Relationship between a low fructose consumption and insulin resistance

INTERVENTION: Participants are randomized by health care zone to one of two groups. Low‐fructose diet intervention (LFDI) group: Participants are assigned to health centers in the western zone of Tenerife island. They are advised to eat a low‐fructose diet (1000, 1250, 1500, 1750, 2000, 2250, 2500 or 2750 kcal/day). Low‐fructose diets are designed by calculating free and total (free + fructose associated with sucrose) fructose contents in standard diets. Foods with a fructose content in the highest quartile for the amounts corresponding to the standard diet are removed from the standard diet. Standard diet control (SDC) group: Participants are assigned to health centers in the eastern zone of the island. They are advised to eat a standard diet (recommended by the Canary Health Service). The kcal/day in the prescribed diets are calculated as 30% or 40% less than the kcal/day in the participant’s energy requirements for his or her ideal weight according to age, sex and physical activity. Follow up for all participants takes place at 4, 8, 12, 20, 24 and 48 weeks, and involves nutrition counseling and reinforcement, as well as the measure of weight, waist circumference and blood pressure. CONDITION: Insulin resistance ; Nutritional, Metabolic, Endocrine ; Insulin resistance PRIMARY OUTCOME: Insulin resistance is estimated from fasting serum glucose (measured with enzymatic methods) and insulin concentrations (measured with a chemiluminescence immunoassay method) with a computer‐based Homeostasis Model Assessment system (HOMA2‐IR) at baseline, 24 and 48 weeks. SECONDARY OUTCOME: 1. Body mass index is determined using weight and height measurements at baseline, 4, 8, 12, 20, 24 and 48 weeks; 2. Waist circumference is determined using a nonstretchable measuring tape at baseline, 4, 8, 12, 20, 24 and 48 weeks; 3. Total Cholesterol, HDL cholesterol and triglycerides are measured using enzymatic methods at baseline, 24 and 48 weeks. LDL cholesterol is calculated using the Friedewald formula INCLUSION CRITERIA: 1. Age between 29‐66 years 2. BMI between 29 and 40.99 kg/m2