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Keywords:

  • weight loss;
  • risk factors;
  • primary care practice;
  • nutrients;
  • premenopausal women

Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Research Methods and Procedures
  5. Results
  6. Discussion
  7. Acknowledgments
  8. References

Objective: To evaluate the effectiveness of meal replacements (MRs) in weight loss interventions in premenopausal women.

Research Methods and Procedures: Overweight premenopausal women (n = 113; body mass index: 25 to 35 kg/m2; 30 to 50 years old) were randomized into three interventions: group A, a dietitian-led intervention; group B, a dietitian-led intervention incorporating MRs; and group C, a clinical office-based intervention incorporating MRs. In year 1, groups A and B attended 26 group sessions, whereas group C received the same educational materials during 26 10-minute office visits with a physician–nurse team. In year 2, participants attended monthly group seminars and drop-in visits with a dietitian.

Results: For the 74 subjects completing year 1, weight loss in the office-based group C was as effective as the traditional dietitian-led group A (4.3 ± 6.5% vs. 4.1 ± 6.4%), while group B maintained a significantly greater weight loss (9.1 ± 8.9%; p < 0.02; mean ± SD). For the 43 subjects completing year 2, group B showed significant differences in the percentage of weight loss (−8.5 ± 7.0%) compared with group A (−1.5 ± 5.0%) and group C (−3.0 ± 7.0%; p < 0.001).

Discussion: Study results showed that a traditional weight loss intervention incorporating MRs was effective as a weight loss tool in the medical office practice and in the dietitian-led group setting.


Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Research Methods and Procedures
  5. Results
  6. Discussion
  7. Acknowledgments
  8. References

Obesity is now defined as a progressive and relapsing chronic disease that is linked to many common diseases, including cardiovascular disease, type 2 diabetes, hypertension, stroke, osteoarthritis, respiratory problems, and certain cancers (1) (2) (3). An estimated 97 million Americans, or >50% of the adult population, are currently classified as overweight or obese. As the rate of overweight and obesity continues to increase, the associated comorbidities will continue to rise as well. This is reflected in rising economic costs, with the direct cost of obesity estimated to be nearly 6% of our national health expenditure (4).

Insurance companies that promoted evaluations of height and weight in the early 1920s (5) have recognized the important role of weight in health and longevity for over 75 years. However, the prevention and treatment of overweight and obesity continues to be poorly reimbursed and underestimated. In addition, although physicians are in an excellent position to identify and intervene with patients who are at risk, their involvement in the treatment of obesity has been limited (6). To encourage health professionals to take a more active role as agents of change in the obesity management of their patients, effective and practical lifestyle intervention options that can be delivered in a busy clinical setting are needed (7) (8) (9). Recent reports indicate that meal replacements (MRs) coupled with a low-calorie diet can offer an effective option for long-term compliance or improvements in metabolic risk factors in patients who visit a clinic (10) (11) (12) (13) (14). These studies examined a MR intervention in a university-based clinic, community-based intervention program, or minimal clinic intervention. We previously reported on the first randomized, controlled trial over a 1-year period to compare the use of MR in an established university-based weight loss clinic and a primary care physician practice (10). This study extends these results to 2 years of observations.

This 2-year randomized study was designed to address two main questions regarding diet and weight loss in overweight and moderately obese women. First, can primary care physicians implement successful long-term lifestyle changes using MRs despite their limited clinical time to discuss complex issues of weight management with their patients? Second, can a traditional lifestyle modification program delivered by the registered dietitian using a MR strategy be as effective as the same program using a standard food plan strategy? An additional goal of this study was to evaluate how this approach in overweight and moderately obese women affects specific chronic disease risk factors and diet adequacy.

Research Methods and Procedures

  1. Top of page
  2. Abstract
  3. Introduction
  4. Research Methods and Procedures
  5. Results
  6. Discussion
  7. Acknowledgments
  8. References

Participants

Overweight or moderately obese premenopausal women with a body mass index (BMI) between 25 and 35 kg/m2, 25 to 50 years old, were selected from those responding to media announcements and flyers distributed in the local metropolitan area. After being screened by telephone questionnaire, interested women attended a group orientation meeting, where details of the study were explained before written consent was obtained. Exclusion criteria included current chronic medical or psychological disease, abnormal serum laboratory values of clinical significance, or current hormone replacement therapy. Women were also excluded if they were pregnant, lactating, or planning to become pregnant. Those still qualified after this initial screening participated in an additional assessment to determine their fasting serum chemistry, lipid, insulin, and glucose values; weight, height, BMI, waist circumference, body fat percentage, resting energy expenditure (REE; kcal per 24 hours), blood pressure, dieting histories, eating and activity habits, and psychosocial status. A medical release from a physician was required to participate in the study. There were no costs to participants for assessment measures, lifestyle modification materials or consultations (whether provided in the physician's office or in groups), or MR products. The University of Nevada Human Subjects Committee approved all procedures used in this study.

