The purpose of this study is to test the effects of a modified carbohydrate diet versus a portion controlled diet in overweight or obese men and women on body weight.

Inclusion Criteria:

• Men and women 18 to 65 years of age.
• Waist circumference measurement at Visit 1 (week -1) of ³ 87 cm for females and ³ 90 cm for males.
• Subject agrees to discontinue all use of supplements or multivitamins (except for those provided during study period) by Visit 2 (week 0).
• Normally active and judged to be in good health on the basis of medical history and routine laboratory tests.
• Subject must be willing to follow the assigned diet and maintain usual physical activity level throughout the trial.
• Subject understands the procedures and requirements of the study by providing written informed consent and authorization for protected health information disclosure.

Exclusion Criteria:

• Weight loss of > 10 lb in the two months prior to screening.
• Body mass index (BMI) > 37.0 kg/m2.
• Current smoker (any cigarette use) or history of smoking within 6 months prior to screening.
• Postmenopausal women who are current users of hormone therapy or have discontinued hormone therapy within 2 months prior to screening.
• History or presence of significant cardiac, renal, hepatic, pulmonary, biliary, or endocrine disorders.
• Uncontrolled hypertension (systolic blood pressure ³ 160 mm Hg or diastolic blood pressure ³ 100 mm Hg on two consecutive visits).
• History of recurrent nephrolithiasis, or an acute episode of nephrolithiasis within the last year prior to screening.
• History of symptomatic cholelithiasis, unless subject has undergone cholecystectomy.
• History of gastrointestinal surgery for weight-reducing purposes.
• Active gastrointestinal disorders such as peptic ulcer disease or malabsorption syndromes (controlled lactose intolerance or gastroesophageal reflux disease are acceptable.)
• Pancreatic disease: pancreatic enzyme deficiency, history of pancreatitis.
• Fasting blood glucose ≥ 126 mg/dL at visit 1 or diagnosed diabetes mellitus.
• Use of any weight loss medications, supplements, programs, or meal replacement products intended to alter body weight within 4 weeks of the screening visit or during the course of the study. Occasional use of meal replacement bars or shakes as snacks is acceptable.
• History or presence of cancer in the past 2 years, except for successfully resected basal cell carcinoma of the skin.
• Psychiatric disorders requiring medications (i.e., selective serotonin reuptake inhibitors) or which could interfere with the subject's compliance to the requirements of the protocol.
• History or current presence of any diagnosed eating disorders (binge eating, bulimia, history of anorexia).
• Use of systemic corticosteroids, androgens, or phenytoin.
• Use of pseudo-ephedrine during the study period.
• Use of lipid-lowering drugs or supplements, unless dose stable prior to enrollment (2 months prior for drugs, 2 weeks prior for supplements).
• Use of drugs for regulating hemostasis, other than stable dose aspirin.
• Use of thyroid hormones, except stable-dose replacement therapy for ≥ 2 months prior to enrollment.
• Abnormal laboratory test results of clinical significance, including, but not limited to total cholesterol > 300 mg/dL or triglycerides > 400 mg/dL.
• Females who are pregnant, planning to be pregnant during the study period, lactating, or women of childbearing potential who are not using an approved method of contraception. A woman is considered to be of childbearing potential unless she is post-hysterectomy, post-tubal ligation, or ³ 1 year postmenopausal.
• Recent history of (within past 12 months) or strong potential for alcohol or substance abuse. Alcohol abuse will be defined as > 14 drinks per week (1 drink = 12 oz beer, 4 oz wine, or 1 ½ oz distilled spirits).
• Participation in another clinical study within 30 days prior to screening visit (week -1).
• Individual has a condition the Investigator believes would interfere with the evaluation of the subject or put the subject at undue risk.