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Randomized Trial Shows Significantly Greater Weight Loss Through Multifaceted Approach of the Jenny Craig Weight Loss Program Than That Achieved Through Usual Care

At 12 Months, Participants in the Jenny Craig Weight Loss Program Realized an Average Weight Loss of 8% of initial weight (16 lbs), Compared to an Average of 1% (less than 2 lbs) Weight Loss for Those in Control Group
San Diego, CA (April 17, 2007) -Jenny Craig today announced the 12-month results of a randomized clinical trial, as published in the April 2007 issue of Obesity, the journal of NAASO, The Obesity Society. The study, "Randomized Trial of a Multifaceted Commercial Weight Loss Program," was conducted by lead investigator, Cheryl L. Rock, PhD, RD, Professor of Family & Preventive Medicine, University of California, San Diego, in conjunction with colleagues at the university.

The results of the study show that the Jenny Craig intervention group realized an average weight loss of 8% of initial weight (16 lbs), compared to an average of less than 1% (less than 2 lbs) weight loss for those in the control group. According to the authors, the weight loss of the participant group at six months was notably maintained at one year.

"Previous studies have documented that individual factors such as prepackaged meals, a low calorie density menu, physical activity, and individualized counseling can effectively promote weight loss," said Dr. Rock.

"But what makes the program we studied unique is that it combines all of these factors into a comprehensive approach that resulted in both successful weight loss for the participant group at six months and maintenance of that loss at one year. Maintenance of this loss suggests the commencement of lifestyle changes for those individuals participating in the program," said Dr. Rock.

In addition to greater average weight loss outcomes, the Jenny Craig intervention group experienced statistically significant improvements in health parameters. In comparison, the control group did not experience the level of improvements as those in the Jenny Craig arm of the study.

Trial Key Findings

In the 24-month, randomized control trial, participants were studied to determine if the comprehensive Jenny Craig weight loss program is associated with a greater degree of weight loss in comparison to controlled conditions. 12-month results indicate that the Jenny Craig weight loss program successfully promotes weight loss, with an average weight loss of 8% (16 lbs) at both six months and one year.

Conversely, subjects in the control group lost on average less than 1% (less than 1 lb.) of their weight at six months. At twelve months, the control group had only achieved an average weight loss of less than two pounds.


Jenny Craig Group

Control Group


6 Months


12 Months


6 Months


12 Months


Change in weight, kg*

-7.2 (6.7) kgs

-7.3 (10.4) kgs

-0.3 (3.9) kgs

-0.7 (5.6) kgs

Percent change in weight

-7.8 (7.2)%

-7.8 (11.1)%

-0.3 (4.5)%

-0.7 (6.2)%

Change in body mass index, kg/m 2**

-2.6 (2.5)

-2.6 (3.9)

-0.2 (1.5)

-0.3 (2.1)

Change in hip circumference, cm**

-5.7 (5.1) cm

-6.2 (7.9) cm

-0.3 (3.3) cm

-0.3 (5.2) cm

Change in waist circumference, cm*

-7.1 (8.4) cm

-9.0 (10.6) cm

-1.1 (6.5) cm

-0.2 (7.3) cm

Change in step test, heart rate per 30 sec***

-6.4 (6.4)

-4.5 (7.0)

-2.9 (6.3)

-3.6 (6.5)

*p < 0.05 between groups at both time points
**p< 0.01 between groups at both time points
***p < 0.05 between groups at six months only

The one-year analysis revealed significantly greater change in weight, percent weight, body mass index (BMI) and waist and hip circumferences in the intervention versus control group. Completers at one year, for the Jenny Craig intervention group, realized a significant increase in HDL and a decrease in serum insulin.

Subjects in the Jenny Craig group experienced an improvement in cardiopulmonary fitness. They also demonstrated increased levels of total carotenoids, suggesting an increased consumption of vegetables and fruits, possibly due to Jenny Craig's emphasis on these foods.