Lifestyle Intervention

In the first year of the study, participants were randomly assigned to one of three interventions, as described in detail below. All participants attended a total of 26 sessions and received instruction manuals that included lessons based on the LEARN Program for Weight Control (15), with enhancements in nutrition and physical activity developed in our university program. At each session, 1 of the 26 intervention lessons from the instruction manual was distributed to participants. Diet instruction included a low-calorie diet of ∼1200 kcal/d (with no >30% of calories from fat), based on the U.S. Department of Agriculture Food Guide Pyramid. Physical activity instruction included a recommendation to increase energy expenditure by walking up to 10,000 steps per day as measured by a pedometer (Yamax Digi-Walker, San Jose, CA) that was supplied to each participant. Participants completed homework assignments that included self-monitoring by recording food intake and physical activity choices. In the maintenance phase of the study conducted in the second year, all three groups attended scheduled monthly seminars together. They also had individual unscheduled monthly drop-in visits at the university study center. Diet instruction remained the same for the three groups, with one group following a traditional intervention and the two other groups following a traditional intervention that continued to incorporate MR.

Group A: Traditional Dietitian Intervention Group

In the first year of the study, participants in group A attended a series of small group classes (8 to 10 participants per class) led by a registered dietitian. A total of 26 one-hour sessions were held: weekly for the first 3 months (introduction and 12 sessions), biweekly for the second 3 months (6 sessions), and monthly for the final 6 months (6 sessions and a session at 1 year). The diet consisted of all meals and snacks prepared from self-selected conventional foods.

In the maintenance phase of the study conducted in the second year, women in group A continued to follow the traditional intervention, with no MRs. However, they attended monthly dietitian-led seminars that were held for all groups. Topics at these sessions were based on the maintenance phase of the LEARN manual. Participants also had individual unscheduled monthly drop-in visits for measuring weight and for picking up supplemental weight maintenance material handouts at the university study center during usual weekday work hours.

Group B: Traditional Dietitian Intervention Group Incorporating MR

In the first year of the study, similar to group A, participants in this intervention also attended small group classes led by a registered dietitian, including the 26 sessions held on the same weekly, biweekly, and monthly schedule. This group received similar self-selected diets, except that two of the three main meals (breakfast, lunch, or dinner) were replaced with MR shakes or MR bars (Slim-Fast; Slim-Fast Foods Co., West Palm Beach, FL). Each liquid MR shake contained 220 kcal, 7 to 10 g of protein, 40 to 46 g of carbohydrate of which 5 g was dietary fiber, 1.5 to 3 g of fat, and was supplemented with 15% to 100% of the percentage daily value for essential vitamins and minerals. Each MR bar contained 220 kcal, 8 g of protein, 33 to 36 g of carbohydrate, 5 g of fat, and 2 g of dietary fiber and was supplemented with 25% to 35% of the percentage daily value for essential vitamins and minerals. The MR shakes were supplied through coupons that the participants redeemed at local stores, and the MR bars were distributed at scheduled group sessions.

In the maintenance phase of the study conducted in the second year, women in group B continued to follow their traditional intervention with MR incorporated into their program. They attended monthly dietitian-led seminars that were held for all groups. Participants also had individual monthly university contact visits for measuring weight and for picking up supplemental weight maintenance material handouts. They also picked up their MR coupons or MRs at these drop-in visits.

Group C: Physician–Nurse Group Incorporating MR

In the first year of the study, participants in this intervention group met every 2 weeks with a primary care physician (two-thirds of the time) or a nurse (one-third of the time) during scheduled visits in the outpatient medical practice clinic of the university. These biweekly visits (26 sessions) lasted from 10 to 15 minutes, and the total number of sessions was the same as for groups A and B. The diet prescription in this group was identical to that of group B, using self-selected diets with MR shakes and bars. During the structured physician or nurse visits, the progress of each subject was reviewed, including diet, behavior modification, and physical activity habits. Any brief questions about the instruction manual lessons were addressed. These participants received no additional counseling during the year.

In the maintenance phase of the study conducted in the second year, women in group C continued to follow their traditional intervention with MR incorporated into their program. They did not continue their brief clinic visits, but they attended the monthly dietitian-led seminars that were held for all groups. Participants also had individual monthly university contact visits for measuring weight and for picking up supplemental weight maintenance material handouts. They picked up their MR coupons or MRs at these drop-in visits, as did group B.

