Obesity is a leading world health problem. Excess body weight is a major risk factor for developing type 2 diabetes, cardiovascular disease, dyslipidemia and other co-morbidities that ultimately lead to increased mortality rates. While pharmacotherapies can be employed to better manage obesity, they are hindered by their temporary effectiveness and side effects. This highlights the need for a better understanding of the pathophysiological features of human obesity. Non-human primates (NHPs) provide the most suitable pre-clinical model to investigate human obesity and discover novel therapeutic biomarkers. We have generated a high-fat diet (HFD)-induced NHP model of obesity and pre-diabetes in 34 pigtail macaques (Macaca nemestrina) consisting of 10 HFD males and 10 HFD females with 8 control males and 6 control females. Body composition analysis, glucose tolerance tests in addition to biopsy (muscle, fat and liver) and blood collections were completed at baseline and then every 3 months for 18 months in all animals. Both male and female HFD-fed animals displayed progressional increases in body weight and total body fat mass compared to baseline or lean controls that was due to largely adipocyte hypertrophy. Both HFD-males and HFD-females also demonstrated significantly increased fasting insulin concentrations and insulin area under the curve (AUC) compared to baseline or lean control counterparts determined via intravenous glucose tolerance tests. These findings suggest HFD-induced changes in insulin-sensitivity and development of insulin resistance at the end of the 18-month study. Obesity-induced changes in liver, muscle and fat morphology (steatosis, fibrosis, immune cell infiltration), circulating lipids (triglycerides, total cholesterol, HDL/LDL), metabolic hormones (leptin, adiponectin and C-peptide) and inflammatory markers (TNF-α, IL-1β, IL-6 and IL-10) are simultaneously being investigated using multiplex assays to further validate our model and provide the basis for future biomarker discovery studies.