Body fat and adipose tissue cellularity in infants: a longitudinal study

Area of Science:

• Pediatrics
• Human Physiology
• Body Composition

Background:

• Understanding infant body composition changes is crucial for assessing growth and long-term health.
• Fat cell dynamics (size and number) play a key role in regulating body fat accumulation.

Purpose of the Study:

• To longitudinally track changes in body fat, fat cell size, and fat cell number in normal-weight infants from 1 to 18 months of age.
• To present a novel calculation method for infant body fat determination.

Main Methods:

• Longitudinal study involving 16 normal-weight infants.
• Whole-body counting of 40K to determine body fat.
• Adipose tissue biopsies to assess fat cell size and number.
• Development of a new body fat calculation method for infants.

Main Results:

• Body fat percentage increased from 16.2% to 28.1% between 1 and 18 months.
• From 1-12 months, body fat expansion was primarily driven by an increase in fat cell size.
• From 12-18 months, body fat expansion was mainly due to an increase in fat cell number.
• No significant sex differences were observed in body fat parameters.

Conclusions:

• Infant body fat accretion involves distinct phases of fat cell enlargement followed by proliferation.
• By 18 months, infant fat cell size reaches adult levels, but fat cell number remains significantly lower than in older children and adults.
• The findings highlight critical developmental windows for adipogenesis in early life.