A Prospective Evaluation of a Commercial Weight Loss Program in Overweight/Obese Adults
Authors: Habowski Scott , Lopez Hector , Sandrock Jennifer , Raub Betsy , Kedia William , Ziegenfuss Timothy 
Published: November 2023

ObjectiveAs part of a larger clinical trial comparing the effects of the Nutrisystem® program on changes in body weight and body circumferences (i.e. body size) vs. a self‐directed diet (i.e. Dietary Approaches to Stop Hypertension, DASH), the primary purpose of this prospective sub‐study was to determine if healthy overweight and obese men and women responded differently to the Nutrisystem® program by examining within‐group changes during 12 weeks of caloric restriction.MethodsForty (40) overweight/obese adults (mean ± standard error: body weight of 94.27 ± 19.15 kg and a Body Mass Index of 34.05 ± 4.89 kg/m2) entered the study. Participants started the study following a 1000 calorie a day plan for this first week and then increased to 1200 or 1500 calories per day for women and men, respectively, for the remaining 11 weeks. Subjects who had a BMI > 40 kg/m2 were also given an extra 200 calories per day through grocery food options. For the duration of the study, subjects were required to maintain their normal daily habits and to engage in a cumulative 30 minutes of physical activity per day. Changes in body weight and body size (chest, arm, waist, hip, thigh) were examined in a Per Protocol sample using repeated measures analysis of covariance. Statistical significance was accepted at p<0.05.ResultsAs displayed in the table below, women and men both lost significant amounts of body weight each week (p<0.05), with men losing more weight than women. The difference between sexes was significant at week 4 (−15.15 ± 2.02 vs. −10.12 ± 0.90 lb, p<0.048), week 8 (−24.44 ± 2.68 vs. −14.19 ± 1.12 lb, p<0.003) and week 12 (−27.94 ± 4.00 vs. −16.74 ± 1.67 lb, p<0.02). In addition, both men and women reduced body size throughout the study in a comparable fashion. At week 8, the body size reduction for men was significantly greater than women (−14.67 ± 1.73 vs. −9.11 ± 0.81 inches, p<0.008), while a trend was noted at week 12 (−15.94 ± 2.11 vs. −11.49 ± 0.99 inches, p<0.08).ConclusionIn our sample of overweight/obese men and women who followed the Nutrisystem® program for 12 weeks, significant reductions in body weight and body size occurred. Consistent with prior research, weight loss was greater in men as compared to women, though significant for both sexes.Support or Funding InformationThis study was sponsored by Nutrisystem Inc and conducted by an independent contract research organization (The Center for Applied Health Sciences, Stow, OH). Statistical analyses were completed by an independent 3rd party statistician (Omega Statistics, Murrieta, CA).This study was sponsored by Nutrisystem Inc and conducted by an independent contract research organization (The Center for Applied Health Science, Stow, OH). Statistical analyses were completed by and independent 3rd party statistician (Omega Statistics, Murrieta, CA). Data on file.

Week 1
Week 4
Week 8
Week 12

Body Weight (lb)

Women
−4.88 ± 1.10
−10.12 ± 0.90
−14.19 ± 1.12
−16.74 ± 1.67

95% Cl
(−5.85, −3.89)
(−11.92, −8.29)
(−16.45, −11.92)
(−20.13, −13.37)

Men
−6.86 ± 1.10
−15.15 ± 2.02*
24.44 ± 2.68*
−27.94 ± 4.00*

95% Cl
(−9.10, −4.64)
(−19.29, −11.02)
(−29.89, −18.98)
(−36.08, −19.77)

Total Body Circumference^ (inches)

Women
−2.71 ± 0.67
−7.58 ± 0.75
−9.11 ± 0.81
−11.49 ± 0.99

95% Cl
(−4.08, −1.34)
(−9.11, −6.05)
(−10.77, −7.44)
(−13.52, −9.46)

Men
−5.12 ±1.34
−8.81 ± 1.50
−14.67 ± 1.73*
−15.94 ± 2.11#

95% Cl
(−8.37, −2.40)
(−11.85, −5.78)
(−18.20, −11.15)
(−20.22, −11.64)

Values reported are change from baseline ± standard error of the mean.
statistically significant difference (p<0.05) between men and women at corresponding weekly time point.
a priori statistical trend (p<0.08).
sum of chest, arm, waist, hip, thigh.
95% CI = 95% confidence intervals for change from baseline.