The Effects of Formula Diet on Body Weight, Body Composition, and Biomarkers for Disease Compared to a Standard Diet

It is hypothesized that the use of a partial supplement diet, which includes the use of meal replacements, will result in significantly greater weight loss after three and six months compared to an isocaloric diet that does not include supplements. It is also hypothesized that the partial supplement diet will result in larger improvements in body composition, disease biomarkers, and health parameters (blood pressure, lipids) compared to the non-supplement diet. Finally, it is hypothesized that subjective ratings of satiety will be significantly higher, and ratings of hunger lower, in the group consuming a partial supplement diet.

In recent decades, the prevalence of overweight and obesity has increased dramatically in developed countries. Obesity is associated with diseases such as diabetes, cardiovascular disease, hypertension, and certain cancers. Modest amounts of weight loss (e.g., 5% to 10% of initial body weight) significantly improve health and improve disease status. Recent evidence suggests that the use of supplements or meal replacements promotes greater weight loss than isocaloric food-based diets. In addition, diets that are high in protein are associated with greater ratings of satiety and reduced food intake, as well as greater weight loss, compared to lower protein diets.

The purpose of the proposed study is to test the effect of a partial supplement diet on body weight, body composition, and biomarkers for disease compared to an isocaloric diet that consists of a traditional food-based meal plan. Overweight and obese (BMI 25 to 35) participants will participate in this six-month study. The primary outcome variable is body weight loss and the secondary outcome variables include body composition, blood pressure, lipids, and subjective ratings of satiety.

Eligibility Criteria:
Inclusion Criteria:

* Male or female gender; of all ethnic backgrounds.
* Healthy person who has not been diagnosed with diabetes, cardiovascular illness, renal, hepatic or other chronic diseases
* \> 17 years and \< 66 years of age
* Body mass index (BMI; kg/m2) between 25 and 35
* For females with the potential to bear children, they meet one of the following criteria:

  * They are willing to use an acceptable method of birth control (e.g., oral contraceptive tablets, implanted contraceptive hormones, Depo-Provera® contraceptive injections, intrauterine devices, prophylactic condoms with spermicide, contraceptive diaphragms with spermicide, cervical caps with spermicide), or are in a monogamous relationship with a partner who has had a vasectomy.
  * They are sexually abstinent and intend to continue this practice, at least for the duration of the study.

Exclusion Criteria:

* \> 65 years and \< 18 years of age
* Regular use of medications other than birth control, vitamins or hormone replacement therapy
* Diabetes mellitus (fasting blood sugar \[FBS\] \> 126); persons with impaired glucose tolerance (FBS 100-125) may be admitted to the study.
* Use of tobacco products
* Depression or mental illness requiring treatment or medication within the last six months
* For women, pregnancy, breast feeding, postpartum \< 6 months, planning a pregnancy during the study, or are not using an acceptable method of contraception
* Use of medications or herbal supplements that affect appetite or body weight for the previous three months
* Patients requiring restriction of protein intake
* Impaired kidney function (creatinine \> 1.5) or liver function (liver enzymes \> 3 times the upper limits of normal)