"Too skinny" is generally defined by a Body Mass Index (BMI) of less than 18.5 kg/m² for most adults. This indicates a potentially unhealthy weight relative to height, but a healthcare provider should make the final determination, as the number alone does not account for all health factors.
under 18.5kg/m2 – you are considered underweight and possibly malnourished. 18.5 to 24.9kg/m2 – you are within a healthy weight range for young and middle-aged adults. 25.0 to 29.9kg/m2– you are considered overweight. over 30kg/m2 – you are considered obese.
If your BMI is under 18.5kg/m2 then you would be considered underweight.
A BMI below 18.5 would be underweight for most adults (over age 15). For children, underweight means having a BMI below the 5th percentile. (That's less than 95% of children their age.) BMI is based on population averages.
Too Skinny: What BMI is Considered Underweight? From a clinical perspective, an individual is considered “too skinny” if they are deemed underweight. According to the Centers for Disease Control, an individual is underweight if their Body Mass Index (BMI) is below 18.5 [1].
A BMI of less than 18.5 suggests underweight. A BMI of between 18.5 and 24.9 suggests a healthy weight range. A BMI of between 25 and 29.9 may indicate overweight. A BMI of 30 or higher may indicate obesity.
Body Shapes with the Highest Risk of Health Problems
Apple and pear body shapes tend to have the highest risk. Apples tend to be at greater risk for heart disease, diabetes, and strokes because they hold a larger amount of tummy fat.
50 kg (about 110 lbs) isn't a "perfect" weight for everyone; it depends heavily on your height, body composition (muscle vs. fat), age, sex, and frame size, with it potentially being healthy for shorter individuals but underweight for taller people, so using a BMI calculator and consulting a doctor is best for a personalized assessment.
The 3-3-3 rule for weight loss is a simple, habit-based method focusing on three key areas: 3 balanced meals a day, 3 bottles (or ~1.5L) of water by 3 PM, and 3 hours of physical activity per week, aiming for consistency over complex diets. It simplifies fat loss by establishing rhythm through consistent eating, adequate hydration to support metabolism, and regular movement, promoting sustainable health without intense calorie counting or restrictive rules, says Five Diamond Fitness and Wellness, Joon Medical Wellness & Aesthetics, and EatingWell.
The Complications of Being Too Thin
Registered dietitian Katherine Basbaum shares, “It's a jumping-off point to determine a healthy weight, but definitely not one-size-fits-all of healthy body factors." To get a rough idea, if your BMI is less than 18.5, you're considered underweight.
According to the American Heart Association and World Health Organization guidelines, underweight is defined as a BMI less than 18.5 kg/m² 1, 2. For context: A 40kg woman who is 5'0" (152.4 cm) tall would have a BMI of 17.3 kg/m² A 40kg woman who is 5'4" (162.6 cm) tall would have a BMI of 15.1 kg/m²
Being Thin Can Come With Health Complications and Body Image Therapy Can Help. Sometimes, being underweight can have more immediate adverse health effects than being overweight. Often, fatness is linked to high blood pressure and cardiac issues.
If you're 165 cm tall, a healthy weight is between 54 kg and 68 kg.
Your most consistent and "true" weight is generally in the morning, after using the bathroom and before eating or drinking anything. This provides the most accurate baseline because your body has processed the previous day's food and fluids overnight, resulting in less fluctuation from digestion, water intake, and daily activities. Weighing at the same time, in the same minimal clothing, and under consistent conditions (like in the morning) helps track trends better than weighing at night or randomly.
Do
A weight of 70kg can fall within the healthy weight range for various individuals. Height plays a significant role. A shorter individual might find a BMI of 70kg within a healthy range, whereas a taller person could potentially fall into the overweight or even the obesity category using the same metric.
Her diet included meals like vegetable poha, fruit, roti, and grilled chicken. Alia trained with Yasmin Karachiwala, blending Pilates, cardio, and strength exercises. Her 7-day routine included running, push-ups, yoga, squats, and crunches to tone and lose weight.
According to fitness coach Raj Ganpath, losing 10 kg in 2-3 months is possible but highly unsustainable. He explains that to achieve this, you need a daily calorie deficit of about 1,300, which is extremely difficult to maintain.
Some of the ways she's lost weight include walking, eating more protein, and medication to help with how her body processes food. Clarkson started some of these changes to her diet and exercise routines when she moved to New York City, where she hosts "The Kelly Clarkson Show."
Sleep deprivation has long been linked to an increased risk of becoming overweight or obese. Researchers found that getting less than seven hours of sleep resulted in weight changes and may lead to weight gain, either by increasing food intake or decreasing energy burned.
A BMI below 18.5 indicates a person is underweight. For example, a 5'5” woman weighing under 50kg may be underweight.
The rarest female body type is generally considered the hourglass, characterized by shoulders and hips of similar width with a significantly narrower, defined waist, with studies suggesting less than 10% of women naturally fit this description, while some data points to the inverted triangle (broad shoulders, narrow hips/waist) also being quite rare, potentially under 1% in some views, though hourglass is more consistently cited as the least common overall.
If you have a BMI of less 18.5, you're technically considered underweight. If your flexed biceps measure less than 13.3″ in circumference, that's a good sign that your muscles are smaller than average, and so you could be considered skinny.
Cardiologists generally advise avoiding processed meats, sugary drinks and sweets, and foods high in trans fats and sodium, like most fried foods and salty snacks, because they raise bad cholesterol, blood pressure, and inflammation, significantly increasing heart disease risk. Focusing on whole foods and limiting these culprits is key for heart health.