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Plasma leptin responses to fasting in Pima Indians
R E Pratley1, M Nicolson, C Bogardus
1Clinical Diabetes and Nutrition Section, Phoenix Epidemiology and Clinical Research Branch, National Institute of Diabetes and Digestive and Kidney Diseases, Arizona 85016, USA.
The American Journal of Physiology
|October 8, 1997
Summary
Plasma leptin concentrations decrease with short-term energy restriction, such as fasting. These changes in leptin levels are not linked to metabolic rate or key blood markers, suggesting a direct response to energy deficit.
Area of Science:
- Endocrinology
- Metabolism
- Nutritional Science
Background:
- Leptin is crucial for regulating energy balance.
- Factors influencing plasma leptin concentrations are not well understood.
Purpose of the Study:
- To investigate the impact of short-term energy balance changes on plasma leptin concentrations.
- To determine if metabolic rate or specific blood markers correlate with leptin level fluctuations during fasting and feeding.
Main Methods:
- Measured plasma leptin, glucose, insulin, triglyceride, and nonesterified fatty acid concentrations.
- Assessed metabolic rate in 21 healthy Pima Indians.
- Monitored changes following a standard test meal and a subsequent 24-hour fast.
Main Results:
- Plasma leptin decreased by 8% 2-4 hours post-meal and by 37% after a 24-hour fast.
- No significant correlation was found between leptin changes and alterations in glucose, insulin, triglycerides, or nonesterified fatty acids.
- Metabolic rate changes did not correlate with plasma leptin concentration shifts.
Conclusions:
- Plasma leptin concentrations decrease in response to short-term energy restriction (fasting).
- These leptin level changes are independent of glucose, insulin, triglyceride, or nonesterified fatty acid fluctuations.
- The observed decrease in leptin during fasting may serve as a homeostatic mechanism to stimulate food intake and restore energy balance.