Women in the MR groups (groups B and C) who lost 10% of their initial body weight were instructed to replace only one of three main meals each day with a MR shake or bar. If these subjects regained weight, then they were instructed to reinitiate the use of two MRs until they lost the weight.

Dependent Measures

Milestone measures were taken at baseline, 1 year, and 2 years and included weight, height, waist circumference and body composition (bioelectrical impedance), REE, and blood pressure. Certified technicians took blood pressure and body composition measurements. Fasting blood was taken for measuring serum lipids (total cholesterol, low-density lipoprotein [LDL] cholesterol, high-density lipoprotein [HDL] cholesterol, and triglycerides), glucose, and insulin by a certified phlebotomist. Blood values were analyzed by standard methods at a statewide, certified clinical laboratory. Weight measurements (nearest 0.10 kg) were taken using the same calibrated balance beam scale with patients dressed in light clothing without shoes. Height measurements (nearest 0.5 cm) were taken using a mounted wall stadiometer, and BMI (kg/m2) was calculated. Waist circumference was measured at the narrowest point of the torso (nearest 0.1 cm) using a nonstretchable tape measure. Bioelectrical impedance (Xitron, San Diego, CA) was used to calculate the percentage of body fat. Twenty-four-hour REE (kcal) was estimated from a 20-minute respiratory sample in fasting participants using a ventilated canopy hood by indirect calorimetry (16) (Sensor Medics, Anaheim, CA) in year 1 and was estimated from a prediction equation in year 2 (S.T.S.J, unpublished data). Blood pressure was measured on the right arm using a mercury column manometer (nearest mm Hg) after the fasting subject had been seated quietly for 5 minutes. Nutrient analysis was performed using 3-day food records with the Minnesota Nutrient Data System Research version. Servings of fruits and vegetables were calculated directly from the 3-day food records.

Statistics

All data are presented as means ± SD except for the nutrient data, which are presented as the means ± SEM. The primary dependent variable, weight change, and all other analyses comparing across the three groups were examined by a one-way ANOVA with subsequent a priori analyses using contrasts for completers. When the examination focused on only one group (within analyses), a paired sample t test was used. The statistical package SPSS, version 9 (SPSS, Chicago, IL) was used to analyze the data for statistical significance.

Results

  1. Top of page
  2. Abstract
  3. Introduction
  4. Research Methods and Procedures
  5. Results
  6. Discussion
  7. Acknowledgments
  8. References

Weight and Risk Factor Comparisons by Intervention Groups

Participants Completing Both the 1-Year and 2-Year Study Time-Point Assessments.

Of the 113 initial women who met the inclusion criteria and agreed to be randomly assigned to study groups, 74 participants completed all assessments for the first year of study, and 39 participants completed all assessments for the second year of the study.

Participants Completing the 1-Year Time-Point Assessments.

Baseline characteristics of the 74 participants completing the first year of the study are shown as mean (SD) in Table 1. There were no significant differences among the baseline parameters by treatment group. Weight change and the percentage of weight lost for the participants who completed the 1-year study assessments are shown in Table 2. Group B (n = 26) lost significantly more weight than did group A (n = 23; p ≤ 0.02) and group C (n = 25; p ≤ 0.02) at 1 year. Group B showed a mean loss of 7.7 (7.8) kg or 9.1% (8.9%) of initial body weight, whereas groups A and C lost 3.4 (5.4) kg or 4.1% (6.4%) and 3.5 (5.5) kg or 4.3% (6.5%), respectively.Table 2 also shows that there was a significant decrease in BMI (kg/m2) in group B compared with group A (p ≤ 0.02).

Table 1.  Baseline characteristics of groups and total sample at 1 year
VariableGroup A (n = 23)Group B (n = 26)Group C (n = 25)All groups (n = 74)
  1. No significant differences in baseline values among the threegroups.

