Effect of Enriched Meal Replacements Protein on Weight Loss in Adults With Metabolic Syndrome

Our study was a randomised clinical trial with a 6-month follow-up in Mexican adult men and women (20-65 years) with Metabolic Syndrome (MS). The individuals were invited to participate from posters and social network advertising. The study was conducted in two Mexican clinics (Mexico City and Cuernavaca) for obesity and metabolic disorders, used by the Mexican National Institute of Public Health (INSP) as recruitment centers. The sample size was calculated using a formula that compares two means, an alpha of 0.05 and a power of 95%. Based on these calculations, we established a baseline sample of 118 adults.

For the diagnosis of MS, we used the classification from the International Diabetes Federation (IDF), and therefore participants were required to have three or more of the following criteria: a) waist circumference ≥90 cm in men and ≥80 cm in women, b) triglycerides ≥150 mg/dL, c) high density lipoprotein (HDL-cholesterol) <40 mg/dL in men and <50 mg/dL in women, d) blood pressure ≥130/85 mmHg; and e) fasting glucose ≥100 mg/dL. Exclusion criteria included bariatric surgery for weight loss, smoking, use of alcohol or drugs, psychiatric disorders, anti-obesity medication, soy protein intolerance, women not using birth control methods, and not pregnant or lactating, and body weight gain or loss greater than two percent three months prior to the start of the study. To achieve the baseline sample of 118 adults, 150 patients were screened; however, 32 were excluded because they did not meet the criteria.

During screening, individuals interested in participating received an explanation of the study design and were given sufficient time to consider inclusion in the clinical trial and complete the form for informed consent. On the same day as consent, doctors wrote down medical history; nutritionists conducted anthropometry (weight, height, and waist circumference); and nurses measured blood pressure and withdrew venous blood for determination of glucose, triglycerides, and HDL-cholesterol.

After the medical evaluation and nutritional status, we provided meal replacements enriched with soy protein that were consumed during the following two days, testing soy protein tolerance. Each clinic supervisor enrolled participants, and the study coordinator conducted the randomization sequencing and assigned participants to interventions.

After being randomly assigned to one of two groups, the control group received a diet with a lower protein content (0.8gr/kg body weight), and the intervention group received a diet with higher protein content (1.34gr/kg body weight). Both diets had equal amount of calories, were equivalent in the type of carbohydrate, and had a caloric restriction of 500 calories less than the resting metabolic rate (RMR) based on the Harris-Benedict´s formula. The overall study design is shown in Figure 1.