How much should teens weigh to prevent heart disease as adults?

Claire McCarthy, MD
Claire McCarthy, MD, Faculty Editor, Harvard Health Publishing

Follow me at @drClaire

We’ve long known that being overweight can lead to cardiovascular disease and early death. We also know that being overweight as a teen makes it more likely that someone will be overweight as an adult, which is why we pediatricians talk so much to teens and their parents about getting to — and staying at — a healthy weight.

But we may have set the bar too low. A study just published in The New England Journal of Medicine (NEJM) says that if we really want to prevent heart disease in adulthood, our teens should be much thinner than we currently tell them to be.

The number doctors use to figure out if someone’s weight is healthy is the body mass index, or BMI. The BMI is a person’s weight in kilograms divided by the square of their height in meters, and it is a very useful number when it comes to describing how much weight a person is carrying on their body frame. It’s kind of a thinness/fatness index, if you will. For adults, we say that the BMI should be between 18.5 and 24.9 (25 is the cutoff for overweight). For youth 2-20 years old, we use BMI percentiles: we say that a BMI percentile between 5 and 85 is fine, between 85 and 95 is overweight, and 95 or greater is obese.

In Israel, 17-year-olds have a medical exam as a screening for military service. As part of this medical exam, they get a height and weight measurement. For the NEJM study, researchers looked at the height and weight data for 2.3 million Israeli adolescents (mostly boys) taken between 1967 and 2010. They calculated the teens’ BMIs and then followed them out until 2011 to see who died from cardiovascular problems like heart attacks, strokes, or sudden death (which is usually from a cardiovascular cause).

They found that teens whose BMI was in the overweight or obese range, were much more likely to die of cardiovascular causes as adults. Compared with those whose BMI was in the 5th to 24th percentile, teens whose BMI was in the 95th percentile or greater were 4.9 times more likely to die of cardiovascular disease, 2.6 times more likely to die of stroke, and 2.1 times more likely to die of sudden death. Those whose BMI was in the 85th to 94th percentile also had higher risks: 3 times for cardiovascular disease, 1.8 times for stroke, 1.5 times for sudden death. No surprise.

But here’s the surprise: that risk of cardiovascular disease didn’t start at the 85th percentile. The risk started at the 50th percentile. The teens whose BMI was in the 25th to 49th percentile had the lowest risk of cardiovascular disease.

This is a big deal. It goes against what we have been telling people for years.

Let’s use some weights to illustrate. For a 17-year-old boy who is 5 foot 9 inches (average height for 17), the 25th to 49th percentile would be a weight between 132 and 143 pounds. But currently, we tell that boy that it is fine for him to weigh up to 170 lbs. A 17-year-old girl who is an average height of 5 foot 4 inches should weigh between 112 and 122 pounds to prevent heart disease; currently, we tell her that it is fine to weigh up to 148 pounds.

Bottom line: if we want to our children to grow into healthy adults, we need them to be thinner than we currently tell them to be.

Now, there are limitations to this study. The researchers didn’t have a lot of data on the BMIs or lifestyle habits of the teens as they grew, there weren’t as many women as men in the study, and we don’t know if its findings are true for everyone worldwide. But its findings can’t be ignored.

The Centers for Disease Control and Prevention (CDC) has a calculator you can use to find out a child or teen’s BMI percentile. It also has calculators for adults.

If your child or teen’s BMI is in the 50th percentile or higher, don’t panic. Talk to your doctor — and rather than concentrating on a particular weight, concentrate on lifestyle habits. In particular, strive to be sure your child

  • is active for an hour a day
  • eats a diet that includes five servings of fruits and vegetables daily, is low in refined carbohydrates and sugar (including sweetened beverages like soda), low in saturated fat, and high in whole grains
  • gets 8-10 hours of sleep a night
  • spends less than 2 hours a day on entertainment media.

If your child is far off from these, at least set him in the right direction — like by having one extra serving of fruit or vegetables a day, going for a 20-minute walk together, or turning off the TV a half hour earlier at night. Small steps can be the best way to begin — and if we care about the health of our children and our society, we need to begin.

Comments:

  1. Sathya

    I find this article relevant at least in my case. I used to eat a lot lesser than what my teen eats today, and a lot healthier, even though my daughter does not touch diet sodas, there are so many unhealthy diet temptations for all of us today than ever before. She is only 19 years old and already weights what I did when I was 28, despite the fact that she exercises regularly. I am 45 years now and struggling with midlife bulge, and I do wonder and worry what will happen when she reaches my age. BMI, calorie count etc are one thing… I feel we need to lean more towards healthy eating and eating more plant based food, portion control, mindfulness etc. – invariably we have to clean up our act when we get older. Why not start them young? I sometimes feel we need to overhaul our thinking towards food and lifestyle completely.

  2. Janet Newkirk

    Correlation does not equal causality. Basic statistics, being used irresponsibly AGAIN. The last thing we need is more teens skipping meals and drinking more diet sodas. Insofar as this is useful information, it is because it suggests that we look more deeply at teens’ health. Weight itself is a red herring — a symptom, not the problem itself.