  2. Mean (SD).

Age (years)42.3 (4.1)41.0 (4.3)41.0 (5.7)41.4 (4.7)
Weight (kg)82.9 (9.1)83.5 (9.5)83.2 (11.0)83.2 (9.8)
BMI (kg/m2)29.9 (2.6)30.1 (2.9)30.1 (3.7)30.0 (3.1)
Body fat (%)38.4 (5.2)38.4 (3.9)36.7 (5.4)37.8 (4.9)
Waist circumference (cm)93.7 (8.0)93.7 (8.3)92.8 (9.6)93.4 (8.6)
REE (kcal/24 hours)1561 (153)1586 (193)1608 (267)1586 (209)
Systolic blood pressure (mm Hg)124 (12)123 (17)117 (12)121 (14)
Diastolic blood pressure (mm Hg)70 (8)71 (10)70 (10)70 (9)
Glucose (mM)4.9 (0.4)4.9 (0.5)4.6 (0.4)4.8 (0.4)
Insulin (pM)14.8 (10.8)11.9 (6.9)11.7 (4.9)12.7 (7.8)
Cholesterol (mM)4.9 (0.9)5.4 (0.8)5.3 (1.1)5.2 (1.0)
Triglycerides (mM)1.35 (0.6)1.5 (0.8)1.4 (0.7)1.4 (0.7)
HDL cholesterol (mM)1.4 (0.3)1.5 (0.4)1.4 (0.3)1.4 (0.3)
LDL cholesterol (mM)2.9 (0.9)3.3 (0.7)3.3 (0.9)3.2 (0.8)
Table 2.  Group changes in weight and anthropometrics at 1 year (N = 74)
VariableGroup A (n = 23)Group B (n = 26)Group C (n = 25)
  • Mean (SD).

  • *

    p ≤ 0.05 comparison between A vs. B and B vs. C.

Actual weight change (kg)−3.4 (5.4)−7.7 (7.8)*−3.5 (5.5)
Percentage weight lost from baseline (%)−4.1 (6.4)−9.1 (8.9)*−4.3 (6.5)
BMI (kg/m2)−1.0 (2.0)−2.5 (2.7)*−1.3 (2.0)
Participants Completing Both the 1- and 2-Year Time-Point Assessments.

Baseline characteristics along with significant (p ≤ 0.05) changes at 1 year and 2 years for the 39 participants completing all time-point measurements of the study are shown in Table 3. There were no significant differences among the baseline parameters by treatment group. Members of group B (n = 16) lost significantly more weight than did members of group A (n = 11) or group C (n = 12) at 2 years. Within-group analysis compared with baseline showed a significant difference for group A in weight (year 1), BMI (year 1), waist circumference (years 1 and 2), REE (year 1), and HDL cholesterol (year 2). Similar analysis showed a significant difference for group B in weight (years 1 and 2), percentage of body fat (years 1 and 2), BMI (years 1 and 2), waist circumference (years 1 and 2), REE (years 1 and 2), and blood cholesterol (year 1). For group C, a similar within-group analysis showed a significant difference for weight (year 1), BMI (year 1), percentage of body fat (years 1 and 2), waist circumference (years 1 and 2), REE (years 1 and 2), systolic blood pressure (year 2), and blood LDL cholesterol (year 2).

Table 3.  Group variable changes comparing baseline, year 1, and year 2 (N = 39)*
 Group A (n = 11)Group B (n = 16)Group C (n = 12)
VariableBaselineChange year 01 to baselineChange year 02 to baselineBaselineChange year 01 to baselineChange year 02 to baselineBaselineChange year 01 to baselineChange year 02 to baseline
  • *

    No significant difference in baseline values among the three groups.

  • Mean (SD), significant difference p ≤ 0.05.

  • Difference between groups assumes equal variances.

  • Significant difference among all groups at year 01.

  • Significant difference between groups A and B at year 02.

  • §

    Significant difference between groups B and C at year 02.

  • Significant difference between groups A and C at year 02.

  • **

    Significant difference within group A, group B, or group C at year 01 or year 02.

