When You Are Born Little Catch Up Growth Risks Obesity

Danish researchers working with researchers at the University of Barcelona have been studying girls born smaller than average size. They have been studying their body size, their fat cells, their fat hormones like leptin and adiponectin and watching how they develop from birth, to age 2, 4, 6 and 8. Because prior research shows that reduced fetal growth can actually trigger both early puberty, and early onset of adrenal gland maturity, but small ovaries, they have been trying to then determine what happens to their physiology after that.  In a study published in the July 2011 issue of Fertility and Sterility they published the interesting result of a group of about 30 girls. On the surface being born tiny didn't affect their body type much. The girls grew height, they gained muscle and they developed healthy bones at the same rates. But when they looked more closely they saw physiological changes. The fat hormone leptin began to run higher in girls born small, the fat hormone adiponectin was abnormally low, insulin levels crept up to high levels, they were more likely to have high cholesterol and abnormally low levels of the molecule SHBG. SHBG is important in binding male hormones, so these children were already exhibiting the elevations in male hormones that later in life are associated with menstrual cycle irregularities, hair growth and obesity as well as polycystic ovarian condition. When the girls were born small, they had fewer fat deposits, but as they grew a catch up phenomenon began and the girls gained extra fat and gained this fat extra fast. The fat cells were also bigger, and these enlarged adipocytes, also seen in PCOS, leads to an ease of laying down fat that causes women to be obese as they age. So starting out abnormally small, a medical condition called SGA (small for gestational age) functions as a physiologic trigger that can explain some cases of obesity later in life. These changes are apparent at very young ages in this population of girls. The cure for this is the next step. We don't have answers but using diet, exercise and perhaps in the future medication, to normalize the levels of the fat hormones leptin and adiponectin  may in fact help these girls not be doomed to automatic obesity!