  3. Kimberly Yu, S. Bryn Austin, Carly Guss, Allegra R. Gordon, and Erica L. Kenney of the Strategic Training Initiative for the Prevention of Eating Disorders

    While weight is one factor that can affect adult health, pressures on teens to lose weight are already pervasive and can be incredibly damaging to a young person’s mental health and well-being given the ubiquity of weight-related stigma and discrimination in our schools and larger society. Considering the serious health risks associated with eating disorders, statements that pressure teens to be thinner, instead of healthier, especially from healthcare providers and parents, can be more harmful than beneficial even when said with the best of intentions. Additionally, a focus exclusively on weight loss, rather than on overall health, can be counterproductive — extreme efforts to lose weight, instead of focusing on improving health overall, often end up backfiring and resulting in more weight gain and worse relationships with food and physical activity in the long run. We hope that pediatricians and primary care providers will consider the whole person as well as the range of factors that contribute to physical and mental health of youth of all shapes and sizes.

  4. ED HATER

    I found this article, particularly the title, completely upsetting. This type of article will only promote eating disorders, and fuel those struggling with them to stay on a slippery and possibly deadly slope. Every person’s “healthy” weight range is different, and based on their growth since birth! I am so glad the author is not my child’s primary care physician. This is another reason why people, doctors included, NEED to be educated about eating disorders. The number of people who are struggling is staggering, and I realize that the ED field is a specialty, but our kids lives are on the line here.

  5. Taylor Lewis

    Now a days fitness is very important for everyone,so exercise and healthy diet is required.If you are fatty and want to loss weight quickly go to the CalMWM clinic.They will provide you three step weight loss program,during this program you are completely guided by doctors and clinic staff.

  6. Peter Ellis

    I take no issue with the teachings about a health lifestyle. But the CDC’s BMI is grossly misleading. It tells me I’m overweight because a male of my height (6’5″) should weigh between 156 (!) and 210 pounds, while my weight varies between 220 and 227 pounds. But I eat healthily, exercise regularly at moderate to high intensity, get adequate sleep, am in good health and my waist size hasn’t varied in decades. If I set myself a target weight of 156 pounds I’d starve l
    long before I reached that goal. A skeletal appearance is not “normal”!

    • Molly Morrison

      I agree “skeletal” looking I don’t find attractive or beautiful. the women let alone kid should actually eat something. your body will starve your self and your brain will tell your fat cells to stop burning. I am currently on a strict 1200 calorie and less than 50.0g of carbohydrates diet and at least 1-2 hour work out /walk a day. I have lost more that 11 ponuds in a month. Todays diets are outrageous, but I have never felt better. Some diet work for different people. trust me I can understand that but that doesn’t stop me from losing 80 lbs from last month to December. I completely back up some diets work for some people and some don’t it depends on the body type and how much weight you are losing.

  7. RD

    This is an interesting and important discussion, but with the danger of eating disorders among teens due to societal pressures, I question the wisdom of adding medical pressures to the mix. Being thin is better, yes. But “not thin enough”? Where will this end? Sounds like a dangerous message to send teenagers.

  8. Kevin

    Retrospective and observational so don’t look too much into conclusions made here. Also we know, as a population, that we are getting heavier, and so percentiles are deceptive (can’t say I’ve ever been a fan of using them in BMI).

    The real issue here to me is using BMI at all. I’m sure I don’t need to tell you how incorrect BMI can be as a determinant for a healthy weight because it does not factor in body fat %. For example, I am 6’3 235 lbs, which puts me as obese on the BMI scale, but no one would ever call me that since I regularly exercise and am very fit and muscular.

    I agree with the message of the study that people should be more healthy with their weight in general (notice I didn’t say thinner since that isn’t the only way to have a healthy weight, although it is the easiest), but I wouldn’t put too much stock in a study like this since there are so many limitations and confounding factors.

    • Rebecca

      Thank you so much for saying this! The BMI was probably invented by insurance companies so they could avoid paying for the specialized and expensive care of super athletes, most of which would probably come in as obese. Muscle and bone weigh much more than fat and I’ve done the math, there are scenarios where a person could have many more pounds of fat than another but not be considered obese and the person with stronger bones and muscle would be. And this whole argument ‘carrying weight on your frame’. What frame? My father was a mesomorph, and on my lower half I inherited his bones, my knee bone is twice the size of my partner’s and he’s 6’3″. I could never weigh what I’m supposed to without reducing my bone and muscle mass. I’ve had my body fat measured and my lean body mass is greater than what I ‘should’ weigh. This BMI BS needs to stop. Correlations can be very misleading. I won’t stay with a doctor that pushes this concept because they are clearly stupid and gullible.

  9. Hell No

    telling teen girls that they NEED to be a certain weight because of the findings of one study done in a foreign country that didn’t include a lot of women is VERY irresponsible. girls hear this message constantly to begin with and go to extremes more often than not. Find more studies, get more results before publishing an article with this message and click-bait title.

    • Rebecca

      Also amen to this comment – irresponsible to push thinness on any child especially girls. Children need to be taught to eat intuitively. Many studies have proven that when shame is present around food eating disorders follow.