Age (years)44 (4)42 (4)42 (4)
Weight (lb)181.0 (26.1)−8.6 (10.6) **−3.6 (9.4)185.4 (22.7)−21.3 (15.4) **−16.8 (14.9) § **187.8 (28.2)−7.4 (14.4)−7.1 (15.6)
Weight (kg)−82.2 (11.9)−3.9 (4.8)−1.6 (4.3)−84.3 (10.3)−9.7 (7.0)−7.6 (6.8)85.4 (12.8)3.4 (6.5)3.2 (7.1)
Weight loss (%)−4.8−2.0−11.5−9.1−3.9−3.8
Body fat (%)36.7 (5.0)−2.6 (5.4)−2.2 (4.4)38.2 (4.9)−5.9 (4.9)**−5.1 (4.7)**37.3 (5.2)−2.9 (4.6)**−2.9 (4.2)**
BMI29.7 (2.9)−1.2 (1.7) **+0.4 (3.9)30.4 (3.2)−3.0 (2.3) **−2.6 (2.4)§ **30.6 (4.2)+1.0 (2.4)−0.9 (2.0)
Waist circumference (cm)90.9 (7.1)−4.7 (5.1)**−5.9 (3.8)**92.6 (7.9)−8.5 (7.7)**−8.6 (6.8)**95.3 (11.0)−5.3 (5.9)**−6.8 (7.5)**
REE (kcal/d)1561 (187)−105 (147)**−57 (178)1604 (193)−207 (141)**−147 (164)**1648 (303)−98 (100)**−143 (216)**
Systolic blood pressure124 (14)−5 (11)−3 (9)125 (15)−5 (16)−4 (14)115 (12)+2.3 (12.4)+13 (15)**
Diastolic blood pressure72 (8)−4 (9)−3 (6)71.0 (11.2)−2 (8)−3 (9)67 (12)−1 (8)+1 (8)
Glucose (mg/dL)4.9 (.47)+0.2 (0.5)+0.2 (0.6)4.9 (0.5)−0.1 (0.4)+0.7 (0.2)4.7 (0.3)+0.1 (0.3)+0.2 (0.5)
Insulin (pM)12.1 (9.6)−1.4 (7.1)−1.7 (8.5)11.0 (6.8)−5.0 (7.3)**−1.4 (6.3)10 (4)−6.6 (5.7)−0.8 (4.1)
Total cholesterol (mg/dL)4.9 (0.9)−0.2 (0.5)+0.1 (0.9)5.4 (0.9)−0.5 (0.1)**−0.1 (0.8)5.4 (1.3)−0.5 (1.1)−0.5 (1.0)
Triglycerides (mg/dL)1.2 (0.6)−0.2 (0.5)+0.1 (0.4)1.3 (0.6)+0.2 (0.7)−0.3 (0.5)1.4 (0.8)−0.1 (0.8)−0.1 (0.7)
HDL cholesterol (mg/dL)1.6 (0.4)−0.1 (0.2)−0.2 (0.3)**1.5 (0.4)−0.1 (0.2)−0.1 (0.2)1.3 (0.2)+0.1 (0.1)−0.1 (0.3)
LDL cholesterol (mg/dL)2.8 (0.9)−0.1 (0.5)−0.1 (0.4)3.2 (0.8)−0.3 (0.7)+0.1 (0.7)3.5 (0.9)−0.5 (0.8)−0.6 (0.6) **

Baseline 1-year and 2-year nutrient analysis results for the 25 participants who completed 3-day food records at all three time-points are listed in Table 4. There were no significant differences among the baseline nutrient parameters by treatment group.

Table 4.  Group daily nutrient intake changes comparing baseline, year 1, and year 2 (N = 25)
Nutrient per dayBaseline Group A (n = 6)Year 1 Group AYear 2 Group ABaseline Group B (n = 10)Year 1 Group BYear 2 Group BBaseline Group C (n = 9)Year 1 Group CYear 2 Group CRDA (DRI)
  • No significant differences in baseline values among the three groups, mean (SEM).

  • *

    Significant within group A, B, or C: year 1 compared with baseline or year 2 compared with baseline (p ≤ 0.05).

  • American Heart Association Dietary Guidelines (Circulation 2000;102:2296–311).

