A Short‐term Prospective Evaluation of a Commercially‐Available Weight Loss Program
Authors: Cook Chad M , Kaden Valerie N , Huebner Margie , Kelley Kathleen M 
Published: November 2023

BackgroundPrevious research has shown that large initial weight loss during the first few weeks of an intervention is predictive of successful longer‐term weight loss and weight loss maintenance. Many commercial products/programs are readily available to the weight conscious consumer; however, evidence specific to their weight‐loss promoting effectiveness is often lacking.ObjectiveThe aim of this single‐arm study was to examine the magnitude of changes in weight and related outcomes achievable at two weeks when generally healthy overweight and obese adults followed a commercially‐available structured weight loss program providing 1000 kcal/d of pre‐packed portion controlled foods for one week, and then transitioned to a more modest reduced calorie program (1200 to 1800 kcal/day) for the second week.MethodsSixty overweight/obese adults (n = 42 women, n = 18 men) with a mean ± standard error of the mean (SEM) age of 51.9 ± 1.4 y, body weight of 202.9 ± 4.1 lb, and body mass index of 33.6 ± 0.6 kg/m2 at screening were enrolled. Subjects consumed 1000 kcal/d of Nutrisystem® pre‐packaged portion controlled foods and shakes for one week. During the second week, participants transitioned to a more modest reduced calorie program (1200, 1500, or 1800 kcal/d program), as determined by an energy needs calculation performed using the Mifflin‐St. Jeor resting metabolic rate equation multiplied by an a standardized physical activity level. Changes in body weight, waist circumference, and blood pressure were outcomes of interest. The results presented herein represent all 60 participants that completed the study and were included in an intent‐to‐treat (ITT) analysis.ResultsData are reported as the least squares mean (LSM) and the 95% confidence interval (CI). Fifty seven (57) out of 60 subjects in the ITT analysis lost body weight over the 2‐week study period, with a statistically significant LSM change from baseline of −5.3 lbs (−10.3, −0.3;p = 0.037) and a maximum weight loss of −12.2 lb. More than half of the subjects (53%) lost ≥5 lb at the end of the study. A majority of subjects also experienced statistically significant reductions in waist circumference at one and two weeks, with significant LSM changes from baseline of −1.0 (−2.0, −0.02) in (p = 0.047) and −1.5 (−2.4, −0.5) in (p = 0.004) after one and two weeks, respectively. There was no change in systolic (−2.6 [−7.2, 2.0] mm Hg, p = 0.264) or diastolic (−1.3 [−4.8, 2.2] mm Hg, p = 0.454) blood pressure at the end of the 2‐week intervention. The most commonly reported adverse events (AE) were related to gastrointestinal symptoms reported by 3 subjects, including flatulence (n = 1), diarrhea (n = 1) and constipation (n =3), but most were deemed mild or moderate in severity.ConclusionThis commercially‐available weight loss program was well‐tolerated and effective in producing meaningful weight loss of more than 5 lb over a 2‐week period, with corresponding average reductions in waist circumference of approximately 1.5 in.Support or Funding InformationThis study was funded by Nutrisystem, Inc.