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What is a Normal Weight for an 18-Year Old?


18 years old is a time of change and transition into adulthood. It is a time of growth and development physically, emotionally, and mentally. Everyone’s development happens at a different pace, so your body might still be changing. You may wonder what a healthy weight is for you to settle into.

A normal weight for an 18-Year old is defined as having a Body Mass Index (BMI) between the 5th and 85th percentiles on the Center of Disease Control and Prevention’s (CDC) growth charts. For example, for a 5 foot 9 inch tall 18-year old boy, a weight between 119 to 174 pounds (54 to 79 kilograms) is considered normal healthy. For a 5 foot 4 inch tall 18-year old girl, a weight between 102 to 148 pounds (46 to 67 kilograms) is considered healthy. However, evaluating an 18-year old’s overall health status is a bit more complex than that. Health is defined by much more than BMI. All other factors should be taken into consideration when determining health status.

Read more to find out what factors help determine a healthy weight for a 18-year old and tips to help 18-year olds be the healthiest they can be.

What is Overweight for an 18-Year Old?

The CDC growth charts classify an 18-year old as being “overweight” if they are above the 85th percentile. If they are above the 95th percentile, they are classified as “obese.” However, these are just classifications to be used as a screening tool, and do not necessarily correlate perfectly with health status.

If an 18-year old has a lot of muscle mass, they will also have a higher BMI. It is important to look at body composition as well as overall health habits to determine if an overweight or obese classification is actually unhealthy.

You can calculate and estimate your own BMI (see next section). Height, weight, age, sex, etc. are taken into account.

According to the CDC growth charts, an 18-year old female at 5 foot 4 inches tall is considered overweight above 149 pounds (or 68 kilograms). An 18-year old male at 5 foot 9 inches tall is considered overweight above 175 pounds (or 80 kilograms). Remember that different heights and ages are assessed differently.

If you (or your teenager) falls into the “overweight” category, don’t stress. Talk to your healthcare provider. Patterns over time are more important than one point on a growth chart.

Using and Interpreting Growth Charts for Teens

As teenagers grow and develop, the weight range that is considered “healthy” for them is also shifting. With so many changes occurring, it can be helpful to understand how to interpret growth charts.

Growth charts look at a 18-year old’s weight compared to others of the same height, age, and sex. They can be used to look at trends in a teen’s growth over time.

Listed below are the steps to use and interpret a growth chart for an 18-year old. This will help you better understand how your healthcare provider gets these percentiles and what they mean.

  1. Calculate BMI using height and weight. Although this calculation can be done by hand, the CDC has created an online calculator that makes it easy to figure out BMI. 
  1. Choose the appropriate growth chart. There are two different growth charts, one for girls and one for boys. This is to account for differences in growth patterns between sexes. Both growth charts are shown below.
  1. Look for your age at the bottom of the graph, BMI on the sides of the graph and find the point where those two lines intersect. That will be the point you will evaluate. 
  1. On the right side of the growth chart, you will see the corresponding percentiles. The growth charts below are color-coded to make it easier to read. The red area (>95%) is classified as obese, yellow (85-95%)  is classified as overweight, green (5-85%) is normal weight, and blue (<5%) is underweight.
  1. If you are outside of the “healthy” weight zone, this does not mean you are necessarily unhealthy, but your healthcare provider can do more analysis and keep an eye on the trends to make sure everything is on track!

For Girls. Image Courtesy of Penn State PRO Wellness 

For Boys. Image Courtesy of Penn State PRO Wellness.

What is a Healthy Weight for a 18-Year Old?

Although a “healthy” weight is classified as having a BMI between the 5th and 85th percentiles, there is really not a “perfect” weight that all 18-year old’s should aim for. 

According to the CDC growth charts, an 18-year old female that is 5 foot 4 inches tall is considered at a healthy weight between 102 and 148 pounds (or 46 to 67 kilograms). An 18-year old male that is 5 foot 9 inches tall is considered at a healthy weight between 119-174 pounds (or 54 to 79 kilograms).

What is healthy for one person may not be healthy for another. When looking at eating and exercise habits, even teens that fall in a “healthy” weight range according to BMI and growth charts, might still not be truly healthy when taking other things into account.

Health can be found at any size. Weight is not the main indicator of health. If you find yourself comparing your body shape and weight to those around you, it might be time to take a step back and rethink how you view your health.

What Factors Can Impact an 18-Year Old’s Weight?

