Obesity is defined as an accumulation of excessive amounts of adipose tissue in the body.1
Adipose tissue does more than simply store excess energy; it is also an active endocrine organ.
Adipocytes (fat cells) secrete a variety of hormones, cytokines, and other protein factors—collectively called adipokines—that biologically influence the rest of the body.
Studies show that obesity is associated with a state of chronic, low-grade inflammation,2 a condition that predisposes pets to diseases such as osteoarthritis and diabetes mellitus.
Adipose tissue produces more than 100 adipokines that have systemic impacts ranging from appetite regulation to blood pressure. These include pro-inflammatory cytokines such as tumor necrosis factor-α (TNF-α), interleukin-6, and C-reactive protein.3
Secretion of adipokines is altered in obesity. In human studies on obesity, blood levels of inflammatory cytokines are systemically raised.4 Similarly, research by Purina, as well as others, has shown that obese dogs and cats have increased concentrations of inflammatory adipokines when compared to lean animals.5-10
Since adipose tissue—or, more specifically, white adipose tissue—is a source for these inflammatory compounds, elevated levels of inflammatory adipokines appear to be a link between obesity and many weight-related diseases.3,11
Insulin resistance in obesity, for example, is linked with elevated levels of TNF-α which is a cytokine that blocks activation of insulin receptors.12-15
Research also shows that obesity is associated with greater production of free radicals, which leads to increased oxidative stress. Oxidative stress contributes to tissue damage that can play a role in the development of many diseases.16,17
Many of these adverse effects can be reduced or reversed with weight loss.5,7,13, 18-20