Springdale Mason Pediatrics

Thin Body Type (Normal Slenderness)


  • Your child looks thin or slender. Their weight is more than 20% below the ideal weight for their height. However, your child is well-nourished, with a normal fat tissue layer (8-12 mm). This is measured by a skinfold calipers.
  • Normal slender children are not actually underweight. They do not need to gain any weight.
  • True underweight children have a low fat tissue measurement. They do need to gain weight.
  • Both normal slender children and underweight children can have a low BMI. (BMI is body mass index.) So, BMI is not helpful in understanding these children.

Call or Return If

  • Your child loses weight
  • Your child does not gain weight for over 6 months
  • You and your child argue about food or mealtime becomes a battleground
  • You think your child needs to be seen
  • You have other questions or concerns


About This Topic

Your child may have a thin body type or build because:

  • Your family is naturally thin. One or both parents are thin, but healthy.
  • Your child has a slender bone structure or frame.
  • The cause is not eating too little. Your child has a normal diet and gets the right amount of calories.

After Care Advice

What You Should Know about Thin Kids:
  • Make sure that your child knows that a thin body type is normal and healthy.
  • Seeing some ribs is healthy. It's called normal slenderness.
  • Thin kids don't need to see their doctor for this or have any special tests.
  • Your child doesn't need to gain more weight.
Avoid Pressure to Eat More:
  • Your child doesn't need more calories.
  • Eating more calories would add fat, not more muscles or bigger bones.
  • A healthy child does not need to over-eat.
  • Trust your child's appetite center in the brain. It will make sure he eats enough calories for normal energy and growth.
  • Avoid any comments or pressure about eating more.
Keep Mealtime Pleasant:
  • Serve well balanced meals and make mealtime pleasant.
  • Talk about fun subjects unrelated to food.
  • Avoid any comments or criticism about how much your child is eating.
  • If your child complains about certain foods, or refuses to eat some foods, see the topic about picky eaters.
Special Foods are Not Needed:
  • Special high calorie drinks or foods are not helpful. Neither are any pills that promise to build muscle or put on weight.
Exercise is Good:
  • Encourage physical activity for everyone.
  • This will improve your child's strength, endurance, muscle mass and confidence.
Bully-proof Against Teasing:
  • Even though children know that they are healthy and look good, some teasing might be expected.
  • Help your child rehearse a reply, such as "Yep, I'm all muscle and bone, lean and mean".

Author: Barton Schmitt MD, FAAP
Copyright 2000-2021 Schmitt Pediatric Guidelines LLC
Disclaimer: This health information is for educational purposes only. You the reader assume full responsibility for how you choose to use it.
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