Variables (mean [SD])

Jenny Craig Group

Control Group



6 months


12 months




6 Months


12 months


Alpha-carotene, umol/L*

0.12 (0.14)

0.13 (0.11)

0.18 (0.15)**

0.13 (0.11)

0.09 (0.07)§

0.16 (0.14)

Beta-carotene, umol/L*

0.48 (0.65)

0.73 (0.73) §

0.67 (0.57)**

0.46 (0.39)

0.42 (0.32)

0.50 (0.31)**

Total carotenoids, umol/L*

1.82 (1.2)

2.12 (1.18)

2.33 (1.04)

1.90 (0.81)

1.81 (0.65)

2.26 (0.69)

HDL cholesterol, mg/dL

50 (15)

51 (13)

61 (15)**

52 (13)

53 (11)

56 (17)

LDL cholesterol, mg/dL

113 (40)

109 (32)

104 (26)

121 (35)

119 (26)

120 (31)

Sex hormone binding globulin, nmol/L

56.4 (49.6)

72.7 (59.3)

72.8 (50.7)

68.9 (74.5)

79.4 (69.3)

69.8 (43.2)

Insulin, uU/ml*+

22.7 (12.3)

17.7 (9.9)

18.8 (10.8)

17.9 (8.4)

19.6 (10.0)

19.7 (9.2)

* Intervention group had significantly greater change between baseline and six months than the control group, p < 0.05, independent t-test
** Significant change from baseline to 12 months, within-group paired t-test
§ Significant change from baseline to six months, within group paired t-test
+ Intervention group had marginally greater change between baseline and 12 months than the control group, p=0.05, independent t-test

"The unfortunate reality is that 34% of the females in the U.S. are obese. However, with physicians having a limited amount of time and a large number of overweight patients to treat, it is difficult to successfully address the issue solely in the primary care setting," said Lisa Talamini, RD, Chief Nutritionist and Director of Program Development for Jenny Craig, Inc. "This study helps demonstrate that Jenny Craig's one-on-one approach to weight management is an efficacious option for clinicians looking for a scientifically proven weight loss program to recommend to their patients."

Randomized Trial Design

Individuals eligible for the study were women aged =18 years, who had a BMI >25, a weight of <40kg/m 2, (minimum of 15 kg over ideal weight by 1983 Metropolitan Life tables), and who were able to participate in clinic visits and other study activities. Individuals with severe disabilities that prohibit physical activity, those with a co-morbid disease, or those who were pregnant, breastfeeding or currently involved in another study or weight loss program, were excluded from the study. A total of 70 women participated in the study, with 35 in the usual care or control group and 35 in the Jenny Craig or intervention group.

Subjects were stratified by BMI and age and randomly assigned to the Jenny Craig weight loss program or usual care. The Jenny Craig arm subjects received all Jenny Craig weight loss program consultations, material and food as needed, free of charge. The usual care (control) arm subjects received consultation with a research dietitian, free of charge, at randomization and sixteen weeks, supplemented by publicly available print weight management material.

Data collection and measurements were obtained at four time points: baseline, 16 weeks (weight and circumferences only), 6 months and 12 months. Further data collection will occur at 18 and 24 months. Anthropometric measures included height, weight, and waist and hip circumference. Cardiopulmonary fitness was assessed through the use of a step test.

Blood samples were collected to measure plasma cholesterol, triglycerides, HDL cholesterol plasma carotenoids, and serum insulin and sex-hormone binding globulin concentrations.

Analysis was conducted for both intent-to-treat and completer groups. The primary outcome of interest was change in body weight from baseline to follow-up time points. Blood and step test measures were analyzed using paired t-test comparisons within Jenny Craig and control groups, and independent t-test analysis at baseline and follow-up.

About Jenny Craig

Jenny Craig, Inc. based in Carlsbad, CA, is one of the world's largest weight management companies, with approximately 650 Centres in the United States, Canada, Australia, New Zealand and Puerto Rico. Jenny Craig and the Jenny Direct at-home program are safe, science-based weight loss programs, based on a foundation of components that research has shown to be effective for long-term healthy weight management. Developed by registered dietitians in consultation with a distinguished Medical Advisory Board, the Jenny Craig program reflects the latest research on nutrition, exercise and cognitive-behavioral modification as it applies to weight management and disease prevention. The Jenny Craig weight loss program is a comprehensive Food-Body-Mind plan that helps clients manage their weight by creating a healthy relationship with food, building an active lifestyle and developing a balanced approach to living.