Energy (kcal)2179 (254)1732 (189)*1754 (181)*1796 (160)1632 (173)1403 (89)*1936 (167)1537 (109)1656 (132)*2200
Carbohydrate (%)48 (3)43 (4)42 (6)51 (2)60 (3)55 (3)48 (3)55 (3)49 (3)Not available
Protein (%)15 (1)18 (1)*17 (1)15 (1)17 (1)19 (2)*16 (1)16 (1)16 (1)50 g (9%)
Fat (%)35 (3)39 (4)40 (5)33 (2)27 (2)27 (2)35 (3)31 (3)34 (1)≤30%
Saturate fat (%)12 (1)13 (1)13 (2)11 (1)8 (1)*8 (1)*12 (1)10 (1)11 (1)<10%
Cholesterol (mg)260 (57)245 (34)258 (55)188 (25)121 (19)*153 (29)236 (40)164 (31)178 (39)<300
Dietary fiber (g)17 (2)17 (3)16 (2)15 (2)19 (2)18 (2)16 (1)17 (3)17 (2)≥25
Vitamin A (μg RE)712 (81)766 (198)809 (229)702 (92)1727 (206)*1360 (230)*957 (236)961 (202)851 (152)700
βCarotene (μg RE)1593 (319)2275 (1154)2866 (1647)5107 (530)4603 (949)*3581 (852)4036 (1444)2175 (923)1879 (18)Not available
Vitamin D (μg)12 (3)8 (3)5 (2)4 (1)7 (1)*6 (1)3 (1)5 (1)5 (1)5
Vitamin E (mg TE)9 (3)13 (3)10 (2)10 (2)17 (5)10 (1)9 (1)12 (3)13 (3)15
Vitamin K (μg)77 (19)92 (25)91 (15)88 (21)125 (18)133 (19)107 (20)90 (15)103 (21)90
Vitamin C (mg)61 (9)69 (14)68 (14)99 (23)98 (13)91 (10)83 (16)89 (22)88 (25)75
Thiamin (B-1) (mg)2.2 (0.3)1.6 (0.2)1.7 (0.2)1.4 (0.1)1.6 (0.2)1.3 (0.1)1.4 (0.1)1.3 (0.2)1.4 (0.1)1.1
Riboflavin (B-2) (mg)2.1 (0.3)1.9 (0.3)1.7 (0.2)*1.5 (0.1)1.8 (0.2)1.7 (0.2)1.6 (0.2)1.5 (0.2)1.7 (0.2)1.1
Niacin (B-3) (mg)24 (3)25 (3)21 (3)19 (1)23 (3)19 (1)21 (2)18 (3)21 (2)14
Pantothenic acid (mg)5.3 (0.9)5.4 (1.2)4.4 (0.7)4.0 (0.4)6.7 (1.2)*5.3 (0.6)3.8 (0.4)4.7 (0.8)5.2 (0.8)5.0
Vitamin B-6 (mg)1.9 (0.1)1.8 (0.2)1.6 (0.2)*1.6 (0.1)2.2 (0.3)*1.9 (0.2)1.5 (0.1)1.4 (0.2)1.7 (0.2)1.3
Folate (μg)257 (36)283 (57)234 (19)237 (23)404 (35)*364 (42)*220 (23)294 (42)292 (37)400
Vitamin B-12 (μg)4.1 (1.0)5.3 (1.2)4.0 (1.2)3.1 (0.4)4.0 (0.6)4.3 (0.5)3.4 (0.6)3.1 (0.6)4.5 (0.7)2.4
Calcium (mg)891 (146)759 (128)729 (153)803 (84)903 (93)839 (140)749 (118)742 (80)740 (96)1000
Phosphorus (mg)1347 (221)1145 (171)1140 (155)1075 (79)1254 (124)1099 (107)1154 (129)1026 (89)1085 (91)700
Magnesium (mg)312 (32)278 (48)262 (25)263 (17)455 (52)*372 (49)256 (23)316 (38)328 (33)320
Iron (mg)15 (2)16 (2)12 (2)12 (1)13 (2)10 (1)13 (1)12 (2)14 (3)18
Zinc (mg)11 (2)12 (2)9 (1)9 (1)9 (1)9 (1)10 (1)8 (1)9 (1)8
Copper (mg)1.4 (0.2)1.1 (0.2)1.1 (0.1)1.1 (0.1)1.3 (0.2)1.2 (0.1)1.2 (0.1)1.2 (0.2)1.1 (0.1)1.3
Selenium (μg)135 (13)115 (16)102 (14)91 (5)103 (12)83 (6)110 (10)74 (8)*102 (11)55
Sodium (mg)4015 (508)3195 (383)*3178 (394)*2881 (348)2367 (239)2463 (163)3531 (288)2468 (175)*2415 (175)*≤2400 mg
Potassium (mg)2856 (224)2502 (380)2326 (283)2420 (145)2532 (216)2558 (260)2457 (204)2246 (228)2246 (277)Not available

Macronutrient analysis within groups showed some significant changes compared with baseline (p ≤ 0.05). Group A had a significant decrease in total energy intake (kilocalories/day; years 1 and 2) and a significant increase in the percentage of protein (year 1). Similar analysis showed that group B had a significant decrease in total energy intake (kilocalories/day; year 2) and a significant increase in the percentage of protein (year 2), percentage of saturated fat (years 1 and 2), and cholesterol (years 1). For group C, a similar within-group analysis showed a significant decrease for total daily energy intake (year 2).

Analysis of 27 micronutrients also showed some significant (p < 0.05) changes within groups compared with baseline. Group A had a significant decrease in sodium (years 1 and 2), riboflavin (year 1), and vitamin B-6 (year 1). Similar analysis showed that group B had a significant decrease in β-carotene (year 1) but a significant increase in vitamin A (years 1 and 2), vitamin D (year 1), vitamin B-6 (year 1), folate (years 1 and 2), pantothenic acid (year 1), and magnesium (year 1). For group C, a similar within-group analysis showed a significant decrease in sodium (years 1 and 2), with a significant increase in selenium (year 1).

