Dietary protein is a key element of most effective weight loss regimens. This study will investigate the effects of consuming soy protein on body composition and cardiometabolic health within the context of an effective weight loss and maintenance program called the Colorado Diet.

This is a randomized study involving 60 study subjects (30 per arm). Investigators plan to enroll 72 subjects (36 per arm) in order to allow for any potential drop outs with the goal of 60 study completers. Investigators will compare the efficacy of inducing weight loss of two treatment arms all based on the Colorado Diet. Subjects will be randomly assigned to one of two study arms and instructed to follow the Colorado Diet by participating in weekly Colorado Diet group classes (State of Slim class). There will be 4 classes of 18 subjects each (two classes for each treatment group). Subjects will be followed in the study for 12 months. Subjects will be randomized into one of two treatment groups as follows:

• Group 1 will participate in a State of Slim group class, receive a State of Slim book (describing the Colorado Diet), and will then purchase food items allowed in the Colorado Diet from the lists of acceptable foods in the State of Slim book.
• Group 2 will participate in a State of Slim class, receive the State of Slim book, and be provided soy protein foods to be consumed as part of the Colorado Diet (subjects will receive up to 3 foods with approximately 20g of soy protein each, per day).

Inclusion Criteria:

1. Males and females ages 18 - 55 years
2. BMI between 27-40
3. Weight stable (have not lost or gained more than 10 pounds in the last 3 months)
4. Generally healthy
5. Able to exercise 70 minutes per day at moderate intensity
6. Willing and able to participate in a State of Slim group class for the first 16 weeks of the study and willing to participate in 5 study visits over the 12 month study period.

Exclusion Criteria:

1. Pregnant or trying to become pregnant.
2. Diagnosis of type 1 or type 2 diabetes
3. Individuals following a vegetarian only diet
4. Food allergies (to soy, dairy, wheat/gluten, eggs, or peanuts)
5. Taking medications that could cause weight loss or weight gain or alter plasma lipids (such as steroids, tricyclic antidepressants, chemotherapy, antipsychotics, prescribed or over-the-counter weight loss agents, statins, fibrates, niacin, etc). Oral contraceptives can be used as long as subject agrees to not change use of these during the study. Multivitamins containing niacin can be used as long as subject agrees to not change use of these during the study.
6. Known renal disease
7. hypothyroidism
8. Current alcohol or drug abuse or dependence (Subjects who have quit smoking in the last 6 months will be excluded. Smokers whose smoking habits have been stable for the last 6 months and which remain stable during the study can be included).
9. Any medical condition for which following a diet and/or 70 minutes of exercise daily would be inadvisable
10. LDL cholesterol levels above 190 mg/dl or triglycerides above 400 mg/dl.

Banked blood samples may be shared with other researchers (with subject consent)