The number of overweight and obese adults in the United States is increasing at a rapid rate. A "stepped-care" weight loss program, which at key times increases the frequency of contact between an individual trying to lose weight and the program staff, may be beneficial for achieving long-term weight loss. This study will compare a standard behavioral weight loss program with a "stepped-care" weight loss program in their abilities to help people who are overweight or obese to lose weight.

Obesity can lead to many serious health conditions, including high blood pressure, diabetes, heart disease, and stroke. It is estimated that more than 65% of adults in the United States are overweight or obese, which is a significant increase over the past two to three decades. Although numerous studies have identified successful programs that help people achieve initial weight loss, few weight loss programs have shown promise for long-term success. Research has shown that a weight loss program in which there is continued contact between the program leader and the participant may improve long-term weight loss outcomes. In addition, a stepped-care approach to weight loss, in which contact between the participant and program leader increases when needed to achieve the next weight loss goal, may be beneficial. This study will examine whether a long-term weight loss program delivered in a stepped-care manner results in greater weight loss than does a standard behavioral weight loss program. Study researchers will also evaluate the cost effectiveness of both programs.

Participants in this 18-month study will be randomly assigned to either a standard behavioral weight loss program or a stepped-care weight loss program. Participants in the standard behavioral weight loss program will attend group meetings once a week for Months 1 to 6, every other week for Months 7 to 12, and once a month for Months 13 to 18. The group meetings will focus on modifying eating habits and physical activity behaviors to improve weight loss. Participants in the stepped-care weight loss program will take part in a combination of treatments, whose timing and intensity will depend on the participants' abilities to achieve predetermined weight loss goals. These treatments may include attending monthly group meetings, receiving weekly weight loss information in the mail, receiving telephone calls from study staff to discuss weight loss behaviors, taking part in individual sessions with study staff to discuss weight loss, and receiving meal replacements (e.g., Slim Fast shakes, meal bars). Participants who do not achieve their weight loss goals at select time points during the study will receive more individual attention from study staff. All participants will follow a diet that focuses on decreasing calories and fat. They will be instructed to follow a walking program 5 days a week and to keep a food and exercise diary. Participants will also have access to a Web site that will include a study calendar and information about how to change eating and exercise behaviors; the use of this Web site is optional.

Study visits will occur at baseline and Months 3, 6, 9, 12, 15, and 18. At each visit, participants' weight and height will be measured, and participants will complete questionnaires about their mood, general health, and exercise and diet habits. At baseline and Months 6, 12, and 18, participants will undergo measurements of blood pressure, fat, muscle, and waist and hip circumferences. Also at these times, physical fitness levels will be measured through a treadmill walking activity, during which an electrocardiogram (ECG) will record heart rate. For 7 consecutive days at baseline and Months 6, 12, and 18, participants will wear an activity monitor to measure physical activity levels.

Inclusion Criteria:

• Body mass index (BMI) between 25.0 and 39.9 kg/m2

Exclusion Criteria:

• Reports losing more than 5% of current body weight in the 6 months before study entry
• Participated in a research project involving weight loss or physical activity in the 6 months before study entry
• Pregnant during the 6 months before study entry, currently breastfeeding, or planning to become pregnant in the 18 months after study entry
• Current treatment for any medical condition that could affect body weight (e.g., diabetes mellitus, cancer)
• History of heart attack or heart surgery, including bypass or angioplasty
• Currently taking medication that would affect heart rate or blood pressure responses to exercise (e.g., beta blockers)
• Currently taking medication that could affect metabolism or change body weight (e.g., synthroid)
• Currently being treated for psychological issues or has taken psychotropic medications in the 6 months before study entry

This study was not designed to test for weight loss equivalency between conditions. This study is unable to determined if an alternative intensity or frequency of intervention steps would be more or less effective for weight loss.