Analysis of the daily intake of fruit and vegetable servings are listed in Table 5. There were no significant differences among the fruit and vegetable intake parameters by treatment group. Within group analysis showed that only group B showed a significant (p ≤ 0.05) increase in daily vegetable servings (years 1 and 2) and total fruit and vegetable servings (years 1 and 2), changing from a baseline value of 2.7 (0.4) total servings to 4.7 (0.7) and 5.1 (0.8) at years 1 and 2, respectively.

Table 5.  Group daily fruit and vegetable serving changes comparing baseline, year 1, and year 2 (N = 25)
Per dayBaseline group A (n = 6)Year 1 group AYear 2 group ABaseline group B (n = 10)Year 1 group BYear 2 group BBaseline group C (n = 9)Year 1 group CYear 2 group C
  • No significant differences in baseline values among the three groups, mean (SEM).

  • *

    Significant within group B, year 1 compared with baseline and year 2 compared with baseline (p ≤ 0.05).

  • U.S. Department of Agriculture Food Guide Pyramid recommendations: two to three fruit servings and three to five vegetable servings per day.

Fruits1.0 (0.4)1.0 (0.3)1.0 (0.3)1.4 (0.4)1.9 (0.4)2.6 (0.7)0.8 (0.3)1.4 (0.4)1.3 (0.5)
Range0 to 2.80 to 1.70 to 1.70 to 3.80 to 4.80 to 8.20 to 2.60 to 3.20 to 5.2
Vegetables1.9 (0.4)2.1 (0.6)2.9 (0.8)1.3 (0.3)2.8 (0.4)*2.5 (0.3)*2.5 (0.4)1.8 (0.2)1.9 (0.4)
Range0.8 to 3.20.6 to 4.00.8 to 5.70 to 2.81.0 to 4.80.8 to 4.50.9 to 4.81.0 to 3.00.7 to 4.0
Total2.9 (0.5)3.2 (0.6)3.9 (1.0)2.7 (0.4)4.7 (0.7)*5.1 (0.8)*3.3 (0.6)3.2 (0.5)3.3 (0.7)
Range1.3 to 4.50.9 to 4.70.8 to 7.40.6 to 4.51.2 to 7.80.8 to 10.31.0 to 6.31.3 to 6.00.7 to 7.2

Discussion

  1. Top of page
  2. Abstract
  3. Introduction
  4. Research Methods and Procedures
  5. Results
  6. Discussion
  7. Acknowledgments
  8. References

In the first year of this study, the efficacy of a physician–nurse team within a busy medical clinic using an intervention treatment incorporating MRs in weight loss counseling for premenopausal women was evaluated. In addition, a traditional dietitian-led group intervention treatment was compared with the same intervention using MRs. In the second year, or the maintenance phase, of the study the effectiveness of a minimal but active intervention in these same groups was studied. It has been previously shown that MRs are an effective strategy for the long-term maintenance of weight loss as well as the promotion of greater short-term weight loss compared with a traditional reduced calorie diet regimen (10) (11) (12) (13) (14). Although we previously reported on the results of a 1-year study (10), the present study is the first to compare the long-term (2-year) use of MRs with traditional food exchange strategies offered in a primary care practice or a group setting.

The significance of maintaining a healthy weight has been well-established (1) (17) (18). Overweight and obesity are associated with the development of a myriad of chronic diseases (1) that, with the attainment and maintenance of a modest weight loss, can be significantly improved (1) (17) (19) (20). Obesity and overweight are chronic conditions that require long-term treatment. The Institute of Medicine (21) of the National Academy of Sciences has proposed that successful weight loss be defined as the reduction in initial body weight of 5% or more and the maintenance of this loss for at least 1 year (21). Obesity is well-recognized for its potential health risks and the enormous public health burden that it imposes. An extensive review (1) of the causes of obesity led a National Institutes of Health expert panel to conclude that significant improvements in disease risk could be attained with moderate weight loss (5% to 10%). Therefore, the National Institutes of Health developed guidelines for health professional to use in identifying and evaluating patients with subsequent treatment to reduce weight and the concomitant diseases that are expressed with this condition (1).

