Chuck "Kali Muscle" Kirkendall, Jr. writes in XCON TO ICON - The Kali Muscle Story
[referring to the summer before his first year of high school, 9th grade, at Castlemont High School] Luckly I made the team but I barely made the cut because of weighing in at 99 lbs. Coach Green said I would have to gain 1 pound to make the team, so all summer I ate a lot of McDonalds and the day of the weigh in I weighed 101 lbs.
...
[end of 10th grade] I was around 165 pounds
...
[at the end of July between Sophomore and Junior years of high school] I now weighed 175 pounds
...
I had reached a weight of around 185 pounds, which made me look like I weighed around 200 pounds to everyone else. My body had definitely matured since being the scrawny, 100 pound kid I used to be in ninth grade, the one that didn't play but one down his entire freshman year of football
So it was more like age 14 that he was 99 pounds (born 1975, graduated from high school 1993). His current height is 5'9", so 100 pounds at age 14 is entirely reasonable.