Participants in the control group will attend an individual session during month 1, and a monthly face-to-face group meeting during months 2-6. The sessions will provide attention, social interaction, and physician-based health education. Participants will receive a newsletter during months 9 and 15.

The investigators will measure self-reported physical function using the WOMAC (scores will be pulled from the KOOS Questionnaire in which the WOMAC is embedded). The LK version asks participants to indicate on a scale from 0 (none) to 4 (extreme) the degree of difficulty experienced in the last week due to knee OA. Individual scores for the 17 items are totaled to generate a summary score that could range from 0-68, with higher scores indicating poorer function.

Compare the effects of a 6-month weight-loss maintenance intervention grounded in social cognitive theory to a health education intervention on health-related quality of life (SF-36) subsequent to a 12-month unsupervised follow-up period. Two summary scores are acquired: physical health and mental health. Range=0-100. Higher scores indicate better health.

The primary mobility measure will be 6-minute walk distance. Participants are told to walk as far as possible in 6 minutes on an established course.

Compare the effects of a 6-month weight-loss maintenance intervention grounded in social cognitive theory to a health education intervention on self-efficacy. The perceived stress questionnaire will measure the degree to which people perceive their lives as stressful. Range = 0-40. Higher numbers indicate higher stress.

Compare the effects of a 6-month weight-loss maintenance intervention grounded in social cognitive theory to a health education intervention on self-efficacy. The walking efficacy for duration scale measures one's ability to walk/jog at a moderately fast pace for various durations. Range 0-100. A higher score indicates a higher self-efficacy.

Compare the effects of a 6-month weight-loss maintenance intervention grounded in social cognitive theory to a health education intervention on self-efficacy. The Positive and Negative Affect (PANAS) measures both positive and negative affect, leading to more insightful outlooks regarding participants' feeling states. This scale consists of 20 items that reflect the intensity of how the participant "feels" right now. Range=10-50 for each subscale. A higher score for positive affect indicates a higher level of positive affect. A higher score for negative affect indicates a higher level of negative affect.

Compare the effects of a 6-month weight-loss maintenance intervention grounded in social cognitive theory to a health education intervention on self-efficacy. The gait efficacy/environmental efficacy scale will ask the participants' confidence in performing certain activities. Confidence in performing activities. Participants will be asked to indicate their level of confidence being able to complete different tasks. Range=0-100. A higher score indicates higher self-efficacy.

Compare the effects of a 6-month weight-loss maintenance intervention grounded in social cognitive theory to a health education intervention on self-efficacy. The Satisfaction with life scale is focused to assess global life satisfaction. Range=5 to 35. A higher scale indicates a higher level of life satisfaction.

Compare the effects of a 6-month weight-loss maintenance intervention grounded in social cognitive theory to a health education intervention on self-efficacy. The Weight Efficacy Lifestyle Questionnaire (WEL) is a 20-item measure employed to assess self-efficacy for weight management. Range=0 to 180. Higher numbers indicate better confidence.

Compare the effects of a 6-month weight-loss maintenance intervention grounded in social cognitive theory to a health education intervention on self-efficacy. The adherence questionnaire is designed to assess beliefs in one's ability (confidence) to continue exercising at various intensities and frequencies. Range=0-100. A higher score indicates higher self-efficacy.

Compare the effects of a 6-month weight-loss maintenance intervention grounded in social cognitive theory to a health education intervention on self-efficacy. The Barriers Self-Efficacy to Exercise measures confidence in dealing with barriers to exercise. Range=0-100. Higher numbers indicate higher confidence.

Compare the effects of a 6-month weight-loss maintenance intervention grounded in social cognitive theory to a health education intervention on self-efficacy. The MOEES questionnaire consists of three subscales: physical outcome expectations (score range 6-30), social outcome expectations (score range 4-20), and self-evaluative outcome expectations (score range 5-25). Each subscale is scored by summing the numerical ratings for each response. Higher scores are indicative of higher levels of outcome expectations for exercise.

Compare the effects of a 6-month weight-loss maintenance intervention grounded in social cognitive theory to a health education intervention on self-efficacy. The perceived barriers questionnaire measures a person's perceptions to barriers to performing exercise. The questionnaire is scored by finding the mean for each response (range = 1-5). Higher scores indicate higher perception of barriers.