Food and exercise habits are the two biggest factors that 18-year olds have control over. However, those are not the only two areas that impact health and weight. There are other things within your control that have a huge impact.

Getting adequate sleep is essential to overall health. The body needs enough time to rest, reset, and repair itself. 8-10 hours of sleep per night is usually adequate for most 18-year olds, but many teenagers do not get that much. Prioritizing sleep is a great way to take care of your overall health.

Mental health also plays a role in weight. High stress levels can impact the balance of hormones in the body which play a role in maintaining weight. Strong emotions can also impact appetite and lead to increased emotional eating.

As 18-year olds dive into adulthood, this is a very important time for them to learn to cope with negative emotions without using food. That might look like seeing a therapist, practicing meditation, finding new hobbies, asking your doctor about medication, or something else!

Should an 18-Year Old go on a Diet?

If you feel pressure to change your body, you are not alone, but dieting for quick results can actually be very harmful to your body.

18-year olds should not participate in any kind of restrictive diet. Eating too few calories and cutting out food groups can lead to missing out on key nutrients essential for this time of development.

Instead of only trying to change your body, focus on healthy eating and exercise habits that are within your control. What really makes your body feel good? When you have good health habits and listen to your body, your weight will get to an appropriate range.

If it feels hard to love your body, practice showing respect to your body. Respect is something you can always focus on. You can’t make positive, lasting health changes if you are coming from a place of self-deprecation or of hating your body. Below are some thoughts that could be helpful in practicing body respect.

  1. My body is strong and resilient.
  1. My body is an amazing machine! Everything in me is working to keep me alive and functioning.
  1. My body helps me do all the things I love.
  1. My body takes care of me even when I don’t always give it what it needs.

When Should an 18-Year Old Lose Weight?

If weight loss is ever recommended by a doctor or dietitian, it should be done under direct supervision of a healthcare professional. However, weight loss is rarely advised for 18-year olds because putting too much emphasis on weight can lead to other negative feelings, behaviors, and habits.

Slowing the rate of weight gain, rather than losing weight should be the main goal. How can you include more healthy habits in your daily routine? Finding small ways of implementing sustainable changes is a much better approach to health than a quick weight loss diet.

Talk openly with your healthcare provider about your concerns with weight. If your healthcare provider makes you feel poorly because of your weight, find someone different to work with! They should be able to help you make positive health changes regardless of the number on the scale!

Healthy Eating Habits for an 18-Year Old for a Healthy Weight

  1. Get a balance of carbohydrates, proteins, and fats every time you eat. You can eat all of your favorite foods, while still being properly nourished, fueled, and satisfied. 
  1. Remove distractions while you eat. Focus on your 5 senses and really connect with the food you are eating. Make sure the food you choose is enjoyable to you!
  1. Try to get a fruit or vegetable every time you eat! The vitamins and minerals in these food groups will help support your body in doing everything you want to do!
  1. Take breaks to evaluate your hunger and fullness levels while you eat. Try to find that point at which you feel satisfied without getting overly full.
  1. Eat regularly throughout the day to properly fuel your body. Do not let yourself get to a point where you are absolutely ravenous. It is much harder to be mindful when you get overly hungry.

Healthy Exercise Habits for an 18-Year Old

  1. Find ways to be active for at least 60 minutes per day. Not only is exercise beneficial for physical health, but it has also been shown to help with stress levels and improve mental health.
  1. Do a wide variety of activities that help strengthen your heart, muscles, and bones. 
  1. If you sit for long periods of time, try to take breaks to get up and move.

Summary

Learning to take care of your physical, mental, and emotional well-being will increase your confidence and prepare you to begin your journey as a more independent adult. You will feel good, and be able to reach an appropriate weight if you respect your body, give it what it needs, and practice healthy eating and exercise habits. 

Resources

Centers for Disease Control and Prevention. About Child and Teen BMI. Cdc.gov. Published March 17, 2021.

Centers for Disease Control and Prevention. Childhood Obesity Causes and Consequences. Published March 19, 2021. 

Centers for Disease Control and Prevention. Sleep in Middle and High School Students. Cdc.gov. Published September 10, 2020. 

Stanford Children’s Health. The Growing Child: Teenager (13 to 18 years). Copyright 2021.  

Katherine Harmer, RDN

I'm a Registered Dietitian Nutritionist with a love for coaching others to success in their health goals, especially teenage athletes. Tennis was my sport of choice in high school. Now I'm a little bit older, a little bit smarter, and a little bit worse at tennis.

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