06 December 2008

Rosenbaum and his team reported similar results several years ago in a study published in the Journal of Clinical Endocrinology and Metabolism, where a low-dose course of "replacement" leptin reversed some of the metabolic changes that occur during weight loss.

Four subjects (2 men and 2 women) join the study as volunteers. They fed with 800 calories/day until they'd lost 10% of their initial weight. This led to the decline the leptin level and thyroid hormone concentrations, along with a reduction in the metabolic rate.

For the next five weeks, subjects received low-dose leptin injections twice/day to bring leptin back to pre-diet levels. These "replacement doses" of leptin reversed the drop in energy expenditure and thyroid hormone levels. The participants also continued to lose fat while preserving muscle tissue.

It looks like a drop in leptin production acts as a signal of negative energy balance (you're burning more calories than you're taking in) and low energy reserves, rather than indicating a positive energy balance and increased energy reserves.

The primary functional role of leptin is apparently to defend, not reduce body fat by increasing food seeking and decreasing energy expenditure when fat stores are insufficient. Physiological responses to concentrations of leptin below and above this threshold are very asymmetrical : decreased concentrations of leptin trigger full-strength counter-regulation to what is "perceived" as a threat to survival; concentrations of leptin above the threshold signaling "sufficient" or excess fat stores are not responded to vigorously, or at all.

Your body will fight harder against losing fat than it will against gaining fat. That's why most people find it a whole lot easier to get fat than they do to get lean.

So, don’t get wrong if some have referred to leptin as an "anti-obesity hormone," that totally wrong. It's more accurate to label it as an "anti-starvation" hormone that tells your brain what to do when energy is in short supply.

See Leptin level, Obesity, and Weight loss-What is the Connection? for more information.
See Leptin for Weight Loss for more information.
See Is it Effective Taking Leptin as Weight Loss Pill? for more information.


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