- Click here for explanation of classification scheme.

To test whether the multifaceted Jenny Craig (JC) intervention is associated with a greater degree of weight loss and maintenance of that loss in overweight or obese women compared with control conditions.

• Age 18 years and older
• Initial BMI at least 25.0kg/m² (overweight or obese) and less than 40kg/m² and a minimum of 15kg over ideal weight, as defined by the 1983 Metropolitan Life Insurance tables
• Willing and able to participate in clinic visits and JC facility interactions at specified intervals and to maintain contact with the investigators for two years
• Willing to allow blood collections; and capable of performing a simple step test for assessing cardiopulmonary fitness.

• Those who were unable to be physically active because of severe disability (e.g., severe arthritic conditions) or who reported a history or presence of a comorbid disease for which diet modification and increased physical activity might be contraindicated were not included
• Those who reported being currently pregnant or breastfeeding or planning a pregnancy within the next two years
• Current active involvement in another diet intervention study or organized weight loss program
• Those having a history or presence of a significant psychiatric disorder or any other condition that, in the investigator’s judgment, would interfere with participation in the trial also disqualified women from participating.

Recruitment

Not reported.

Design

• Randomized controlled trial
• Participants were stratified by BMI (25.0kg/m² to 29.9kg/m² vs. 30.0kg/m²) and age (under 40 and over 40 years) and randomly assigned to one of the two study groups: Intervention (JC) or Control.

Blinding Used

Implied with measurements.

Intervention

The intervention arm consisted of referral to a conveniently located community-based JC facility, including the establishment of an initial appointment to begin the program. Subjects assigned to the commercial weight loss program intervention received all program materials, including pre-packaged prepared foods as needed to achieve a meal plan, free-of-charge. The food component consists of prescribing an energy-reduced diet (typically 1,200kcal to 2,000kcal per day, individualized based on energy requirements) that includes pre-packaged prepared food items that incorporate (and are accompanied by) increased vegetables, fruit and other additional strategies to reduce the energy density of the diet. The pre-packaged foods are generally provided at the weekly interactions at a community-based facility and food selections are determined by the preferences of the client and how the products fit into a nutritionally complete meal plan. The average energy contribution of the pre-packaged foods during that initial period is 820kcal per day, so that within a prescribed energy intake of 1,200kcal to 2,300kcal per day, the pre-packaged food would provide 35% to 68% of energy for clients who choose not to deviate from the plan.

Participants assigned to the Usual Care Control Group were provided consultation at baseline (after randomization) and again at 16 weeks with a research staff dietitian, who also provided publicly available print material that described dietary and physical activity guidelines to promote weight loss and maintenance. The dietitian initially discussed the interpretation of the participant’s anthropometric data and the concepts of healthy weight and energy balance. Baseline energy requirements for weight maintenance were then calculated and an energy intake level (accompanied by a menu plan based on food groups) to achieve a weight loss of 10% over a six-month period was prescribed, involving a deficit of 500kcal to 1,000kcal per day, as per current recommendations. Specific sample meal plans and recommendations to increase physical activity were provided to each participant. Written materials and resources for useful strategies and skills, such as reading food labels, estimating serving sizes and eating outside the home, were provided as well as information for healthy food choices (e.g., the US Department of Agriculture Food Guide Pyramid). Progress was reviewed and concepts and strategies were further discussed in the follow-up counseling session.

Statistical Analysis

Changes in anthropometric measures (change in weight, BMI, waist and hip circumferences and percentage weight change) were compared between the two groups at six months and at 12 months, using two-sample T-tests. Changes in step test (heart rate over 30 seconds) and changes in BDI and EDE-Q scores in the two study groups were also compared using two-sample T-tests. The drop-out rate was low [none at six months and five (7%) at 12 months] and we performed both an intent-to-treat and completers analysis on the 12-month data, substituting baseline values for any subjects for whom 12-month data were missing.

