• Assignment to a diet intervention program promotes clinically significant weight loss, compared to a control group. [ Time Frame: 22 weeks ] [ Designated as safety issue: No ]
  
• Assignment to the diet intervention program improves indices of cardiovascular risk, including plasma lipid concentrations and blood pressure, compared to a control group. [ Time Frame: 22 weeks ] [ Designated as safety issue: No ]
  
• Assignment to the diet intervention program improves glycemia in a sub-group of participants with type 2 diabetes, as indicated by mean A1c, relative to matched participants with type 2 diabetes in the control group. [ Time Frame: 22 weeks ] [ Designated as safety issue: No ]
  
• Assignment to the diet intervention, decreases the prevalence of work absenteeism, as measured by the proportion of days that a participant is absent from work, compared with assignment to a control group. [ Time Frame: 22 weeks ] [ Designated as safety issue: No ]
  

• Assignment to the diet intervention improves quality of life measures, including general mental and physical health, relative to assignment to a control group. [ Time Frame: 22 weeks ] [ Designated as safety issue: No ]
  
• Assignment to the diet intervention program promotes adherence and acceptability. [ Time Frame: 22 weeks ] [ Designated as safety issue: No ]
  

Behavioral: low-fat, vegan diet
Diet that excludes animal products (i.e. meat, diary, eggs) and keeps oils to a minimum.

Approximately 65 percent of Americans are overweight or obese. They are at increased risk for diabetes, hypertension, dyslipidemia, cardiovascular disease, arthritis, respiratory disorders, pregnancy complications, and premature death. Research has demonstrated that weight status is associated with certain types of malignancies, including endometrial, colon, gall bladder, prostate, kidney, and postmenopausal breast cancer. The total direct and indirect costs attributed to overweight and obesity amounted to 117 billion U.S. dollars in 2000. The 22-week Worksite Nutrition Study will (1) test whether a worksite intervention, which prescribes a low-fat vegan diet, is effective in promoting clinically significant weight loss, (2) evaluate whether the intervention reduces cardiovascular risk, particularly blood pressure and lipid concentrations, (3) assess whether the intervention improves glycemic control in individuals with type 2 diabetes, and (4) examine how the intervention affects work impairment and absenteeism. Participants (Group 1, n=60) at a specified worksite will be assigned to the diet intervention program, which prescribes a low-fat, vegan diet. A control group (Group 2, n=60) will be designated at a separate worksite. The participants in the control group will not receive an active intervention during the designated study period.

Participants in the active intervention will attend weekly group meetings for nutrition education on the intervention diet. Diets will be assessed, in order to monitor adherence and for the purposes of comparison, in the intervention and control groups at baseline and at weeks 11 and 22 using a 3-day dietary record. Dependent measures, including body weight, blood pressure, lipid concentrations, quality-of-life measures, and A1c (for those with diabetes) will be assessed in the intervention and control groups at weeks 0, 11, and 22.