of factors that may promote cachexia in cancer. Tumor-derived molecules such as lipid mobilizing factor, proteolysis-inducing factor, and mitochondrial uncoupling proteins may induce protein degradation and contribute to cachexia. Uncontrolled inflammation in cachexia can lead to an elevated resting metabolic rate, further increasing the demands for protein and energy sources. There is also evidence of alteration in feeding control loops in cachexia. High levels of leptin, a hormone secreted by adipocytes, block the release of neuropeptide Y, which is the most potent feeding-stimulatory peptide in the hypothalamic orexigenic network, leading to decreased energy intake despite the high metabolic demand for nutrients. Diagnosis Diagnostic guidelines and criteria have only recently been proposed despite the prevalence of cachexia and varying criteria, the primary features of cachexia include progressive depletion of muscle and fat mass, reduced food intake, abnormal metabolism of carbohydrate, protein, and fat, reduced quality of life, and increased physical impairment. Historically, body weight changes were used as the primary metrics of cachexia, including low body mass index and involuntary weight loss of more than 10%. Using weight alone is limited by the presence of edema, tumor mass and the high prevalence of obesity in the general population. Weight-based criteria do not take into account changes in body composition, especially loss of lean body mass. In the attempt to include a broader evaluation of the burden of cachexia, diagnostic criteria using assessments of laboratory metrics and symptoms in addition to weight have been proposed. The criteria included weight loss of at least 5% in 12 months or low body mass index (less than 22 kg/m2) with at least three of the following features: decreased muscle strength, fatigue, anorexia, low fat‐free mass index, or abnormal biochemistry (increased inflammatory markers, anemia, low serum albumin). In cancer patients, cachexia is diagnosed from unintended weight loss of more than 5%. For cancer patients with a body mass index of less than 20 kg/m2, cachexia is diagnosed after the unintended weight loss of more than 2%. Additionally, it can be diagnosed through sarcopenia, or loss of skeletal muscle mass. Laboratory markers are used in evaluation of people with cachexia, including albumin, prealbumin, C-reactive protein, or hemoglobin. However, laboratory metrics and cut-off values are not standardized across different diagnostic criteria. Acute phase reactants (IL-6, IL-1b, tumor necrosis factor-a, IL-8, interferon-g) are sometimes measured but correlate poorly with outcomes. There are no biomarkers to identify people with cancer