Jeffrey M. Friedman (born July 20, 1954) is a molecular geneticist at New York City's Rockefeller University and an Investigator of the Howard Hughes Medical Institute.

His research on various aspects of obesity received national attention in late 1994, when it was announced that he and his colleagues had isolated the mouse ob gene and its human homologue.

They subsequently found that injections of the encoded protein, leptin, decreases body weight of mice by reducing food intake and increasing energy expenditure.

Friedman was born in Orlando, Florida on July 20, 1954, and grew up in North Woodmere, New York, graduating from Hewlett High School in the Class of 1971.

Working with a special strain of mice, he set out to identify the hormone that normal animals use to control their appetite - a molecule that was missing in the plump rodents.

[citation needed] With the identification of leptin and its receptors by Friedman's laboratory, two of the molecular components of a system that maintains constant weight were identified.

Leptin is a hormone secreted by the adipose (fat) tissue in proportion to its mass that in turn modulates food intake relative to energy expenditure.

[citation needed] In studies of obese mice, Friedman has found that leptin actually restructures the brain, rewiring the neural circuit that controls feeding.