Use of a Soy-based Meal Replacement Weight Loss Intervention to Impact Ectopic Fat (SILVER)

Use of a Soy-based Meal Replacement Weight Loss Intervention to Impact Ectopic Fat and Associated Cardio-metabolic Risk in Obese, Older Adults: A Feasibility Study

The main objectives of this study are to collect pilot data to assess feasibility (accrual, retention, compliance), to estimate the variability of outcome measures, and to obtain preliminary estimates of treatment efficacy based on group differences in body composition (decreases in ectopic fat stores while maintaining lean mass), cardio-metabolic risk factors including glucoregulatory function (glucose, insulin), inflammation (C-reactive protein, IL-6), blood pressure and lipids (HDL, LDL, TC, TG), and measures of physical function and muscle strength. While this is just a pilot study, randomization will be used so that the investigators can obtain a realistic estimate of accrual (which is often less in a randomized trial) and an unbiased estimate of treatment efficacy. The investigators will accomplish these objectives by conducting a 2-arm, 3-month randomized, clinical trial in 24 older (60-79), abdominally obese (BMI ≥30 kg/m2 and waist circumference ≥ 102 cm and ≥ 88 cm in men and women, respectively) men and women. Participants will be randomized to a soy-based or animal-based, 3-month, hypocaloric dietary intervention to achieve our specific aims: Primary Aim: To determine our ability to recruit and retain older, obese adults to a 3 month soy-based meal replacement weight loss intervention and assess the study participant's ability to adhere to the intervention protocol (weight, compliance logs, serum isoflavones). Secondary Aims: To estimate the variability of and obtain preliminary estimates of the effect of the soy-based meal replacement on measures of body composition, including abdominal (total, subcutaneous and visceral fat), liver, and pericardial fat; anthropometrics (body weight, waist/hip circumference); and whole body fat and lean mass. To estimate the variability of and obtain preliminary estimates of the effect of the soy-based meal replacement on biomarkers of cardiometabolic risk including glucoregulatory function (glucose, insulin), inflammation (C-reactive protein, IL-6), blood pressure and lipids (HDL, LDL, TC, TG). To estimate the variability of and obtain preliminary estimates of the effect of the soy-based meal replacement on physical function (short physical performance battery, 400-m walk) and muscle strength (grip and knee extensor strength) and size (CT thigh muscle). To document any adverse events associated with the soy-based meal replacement.

A total of 4 meal replacement (MR)products per participant per day will be used. Approximately 2/3rd of the Medifast® MR product line is soy protein-based (i.e. at least 7 g of total protein coming from soy) with the remaining 1/3rd of items deriving total protein content from animal sources (whey and egg). The soy used in Medifast products is Solae SUPRO® water-washed soy protein isolate. Depending on seasonal variations, soy MR products contain approximately 1.5-3.0 milligrams of soy isoflavones for every 1 gram of soy protein. Thus, participants in the soy treatment arm will consume at least 28 g/soy protein and 42-108 mg/isoflavones per day.

A total of 4 meal replacement (MR)products per participant per day will be used. Approximately 2/3rd of the Medifast® MR product line is soy protein-based (i.e. at least 7 g of total protein coming from soy) with the remaining 1/3rd of items deriving total protein content from animal sources (whey and egg). This group will receive the non soy supplements.

To determine our ability to recruit and retain older, obese adults to a 3 month soy-based meal replacement weight loss intervention and assess the study participant's ability to adhere to the intervention protocol (weight, compliance logs, serum isoflavones).

To estimate the variability of and obtain preliminary estimates of the effect of the soy-based meal replacement on measures of body composition, including abdominal (total, subcutaneous and visceral fat), liver, and pericardial fat; anthropometrics (body weight, waist/hip circumference); and whole body fat and lean mass.

To estimate the variability of and obtain preliminary estimates of the effect of the soy-based meal replacement on biomarkers of cardiometabolic risk including glucoregulatory function (glucose, insulin), inflammation (C-reactive protein, IL-6), blood pressure and lipids (HDL, LDL, TC, TG).

To estimate the variability of and obtain preliminary estimates of the effect of the soy-based meal replacement on physical function (short physical performance battery, 400-m walk) and muscle strength (grip and knee extensor strength) and size (CT thigh muscle).

Inclusion Criteria: Age = 60-79 years old BMI ≥ 27 kg/m2 Waist Circumference= men ≥ 102 cm; women ≥ 88 cm Non-impaired cognitive function (MMSE > 21) Willing to provide informed consent No contraindications for participation in weight loss Able to provide own transportation to study visits and intervention Willing to consume meal replacement products (i.e. no soy/dairy allergies, product found to be palatable) Not involved in any other research study Exclusion Criteria: Weight loss or gain (±5%) in past 6 months Body mass > 136 kg (DXA limit) Regular smoker (> 1 cigarette/day) within past year History of alcohol or substance abuse or dependence within the past 2 years (DSM IV criteria) Insulin-dependent or uncontrolled diabetes (FPG ≥ 126 mg/dL) Self-reported hepatitis Abnormal kidney function (creatinine > 2.0) Abnormal liver blood test (AST, ALT, total bilirubin- greater than twice the upper limit of normal; albumin - less than 2.0) Unstable angina MI, PCI or cardiac surgery < 3 month ago Uncontrolled blood pressure (> 160/90 mmHg) Chronic pulmonary disease (> mild or recent exacerbations) Thyroid disease Known significant hematological disease (including HBG < 11) Active known cancer requiring treatment in past year (except non-melanoma skin cancers) Life expectancy < 2 years Regular use of any medications that could influence study variables (growth/steroid hormones, including estrogen replacements, thiazolidinediones, statins, regular anti-inflammatory medications, weight loss medications, etc.)