A new study offers insight into why
it's easier to lose weight than to keep it off for good.
Body weight is regulated by metabolic, neuroendocrine,
and autonomic systems, which work together to restore
fat mass in people who've lost weight, the study authors
concluded. That's because the body interprets reductions
in weight as a deficiency in the hormone leptin.
These mechanisms explain why more than 85 percent of
obese people who've lost weight eventually regain those
pounds, the Columbia University researchers said.
They tested this theory by giving "replacement" doses
of leptin to obese people and to lean people who'd just
lost weight. The leptin doses reversed most of the metabolic,
neuroendocrine and autonomic changes that occur in an
effort to counter reduced body weight.
The study appears in the Dec. 1 issue of the Journal
of Clinical Investigation.
The findings suggest that drugs that target the leptin
signaling pathway may help prevent people from regaining
weight after they've lost it, the scientists said.
A study published in November found that in obese rats,
the receptor for leptin -- which makes fat burn up --
disappears from fat cells. This means that leptin can't
act on the fat cells, the University of Texas Southwestern
Medical Center at Dallas researchers said.
