There is a body of evidence that has evaluated the effect of Weight Watchers, a commercially available weight loss program, on changes in body weight. The current investigation aims to add to this body of evidence by providing additional data on changes in body weight and enhance the current evidence-base in regards to evaluating other health-related outcomes.

There is little evidence that demonstrates whether or not the weight loss as a result of the Weight Watchers program elicits changes in health-related functional outcomes such as aerobic capacity, flexibility, sleep, and other psychological measures. Additionally, within a scientific research protocol, measures of adherence and satisfaction will also be evaluated evaluated. This study will evaluate these outcomes beyond weight changes achieved across the 24-week program.

Inclusion Criteria:

• Male or female ages 18-75 years. Set "soft quotas" on the number of male and female participants. The desire is to have an 80% female/20% male split.

• Willing to enroll in the Weight Watchers Program

• With or without previous Weight Watchers experience Set maximum quota on the number of participants with previous Weight Watchers experience at 65%.

• Self-reported height/weight resulting in a Body Mass Index (BMI) of 25 to 43 (will re-screen at facility).

• Self report that he/she feels the need to lose weight.

• Willing to discontinue any current over-the-counter (OTC) supplements not recommended/prescribed by physician, with the exception of multivitamins or other vitamin supplement.

• Willing to follow recommendations required by study protocol.

• Willing to include demographic information (e.g., ethnicity, income and education).

• Use of a personal iPhone on a daily basis

  1. iPhone must have iOS 8.0 or later
  2. Must have at least 600 MB of available storage to accommodate the size of the app

• The willingness and ability to navigate and use applications on their iPhone on a daily basis (minimum training will be provided)

• Reliable home Wi-Fi access

• Ability to commit to attending up to 27 study visits in approximately 26 weeks:

  1. Ability to commit (to best of their ability) to attending weekly meetings, 30-60 minutes in duration, on the same day and at the same time each week for 24 consecutive weeks.
  2. Ability to commit to up to 3 additional study visits at Weeks 0, 12 and 24, with each visit being 60-90 minutes in duration to complete assessments (height, weight, questionnaires, physical measures).

Exclusion Criteria:

• Currently, or within the last 6 months, trying to lose weight by following guidelines (e.g., self-initiated programs such as 5-2, or Atkins) or a structured weight-loss program (e.g., at a medical center, university, commercial programs)
• A member of Weight Watchers within the past 12 months.
• Involved in any other related research studies and self-report agreeing to not enroll in other studies that may affect weight or health outcomes over the next 12 months.
• Pregnant or nursing, or planning on becoming pregnant over the next 9 months.
• Weight loss of ≥ 5 kg in the previous 6 months.
• History of clinically diagnosed eating disorder.
• Reported health problems that make weight loss or unsupervised exercise unsafe or unreasonable (e.g., orthopedic limitations, heart problems)
• Untreated thyroid disease or any changes (type or dose) in thyroid medication in last 6 months.
• Taking any prescription medication with known effects on appetite or weight (e.g., oral steroids, weight loss medications such as Qysmia, Contrave, etc.) with the exception of subjects on a stable dose of Selective Serotonin Reuptake Inhibitors (SSRIs) for 6 months
• Diuretic use for hypertension over 1.5mg per day
• Chronic/inflammatory gastrointestinal disorders (irritable bowel syndrome acceptable).
• History of heart problems (e.g., angina, bypass surgery, myocardial infarction, etc.) within previous 6 months.
• Resting systolic blood pressure >160 mmHg or resting diastolic blood pressure >100 mmHg
• Diagnosis of type 1 or type 2 diabetes.
• Previous surgical procedure for weight loss.
• Major surgery within the previous 6 months.
• Presence of implanted cardiac defibrillator or pacemaker.
• History of cancer within past 5 years or current treatment for cancer (completely resected basal or squamous cell carcinoma acceptable if treatment completed more than 6 months prior to enrollment).
• Hospitalization for psychiatric problems during the past 12 months.
• Consuming more than 14 alcoholic drinks per week or not more than 3 drinks per day.
• Planning to relocate in the next 9 months.