Timing of Measurements

Information about demographic characteristics was collected by telephone at the time of recruitment and as part of the initial interview. Before the initial clinic visit, participants received detailed instructions on how to prepare for a clinic visit and the interview and written questionnaires were completed at the clinic visits. Trained staff obtained anthropometric measures, BMI was calculated with these measurements and a step test was conducted with each participant at the baseline and six- and 12-month clinic visits. Data collection (anthropometric measures, biochemical laboratory assays, questionnaires and step test) for all subjects occurred at three clinic visits: At baseline, at six and at 12 months. Information about demographic characteristics and weight history was collected only at baseline.

Dependent Variables

• Anthropometric measurements (height, weight, waist and hip circumferences)
• Three-minute step test (aerobic fitness)
• Blood measures
• Eating disorder examination questionnaire (EDE-Q)
• Beck depression inventory.

Independent Variables

Group assignment: JC Intervention vs. Usual Care Control. 

Control Variables

Timing of measurements.

Initial N

A total of 70 women were randomized (35 in Usual Care Control, 35 in JC Intervention)

Attrition (Final N)

• Six months: 35 in Usual Care, 35 in JC Intervention
• 12 months: 33 in Usual Care, 32 in JC Intervention.

Age

Usual Care: 40±12 years
JC Intervention: 42±11 years.

Ethnicity

White: 57% in both groups
Hispanic: 31% in the Usual Care Group; 14% in the JC Intervention Group
African-American: 3% in the Usual Care Group; in the JC Intervention Group
Asian-American: 3% both groups
Other: 6% in the Usual Care Group; 9% in the JC Intervention Group.

Other Relevant Demographics

• Anthropometrics: NS differences between groups at baseline
  • BMI: 33.8±3.4kg/m² in the Usual Care Group; 34.2±3.7kg/m² in the JC Intervention Group
  • Weight: 89.6±9.4kg in the Usual Care Group; 94.4±12.2kg in the JC Intervention Group
• Location: San Diego, CA, USA.

Key Findings
Change in weight, intent-to-treat analysis

Variables		Intervention (JC) Group	UC Control Group	Statistical Significance of Group Difference
Change in weight (kg)	6 months	-7.2±6.7	-0.3±3.9	P<0.01 between groups at both 6 and 12 months
	12 months	-6.6±10.2	-0.7±5.5
Change in percent weight	6 months	-7.8±7.2	-0.3±4.5	P<0.01 between groups at both 6 and 12 months
	12 months	-7.1±10.8	-0.7±6.0
Change in BMI (kg/m2)	6 months	-2.6±2.5	-0.2±1.5	P<0.01 between groups at both 6 and 12 months
	12 months	-2.4±3.8	-0.3±2.1

• After 12 months, change in weight was 7.3±10.4kg (7.8±11.1%) in the Intervention Group vs. 0.7+5.6kg (0.7±6.2%) in the Control Group (P<0.01) for those who completed the trial
• Importantly, at both follow-up time-points, the Intervention Group lost significantly more weight, BMI and waist and hip circumferences than the Usual Care Control Group (P<0.01)
• Results from this study demonstrate that a commercial diet and lifestyle modification program that incorporates several specific strategies (individual counseling, low-energy density diet, pre-packaged foods and increased physical activity) successfully facilitated a weight loss of 8% of initial weight that was notably maintained at one year.

Other Findings

• The two groups did not differ on their EDE-Q and BDI scores, with both groups showing very small improvements on each measure (data not shown)
• Women assigned to the commercial weight loss program intervention experienced increases in plasma concentrations of alpha-carotene, beta-carotene, lycopene and HDL-cholesterol (P<0.01 paired T-tests) between baseline and 12 months
• The Usual Care Control Group did not show any change in HDL-cholesterol or alpha-carotene concentrations, although the beta-carotene and lycopene concentrations also increased in the Control Group women
• Total carotenoids, alpha-carotene and beta-carotene increased more in the Intervention Group than in the Usual Care Control Group between baseline and six months (P<0.05), but the difference was not sustained over 12 months. A key aspect of the approach to dietary guidance in the JC program is to encourage increased intake of vegetables and fruit as one approach to reducing the energy density of the diet. The increase in plasma carotenoids observed in this study confirms this change in diet composition.

A commercial weight loss program that promotes diet and lifestyle modification successfully facilitates weight loss, which is notably maintained at one year.

Industry:	Jenny Craig, Inc
In-Kind support reported by Industry:	Yes

Only women studied.