The main finding in this study was that the use of one or two MRs daily promoted significantly improved weight loss and maintenance compared with a traditional diet plan. This finding is particularly encouraging because the markers for disease risk were improved in many patients. In the first year of the study in both the primary care and group setting, women who received counseling from a dietitian using the MR plan lost an average 9.1% (8.9%) of their body weight over 1 year. The women who had a traditional diet and dietary counseling lost an average of 4.1% (6.4%). The group that followed the MR plan under the supervision of a physician attained a reduction in body weight similar to the traditional diet plan group 4.3% (6.5%). Physicians are considered the main agents of change for their patients and often have the first opportunity to encourage weight control and primary prevention for obesity-related comorbidities (22) (23) (24) (25) (26). However, many practitioners do not actively counsel their overweight and obese patients despite the rapid increase in its prevalence and risks (6) (7) (8). The reasons for this reluctance have been characterized as the physician's personal perception of the causes of obesity, lack of training, insufficient office time to deal with the difficulties patients face, limited staff support, difficulty with insurance coverage, and the perceived poor success rate long-term (7) (23) (24). The time required for weight management by the physician–nurse team in our study was patterned after the customary brief clinic visit. Patients self-educated themselves from written materials at their own pace but were also able to discuss key concerns with the physician or nurse. This study, thus, extends the medical literature by suggesting that physicians can address overweight and obese participants in primary care, similar to other chronic disease risk factors.

In the second year, the weight maintenance phase of our study, using active intervention in the group setting was more effective when MRs continued to be part of the diet prescription. In those evaluated at all three time-points of the study (n = 39), no group regained all of their weight. The women in the two groups using MRs had an average loss of 9.2% and 3.4% of their initial body weight compared with 2.2% in the group not using MRs. This is an important result, because most studies show a regain of all of the weight lost after 2 years of intervention (1).

Although weight loss diets using MRs has been shown to be practical and effective, concerns exist that such diet plans could lead to substitution of MRs for key food items, like fruits and vegetables. We were able to analyze the dietary adequacy for the 25 women in this study who completed their 3-day food records at all three time-points. Although the total energy intake (kcal/d) was reduced for all groups, the nutrient profile was maintained or improved for most nutrients. The dietitian-led group incorporating MR showed an increased intake in the largest number of micronutrients, including vitamin A, vitamin D, vitamin B-6, folate, pantothenic acid, and magnesium in year 1 and vitamin A and folate in year 2. However, it is also important to put the changes in micronutrient intake in the context of the recommended dietary allowance (RDA)/dietary reference intake (DRI) recommendations. At baseline all groups reported consuming less than two-thirds of the current RDA/DRI for folate, with only the dietitian-led group without MRs continuing to report this lower consumption at 2 years. Vitamin E intake was also below two-thirds of the RDA/DRI in two of the groups at baseline, but not at the first or second years of the study. Iron intake was at this lower level only at year 2 for the dietitian-led group with MRs. Thus, part of the value of incorporating MR into a reduced caloric regimen may be the result of improved food patterns as well as the use of a nutrient-dense product that provides 15% to 100% of the %DV (daily value) (or double this amount when two products were consumed; see MR nutrient profile in the Research Methods and Procedures section).

Finally, our analysis of the adequacy of the dietary changes involved the changes in intake of fruit and vegetable servings. The current U.S. Department of Agriculture dietary guidelines and Food Guide Pyramid recommends five or more servings of fruits and vegetables daily (27). National intake data show that the United States is improving but still not achieving this goal. Data from the U.S. Department of Agriculture's 10th nationwide food consumption survey, the Continuing Survey of Food Intakes by Individuals for 1996, showed that the average total servings of fruits and vegetables for adults increased from 3.9 servings in 1989 to 1991 to 4.4 servings in 1994 to 1996 (28). Our results show that although the mean energy intake was reduced, all groups improved or maintained their intake of total daily servings of fruits and vegetables at the first and second years of the study. In particular, the dietitian-led group that received the MR plan achieved the national goal with an increase from a baseline intake of approximately three servings to five servings at years 1 and 2 of the study.

In conclusion, this study demonstrates that in premenopausal women, weight loss can be achieved and maintained over a 2-year period with lifestyle counseling using a MR strategy. For the patient, it provides a structured eating pattern that is easy to comply with and that can improve the magnitude of weight loss compared with a traditional group intervention. For the physician, it provides a practical tool that allows for ease of explanation and is effective with patients. In addition, incorporating a MR strategy into a traditional weight management program can improve food choice behavior and nutrient adequacy, even while following a reduced energy intake.

Acknowledgments

  1. Top of page
  2. Abstract
  3. Introduction
  4. Research Methods and Procedures
  5. Results
  6. Discussion
  7. Acknowledgments
  8. References

Slim-Fast Nutrition Institute, West Palm Beach, FL provided funding for the conduct of this study. Dr. Ashley has worked as a consultant and/or received research grants from food companies whose products are discussed in this article.

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  2. Abstract
  3. Introduction
  4. Research Methods and Procedures
  5. Results
  6. Discussion
  7. Acknowledgments
  8. References
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