Being Underweight Can Interfere With Stroke Recovery

A phenomenon that medical researchers have dubbed "the obesity paradox" describes the observation that being underweight interferes with recovery after a stroke. While being underweight does not increase the chances of having a stroke, people who are underweight are more likely to have worse outcomes or to die from a stroke than normal weight or overweight counterparts.

Woman using scale to weigh herself

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Defining Underweight

Underweight is defined as having a body mass index (BMI) of less than 18.5. This means that:

  • An adult who is less than 4 feet 8 inches would be considered underweight if they're more than 6 pounds under their ideal weight.
  • An adult who is 5 feet 7 inches would be considered underweight if they're more than 10 to 12 pounds less than ideal body weight.
  • A person who is taller than 5 ft 7 in would have to be more than 12 pounds under ideal body weight to be considered underweight.

If you want to know where you fit in terms of BMI, you can calculate your own by:

  1. Squaring your height in inches.
  2. Dividing your weight in pounds by that number.
  3. Multiplying that result by 703 to determine your BMI.

But, there are faster ways to know your BMI by just entering your height and weight into one of the many BMI calculators available online! 

How Being Underweight Contributes to Stroke Outcome

A stroke is one of the most stressful battles that your body may ever have to face. There are several reasons that being underweight can contribute to a worse outcome and an increased risk of death after a stroke.

  • Nutritional status: After a stroke, the body has to put up an intense fight to heal. The human body consumes a substantial supply of nutritional resources to mount the uphill repair process, including vitamins, minerals, carbohydrates, proteins, and stored fats. Those reserves don't come out of nowhere—some come from diet, medications, and supplements, but most come from the body itself. And that is one of the reasons that being underweight is a problem. Underweight people do not have enough nutrients to overcome the physical challenges of a stroke.
  • Anemia (low red blood cell count or function): Anemia has also been associated with worse stroke outcomes. Normal red blood cell (RBC) function relies on nutrients such as vitamin B12 and iron. Anemia is common among people who have worse nutritional status. And, it turns out that anemia may be associated with worse stroke outcomes even among people who have normal or above normal weight.

Maintaining Normal Weight

Most people battling excess weight would consider this an odd concern. But, over the years, your eating habits and activity levels, not to mention your hormones, can change and may cause weight loss. Depression often interferes with appetite, making matters worse.

It is important to make sure that you get enough calories and that you also have a well-rounded diet that includes a variety of vitamins, minerals, carbohydrates, proteins, and fats.

If you are having a hard time keeping yourself from being underweight, you should begin by trying to figure out if you are eating enough. If you are eating a reasonable amount of calories and you're still underweight, you should check with your healthcare provider to see if you have a hormonal problem such as a thyroid problem, or a malabsorption problem that could be interfering with your body absorbing the calories from the food you eat.

You may need to consult with a nutritionist to improve your diet so you can keep the needed pounds on.

A Word From Verywell

Overall, being overweight is not healthy. But turns out that while obesity increases the chances of having a stroke, obesity surprisingly decreases the chances of stroke death and recurrent strokes.

But few people know that being underweight is damaging to the body, too. In addition to impaired stroke recovery, being underweight increases the risk of heart attacks, as well.

Maintaining a normal weight is among the important steps to staying healthy for the long term.

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3 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Huang K, Liu F, Han X, et al. Association of BMI with total mortality and recurrent stroke among stroke patients: A meta-analysis of cohort studiesAtherosclerosis. 2016;253:94-101. doi:10.1016/j.atherosclerosis.2016.08.042

  2. Kubo S, Hosomi N, Hara N, et al. Ischemic stroke mortality Is more strongly associated with anemia on admission than with underweight statusJ Stroke Cerebrovasc Dis. 2017;26(6):1369-1374. doi:10.1016/j.jstrokecerebrovasdis.2017.02.016

  3. Park D, Lee JH, Han S. Underweight: Another risk factor for cardiovascular disease?: A cross-sectional 2013 Behavioral Risk Factor Surveillance System (BRFSS) study of 491,773 individuals in the USAMedicine (Baltimore). 2017;96(48):e8769. doi:10.1097/MD.0000000000008769

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