In recent years, the prevalence of overweight and obesity has risen dramatically worldwide affecting individuals of all ages. This increased prevalence has far-reaching consequences on health as individuals with obesity are more likely to develop cardiometabolic diseases, cancer, and other associated comorbidities. However, being extremely complex and heterogeneous, obesity does not present the same way in every individual as some develop diseases while others do not. As such, it is essential to further understand the mechanisms underlying the heterogeneity of obesity which may in part explain the ineffectiveness of obesity interventions in some individuals with obesity. This thesis aims to demonstrate how obesity interventions, age and age of obesity onset affect adipose tissue characteristics and ultimately disease risk. Chapter 1 discusses the impact of dietary fatty acids, exercise, and bariatric surgery on the mechanisms that affect adipose tissue macrophage presence and phenotype in obesity. We find robust evidence suggesting that with or without weight loss, exercise, dietary fatty acids, and bariatric surgery result in immunomodulation via the amelioration of adipose tissue characteristics. Chapter 2 aims to determine whether differences in regional adipose tissue characteristics vary with age and age of obesity onset, and whether these differences are associated with the markers of cardiometabolic health. We show that older adults with childhood-onset obesity are particularly vulnerable to the cardiometabolic effects associated with perturbations in adipose tissue characteristics. Collectively, this thesis demonstrates that indeed obesity interventions, age and age of obesity onset impact adipose tissue homeostasis and health making adipose tissue a potential therapeutic target. However, as age and age of onset should be recognized as risk factors for obesity-associated comorbidities, their impact on the effectiveness of obesity interventions, whether it be exercise, dietary interventions, or bariatric surgery, are unknown. More research is needed to further explore the mechanisms underlying the heterogeneity of obesity and its effects on the efficacy of weight loss interventions.