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Body fat and adipose tissue cellularity in infants: a longitudinal study
Insights
Infant body fat increases significantly from 1 to 18 months, initially due to larger fat cells and later due to more fat cells. By 18 months, fat cell size matches adults, but cell number remains lower.
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.
Abstract:
Body fat, fat cell size, and fat cell number were determined in a longitudinal study on 16 normal-weight infants during the age period 1-18 mo. The methods used included whole-body counting of 40K for determination of body fat and adipose tissue biopsies. A new method of calculation of body fat in infants is presented. No sex differences were found. Body fat expressed as per cent of body weight increased from 16.2% to 28.1%. From 1 to 12 mo of age the expansion of body fat was explained by and increase in fat cell size, while in the age period 12-18 mo it was mainly due to an increase in fat cell number. At 18 mo lthe fat cell size was the same as in 8-yr-old girls and 22-yr-old women (normal-weight females previously studied). The fat cell number at 18 mo, however, was far below the number at 8 yr of age, as well as the still higher number of the 22-yr-old women.