Calorie Restriction, Leptin and Metabolic Adaptation

geekyjock76

Although calorie restriction is necessary for fat loss, there are many people who establish and prolong a deficit to the point they get full eating a fraction of the calories they once were able to consume.

Hunger should not be used as the primary measurement tool to ensure you are providing yourself with adequate energy when on calorie restriction. When I was an athlete growing up, I was told not to eat when hungry but rather to meet the energy needs I placed on my body. This research study further establishes leptin's role in metabolic adaptation during calorie restriction and its potential impact on weight loss and weight recovery.

The Fall in Leptin Concentration Is a Major Determinant of the Metabolic Adaptation Induced by Caloric Restriction Independently of the Changes in Leptin Circadian Rhythms

Abstract

Context: Leptin is involved in the hormonal regulation of the reproductive, somatotropic, thyroid, and autonomic axes and ultimately in the regulation of energy balance. In parallel to the metabolic adaptation observed in response to caloric restriction (CR), plasma leptin concentrations are substantially decreased, suggesting a role for this hormone in the drop in energy expenditure beyond that predicted by the changes in body composition (metabolic adaptation).

Aim: The aim of the study was to explore the changes in 24-h leptin circadian rhythm in response to CR and to investigate the relationship between these changes and metabolic adaptation.

Design: In a randomized, controlled trial (Comprehensive Assessment of Long-Term Effects of Reducing Intake of Energy), 48 subjects were assigned to a control group or one of three CR groups for 6 months. Leptin concentration was assessed every 30 min for 24 h, and leptin circadian variations were fitted by Cosinor analysis. Sedentary energy expenditure and urinary catecholamine excretion were measured for 24 h in a metabolic chamber.

Results: Six months of CR decreased body weight by −11.4 ± 0.6% (mean ± SEM; P < 0.001). Mean 24-h circulating leptin concentration decreased by −44 ± 3% (P < 0.001), whereas leptin diurnal amplitude slightly increased over the 6 months of CR. CR caused a metabolic adaptation of −126 ± 25 kcal/d (P <0.001) and a significant decrease in urinary norepinephrine (−13 ± 3%) and T3 concentrations (10 ± 2%). The metabolic adaptation was significantly and independently related to the changes in 24-h leptin (r2 = 0 .22, P < 0.01) but not to the changes in leptin amplitude.

Conclusion: Our results confirm an important role for leptin as an independent determinant of the metabolic adaptation in response to CR.

The entire full text is here:

http://jcem.endojournals.org/content/96/9/E1512.full?sid=c2c187ec-5445-48ad-9291-be95019f6a68