Many guys and girls are skinny until they start to go through puberty. The changes that come with puberty include weight gain and, in guys, broader shoulders and increased muscle mass.
As a child's entire body size increases, the amount of body fat stays relatively stable, giving her a thinner look. Also during this stage of life, a child's legs are longer in proportion to the body than they were before.
Puberty. Hormones released during this time often cause boys to gain muscle and girls to experience an increase in body fat. These changes are normal, but they may make you feel like you're overweight, even if you're not.
Puberty Weight Gain and Growth
When girls get taller, they tend to lose that belly fat and may thin out over time. During this time, you will notice body weight redistribution and the addition of fat tissue–to the rear, hips, breasts, backs of arms, and thighs.
The averages for 12-year-olds are 89 pounds, for males, and 92 pounds, for females. However, beyond biological sex, many other factors influence someone's weight at this age, including their height, body composition, the onset of puberty, environmental factors, and underlying health issues.
Get Active
The more exercise you get, the faster the weight will come off. You can also use weight training to help you gain lean muscle mass that will make your body burn more calories. Start with body weight exercises like pushups, pullups, squats, dips and lunges, and add weight gradually as you get stronger.
According to the Centers for Disease Control and Prevention (CDC), most 13-year-old girls weigh around 76–148 pounds (lb) and most 13-year-old boys weigh between 75 and 145 lb, but this can vary widely. The average weight of a 13-year-old will depend on a number of factors.
Noticeable weight gain may occur prior to a growth spurt as excess fat helps promote growth. As a child goes through puberty, their stores of body fat may change.
Your child will experience many changes in their body during this time. For girls, puberty usually occurs between ages 10 to 14, and for boys, between ages 12 to 16.
Puberty – Increased hormones in a child's body during puberty (between the ages of 10 and 14 for girls and between the ages of 12 and 16 for boys) leads to growth and dramatic slimming of “baby fat” areas.
It is usually easier to lose weight as a teenager than as an adult due in part to metabolic differences. It is beneficial to achieve and maintain a healthy weight as a teen and carry it forward into adulthood.
During the middle-school years, a major growth spurt usually occurs, which can be very confusing to both kids and parents. Appetite soars in preparation of a growth spurt. Consequently, many tweens and teens get heavier before they grow taller!
Men often gain weight until about age 55, and then begin to lose weight later in life. This may be related to a drop in the male sex hormone testosterone. Women usually gain weight until age 65, and then begin to lose weight.
Body shape – Another sign of puberty in girls is changing body shape, particularly extra fat in the belly area (some call it “baby fat”). Weight gain can cause anxiety for girls. This is part of normal development, and her body will redistribute the fat from the stomach and waist to the breast and hips.
A high metabolism means a person burns more calories at rest and during activity. Therefore, there is no piling up of fats or weight gain. A very high metabolism rate can be unhealthy as the person is unable to maintain a healthy weight.
“Obesity incidence starts increasing in one's twenties and peaks at 40 to 59, and then decreases slightly after age 60,” says Craig Primack, MD, an obesity medicine physician at the Scottsdale Weight Loss Center in Arizona.
More significant weight gain is normal during the preadolescent ages of roughly 9 to 12 and adolescence – as a child matures into a young adult. It's not unusual for the body to store fat during this time as it prepares for the rapid growth and changes associated with puberty.
Even though a 13 year old who is 70 kg is considered to be overweight as they suggest you should be weighing more like 50 to 60 plus kg, you are a growing teenager (providing that you are still growing, I'm only saying this because when I was your age I stopped growing unfortunately for me).
Remember, some children are naturally thin. This is part of their constitution. Some kids may be thin due to suboptimal or inadequate nutrition.
Puberty – Increased hormones in a child's body during puberty (between the ages of 10 and 14 for girls and between the ages of 12 and 16 for boys) leads to growth and possible expansion of “baby fat” areas. This typically takes place in girls' belly, breast area and hips. Boys' shoulders will get broader.
But if they do need to slim down, experts say teens shouldn't drop more than 2 pounds a week. Talk with your child to get their buy-in. They have to be on board and involved with any plan to lose weight.
You bet! Done properly, it offers many benefits to young athletes. Strength training is even a good idea for kids who simply want to look and feel better. In fact, this form of exercise might put your child on a lifetime path to better health and fitness.
So according to a bmi chart your suggested weight range is 112 - 151Lbs. But many factors such as bone mass, muscle mass and fat percentage are important too. If you are a lot over or under this weight range, consider changing your diet and/or exercise. You are still young so don't push it.