A Trial of the Ideal Protein System Versus Low Fat Diet for Weight Loss

Restricting total calorie intake is emphasized in the 2013 American Heart Association/ American College of Cardiology/ The Obesity Society Guideline (AHA/ACC/TOS) for the Management of Overweight and Obesity in Adults for its effectiveness at reducing body weight and decreasing cardiometabolic risk factors. An implication of this focus on total quantity of calories consumed is that macronutrient composition of dietary intake and its effects on the hormonal milieu that regulates adipose accumulation in the human body do not play a significant role in weight loss. Such recommendations and the results of limited previous studies have led to the advice that all weight loss diets regardless of macronutrient composition will produce the same degree of weight loss if adherence to the diet is similar. In contrast, our previous studies have shown that despite comparable adherence to dietary goals, participants losing weight on a moderately carbohydrate-restricted, adequate protein regimen have improved cardiometabolic indicators as compared to those restricting fat. The RENEWAL trial will provide unique data on the efficacy of the Ideal Protein method (moderate carbohydrate restriction and adequate protein) for weight loss and improvement in cardiometabolic risk factors. The interventions will include a significant proportion of African-Americans, a group with very high rates of obesity which is often under-represented in trials examining the effects of weight loss diets. Findings from this trial may offer new evidence for the recommendation of specific macronutrient and behavioral approaches to the reduction of cardiometabolic risk factors.

Inclusion criteria

• All participants will be obese. Obesity will be defined as BMI ≥ 30 kg/m2 at the baseline study visit. An upper limit of BMI will be set at 49 kg/m2 to include a wide range of obese men and women with a reasonable probability of losing weight in the context of a dietary behavioral intervention.
• Participants must have at least one co-morbid condition that increases risk of cardiovascular disease (history of CVD, type II diabetes mellitus, fasting plasma glucose>100 mg/dL, metabolic syndrome as defined by ATP III criteria, hypertension, hyperlipidemia, WC>40 in among men or >35 in among women).
• All potential participants must be willing and able to provide informed consent.

Exclusion criteria

• History of any bariatric surgery, including gastric banding, Roux-en-Y and duodenal switch with biliopancreatic diversion procedures, vertical banded gastroplasty, etc.
• Currently on a diet or using prescription weight loss medications, and/or experienced weight loss >15 pounds within 6 months of study entry.
• Regular use of alcohol >3 beverages per day or 21 beverages per week (1 standard beverage = 350 mL of 5% alcohol beer, or 150 mL of 12% wine, or 45 mL of 80-proof distilled spirits), amphetamines, cocaine, heroin, or marijuana over past 6 months.
• Past or present history of eating disorder (including anorexia, bulimia or binge eating disorder) or severe/untreated psychiatric illness which may affect participation in study interventions.
• Strict dietary concerns (e.g., vegetarian or kosher diet, significant nut or multiple food allergies). This is an exclusion because participant may not be able to fully participate in the intervention.
• For women, current pregnancy or breastfeeding or plans to become pregnant during the study period. This is an exclusion because weight loss is contraindicated during pregnancy.
• Plans to move out of the study area (>1 hour from study site) or difficulty to come to the study site. This is an exclusion because these conditions may interfere with the ability to fully participate in and complete the study.
• Participation of another household member in the study; employees or persons living with employees of the study. This is an exclusion because randomization of more than one participant in a household to differing diets may cause conflict within a household and limit engagement in the intervention. Employees of the study are excluded due to potential conflicts of interest and knowledge of study assignments.
• Participation in other lifestyle intervention trials currently. This is an exclusion because interference with ability to determine whether study interventions are responsible for outcomes.
• Medical condition in which a carbohydrate restricted diet may not be advised (eg. severe renal impairment, osteoporosis, untreated thyroid disease, frequent gout attacks, Type I diabetes). This is an exclusion because participant may not be able to fully participate in the intervention.
• Hospitalization for a CVD event such as myocardial infarction, stroke, TIA, coronary revascularization, heart failure, peripheral artery disease, or unstable angina within the last 6 weeks or unstable coronary artery disease. Major new medical illness including renal disease requiring dialysis, a life-threatening illness with life expectancy less than six months, or cancer requiring chemotherapy or radiation treatment in the previous two years. [NOTE: potential participants may still qualify if they have had treatment for an early stage cancer in the past two years and the prognosis is excellent.] This is an exclusion because these conditions may interfere with the ability to fully participate in and complete the study.
• MMSE score < 23 or dementia. This is an exclusion because it may interfere with the ability to fully participate in the study.
• Non-English speaking, a visual impairment or a hearing impairment that interferes with study participation. This is an exclusion criterion because these potential participants may not be able to participate fully in the intervention.
• In addition to the above criteria, investigator discretion will be used to determine if the trial is unsafe or not a good fit for the potential participant.