Sensitivity to overfeeding: the Quebec experiment with identical twins

Area of Science:

• Metabolic research
• Human genetics
• Obesity research

Background:

• Individual responses to caloric surplus vary significantly.
• Understanding the genetic basis of metabolic adaptation is crucial for personalized health strategies.

Purpose of the Study:

• To investigate the role of genotype in the body's adaptation to short-term overfeeding.
• To determine if genetic factors influence changes in body composition and energy expenditure.

Main Methods:

• Six pairs of monozygotic twins underwent a 22-day period of 1000 kcal/day energy surplus.
• Measurements included body composition, resting metabolic rate, and energy cost of exercise.
• Assessed fat cell lipolysis and adipose tissue lipoprotein lipase activity.

Main Results:

• Significant within-pair resemblance in fat mass and fat-free mass gains, indicating a strong genetic influence.
• Genetically determined patterns observed in resting metabolic rate, thermic effect of a meal, and exercise energy cost.
• Genotype-overfeeding interactions affected serum triglycerides and HDL-cholesterol levels.

Conclusions:

• Genotype plays a substantial role in determining individual responses to overfeeding, particularly in body composition changes.
• Energy expenditure components are key mediators of genotype-specific adaptations to caloric surplus.
• Genetic predisposition significantly influences metabolic and body composition adjustments to overfeeding.