Abstract Obesity is defined as the accumulation of adipose tissue, overweight and obesity are defined on the basis of body mass index and this is accompanied by an increased prevalence of comorbidities as type 2 diabetes, cardiovascular and metabolic disease in the population. The research related to obesity, overweight and metabolic syndrome use animal models, rats and mice generally, these animal models use hypercaloric diets with fat content ranging from 12% to 49% in fat, in addition to the high-calorie diet with a high content of fats, solutions with a varied concentration of sweeteners up to 30% are used (fructose, glucose, galactose), with duration of treatment with diet and sweetened drinking water that goes from 3 to 5 months, also find genetically manipulated animals, but in most cases they are costly and inaccessible models for researchers. In 1959 William M. S. Russell and Rex L. Burch published the principle of the 3 R’s for research (Replace, Reduce, and Refine), in this sense, we proposed to refine the model and to evaluate the intragastric administration of fructose syrup (80%), the results were rats with phenotype metabolically healthy but obesity in eight weeks with adiposity index of 11.4 for fructose syrup group vs 8.0 of water control group (fructose solution as drinking water) and 6.2 for control group, with elevated blood glucose at the fourth and seventh week of treatment.
Keyword: Obesity, 3R’s principle, Glucose Oral Tolerance, Body Mass Index, Adiposity Index.