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Heredity and the path to overweight and obesity
1Physical Activity Sciences Laboratory, Laval University, Sainte-Foy, Québec, Canada.
Medicine and Science in Sports and Exercise
|March 1, 1991
Summary
Genetics significantly influence body weight and composition. Inherited differences in how the body partitions nutrients determine whether individuals gain more fat or lean tissue when overfed.
Area of Science:
- Genetics and Metabolism
- Human Physiology
Background:
- Overweight and obesity present as heterogeneous phenotypes with varying regional fat distribution.
- These conditions are multifactorial, influenced by genetic and non-genetic factors.
Purpose of the Study:
- To investigate the heritability of body composition and energy expenditure components.
- To understand inherited differences in response to overfeeding and nutrient partitioning.
Main Methods:
- Analysis of twin and parent-child data to estimate heritability.
- Examination of fat mass, body fat percentage, resting metabolic rate, thermic response to food, and exercise energy cost.
- Experimental overfeeding studies using identical twins.
Main Results:
- Heritability estimates for fat mass and body fat percentage are approximately 25%.
- Heritability for resting metabolic rate, food's thermic response, and exercise energy cost is around 40%.
- Habitual physical activity also shows significant heritability (~25%).
- Identical twins exhibit inherited differences in weight and body composition changes during overfeeding.
- Nutrient partitioning (fat vs. lean tissue gain) is a key determinant of individual response to overfeeding.
Conclusions:
- Body weight and composition are substantially influenced by genetic factors.
- Individual differences in nutrient partitioning explain varying responses to overfeeding, impacting fat and lean tissue accumulation.