Compare the effects of a 6-month weight-loss maintenance intervention grounded in social cognitive theory to a health education intervention on self-efficacy for maintaining weight loss. Range=0-100. Higher scores indicate more confidence in maintaining weight loss.

Resource utilization will be collected by questionnaire. MD and non-MD office visits will be collected via self-report with domains including visits to clinicians (physicians, nurses, physical therapists, others), tests, medications, injections, surgery, alternative therapies. The number of visits associated with utilization of each of 4 domains, MD visits, non-MD visits, ED visits, and inpatient stays, will be examined.

The Work Productivity and Activity Impairment index (WPAI) will be used to assess absenteeism and reduced productivity while at work (presenteeism). Outcome (OC) scores can be derived from the WPAI: OC1, percent work time missed due to health, (percentage of absenteeism); percent impairment while working due to health, (percentage of presenteeism); percent overall work impairment due to health, percent activity impairment due to health. For all 4 outcomes, greater scores (range 0-100%) indicate greater impact of health.

The PCS questionnaire will be used to assess catastrophizing (rumination, magnification, and helplessness). The PCS total score is computed by summing responses to all 13 items. PCS total scores range from 0 - 52. Lower scores indicate less pain.

The KOOS questionnaire will be used to assess the patient's opinion about their knee and associated problems. The KOOS evaluates both short-term and long-term consequences of knee injury and also consequences of primary osteoarthritis (OA). It holds 42 items in five separately scored subscales: 1) KOOS Pain; (2) KOOS Symptoms: Other symptoms such as swelling, restricted range of motion and mechanical symptoms; (3) KOOS ADL: Disability on the level of daily activities; (4) KOOS Sport/Rec: Disability on a level physically more demanding than activities of daily living; (5) KOOS QOL: Quality of life, mental and social aspects such as awareness and lifestyle changes. Standardized answer options are given (5 Likert boxes) and each question is assigned a score from 0 to 4. A normalized score (100 indicating no symptoms and 0 indicating extreme symptoms) is calculated for each subscale.

The ICOAP assesses pain in individuals with knee osteoarthritis taking into account both constant and intermittent pain experiences. Individual items are scored from 0 to 4. Each subscale (intermittent pain; constant pain; and total pain) are averaged. Lower numbers indicate lower pain.

Behavioral Risk Factor Surveillance System measures health literacy. Lower scores indicate higher literacy.

The MOCA will be used to measure cognitive function. Scores range 0-30. Higher scores indicate higher cognitive functioning.

The Brief Resilience Scale will be used to measure resilience. The brief resilience scale (BRS) contains 6 items. The BRS is scored by reverse coding negatively worded questions (2, 4, and 6) and finding the mean of the six items. Range= 1-5. Lower scores indicate less resilience.

Physical activity will be measured by The Physical Activity Scale for the Elderly (PASE). 1-6 are scored in terms of hours per day over a 7-day period. Items 7-12 are scored as 1= engaged in activity or 0=did not engage in activity during the previous seven days. Scores range 0-100. Higher scores indicate more activity.

Depression will be measured using the Center for Epidemiologic Studies Depression Scale (CES-D). The CES-D contains 20-items and measures how often over the past week persons experienced symptoms associated with depression, such as restless sleep, poor appetite, and feeling lonely. Response options range from 0 to 3 for each item (0 = Rarely or None of the Time, 1 = Some or Little of the Time, 2 = Moderately or Much of the time, 3 = Most or Almost All the Time). Scores range from 0 to 60, with high scores indicating greater depressive symptoms.

Compare the effects of a 6-month weight-loss maintenance intervention grounded in social cognitive theory to a health education intervention on health-related quality of life. The EQ-5D comprises 5 dimensions (mobility, self-care, usual activities, pain/discomfort, anxiety/depression). Each dimension has 5 levels: no problems, slight problems, moderate problems, severe problems and extreme problems. Responses results in a 1-digit number that expresses the level selected for that dimension. The digits for the five dimensions can be combined into a 5-digit number that describes the patient's health state. The EQ-5D questionnaire also includes a Visual Analog Scale (VAS), by which respondents can report their perceived health status with a grade ranging from 0 (the worst possible health status) to 100 (the best possible health status).