs were no longer required to determine the effect of PCMs for weight loss on diet quality during 12 months of weight maintenance. Interestingly, diet quality remained significantly higher than baseline during weight maintenance even as the consumption of PCMs decreased to ~5 entrees and ~ 4 shakes per wk. HEI-2010 score during weight maintenance was 57.9, which is higher than the average for US adults 24. HEI-2010 components that improved significantly across the study were servings of whole fruits, total vegetables, refined grains, fatty acid intake, and empty calories. Results demonstrated that individuals increased their fruit and vegetables servings and decreased their intake of saturated fat, refined gains, and foods with added fat and sugar.
PCMs are often critiqued for being high in sodium. However, we found sodium scores did not change significantly from baseline. These results are in agreement with those of Ashley et al 13 who found sodium intake being reduced and were close to recommended values in those consuming PCMs. The observation that sodium intake is reduced or unchanged suggests that PCMs may not add significantly more sodium to an individual’s diet.
It can be argued that the increased diet quality was driven by the increased consumption of fruits and vegetables during weight loss and their continued increased consumption during weight maintenance. However, there was an increase in other components of diet quality besides fruits and vegetables; most notably, there were a decreased intake of refined grains and empty calories and improved fatty acid ratio scores. Interestingly, physical activity and attendance at the educational sessions were not correlated with diet quality scores. These findings suggest that, while the behavior clinic helped individuals develop healthy lifestyle patterns, the PCMs may play a significant role in the increased diet quality over behavior clinic alone.
Strengths of the current study include the use of a randomized design trial with a weight management intervention over 18-months that delivered the same behavioral education to all participants, a large sample, the inclusion of both males and females, and a rigorous assessment of diet quality during both weight loss and weight maintenance. However, while the results are encouraging, this study should be considered in the context of certain limitations. First, Phone vs Clinic was not specifically designed or powered to detect between or within group differences in change of HEI-2010 scores in response to PCMs. Secondly, there is no comparison group to see if the same changes in HEI-2010 scores are obtained using traditional, reduced-energy meal plan diets. Finally, dietary intake was collected by self-reported diet records, which can be biased by social desirability or social approval 28 and have been shown to underestimate EI when compared with energy expenditure assessed by doubly labeled water 29–33.
Previous research has shown that PCMs produce significant weight loss compared to a standard diet, provide a nutritionally adequate diet, and may increase fruit and vegetable consumption. Yet, there is doubt that individuals who lose weight by using PCMs develop an understanding of healthy eating during weight maintenance. Although we have no comparison of changes in diet quality using a traditional reduced energy meal plan diet, our results do not support the notion that weight loss using PCM diets are ineffective for either long-term maintenance of weight loss or result in poor long-term diet quality. Furthermore, PCMs during weight loss may actually help to improve the diet quality of individuals even during weight maintenance.
Acknowledgments
This study was supported by the National Institutes of Health grant R01- DK049181 and Health Management Resources, Boston MA
Footnotes
Authorship: LP, DS, JD designed the study, JG, DS, and JD collected the data, LP, ASR, JL analyzed the data, JL did the statistical analysis, LP, EW, JG drafted the paper, all authors reviewed its content and approved the final version.
Conflict of Interest: All authors report no conflicts of interest.
Contributor Information
Erik A. Willis, Email: ewillis@ku.edu.
Jeannine R. Goetz, Email: jgoetz@kumc.edu.
Jaehoon Lee, Email: jaehoon.lee@ttu.edu.
Amanda N. Szabo-Reed, Email: aszabo@ku.edu.
Debra K. Sullivan, Email: dsulliva@kumc.edu.
Joseph E. Donnelly, Email: jdonnelly@ku.edu.
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