This invention provides compounds that are true antagonists of the leptin receptor, in the presence and the absence of native leptin or another leptin receptor binder. These compounds may be used to inhibit leptin receptor activity, promote growth arrest or death of leptin receptor-positive cancer cells, or monitor or detect a leptin receptor-positive cell, in vitro or in vivo. These compounds may also be used to treat a weight-loss nutritional disorder, osteoporosis, rheumatoid arthritis, osteoarthritis, or inflammatory bowel disease. Also included in the invention are methods for detecting leptin receptor-positive cells, for arresting cell growth or killing cancer cells in vivo, for monitoring or detecting a leptin receptor-positive cell in vitro or in vivo, for treating a weight-loss nutritional disorder, for treating osteoporosis, for treating rheumatoid arthritis, for treating osteoarthritis, or for treating inflammatory bowel disease.
