: weighing less than the normal or requisite amount
Examples of underweight in a Sentence
Adjective
the long illness left him frail and underweight
Recent Examples on the Web
Tom Gavin, EverydayHealth.com, 11 Nov. 2025
Strays may appear underweight, often roam alone, and tend to hang around homes.
—Maria Azzurra Volpe, MSNBC Newsweek, 10 Nov. 2025
Normally, that would point to Type 1 diabetes, where individuals are unable to make their own insulin and can become underweight.
—Jonathan Lambert, NPR, 29 Sep. 2025
Obesity can disrupt the body's metabolism, weaken the immune system and lead to diseases like Type 2 diabetes, cardiovascular diseases and up to 15 different cancers, while being underweight is tied to malnutrition, weakened immunity and nutrient deficiencies, Gribsholt warned.
—Deirdre Bardolf, FOXNews.com, 20 Sep. 2025
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Adjective
Consider These Questions Moreau cautions that short-term fasting is not for everyone, and people with medical conditions, or those who are underweight or prone to disordered eating should consult a clinician before making dietary changes.
—Tom Gavin, EverydayHealth.com, 11 Nov. 2025
Strays may appear underweight, often roam alone, and tend to hang around homes.
—Maria Azzurra Volpe, MSNBC Newsweek, 10 Nov. 2025
Normally, that would point to Type 1 diabetes, where individuals are unable to make their own insulin and can become underweight.
—Jonathan Lambert, NPR, 29 Sep. 2025
Obesity can disrupt the body's metabolism, weaken the immune system and lead to diseases like Type 2 diabetes, cardiovascular diseases and up to 15 different cancers, while being underweight is tied to malnutrition, weakened immunity and nutrient deficiencies, Gribsholt warned.
—Deirdre Bardolf, FOXNews.com, 20 Sep. 2025
See All Example Sentences for underweight
Cite this Entry
“Underweight.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/underweight. Accessed 16 Nov. 2025.
Copy CitationMedical Definition
underweight
adjective
un·der·weight
-ˈwāt 
: weighing less than the normal amount for one's age, height, and build
underweight children
underweight adults typically have a body mass index of less than 18.5
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