Whether 55 kg is underweight depends entirely on your height, as BMI (Body Mass Index) uses both weight and height; a lower height with 55 kg could be healthy, but a taller height might place you in the underweight category (BMI under 18.5), increasing risks for nutrient deficiencies and a weakened immune system, so consulting a doctor is best for a personalized assessment.
A BMI of less than 18.5 kg/m² is considered underweight. A BMI between 25 kg/m² and 29.9 kg/m² is considered overweight. A BMI of 30 kg/m² or higher is considered obese. To check your BMI, type your height and weight into the BMI calculator for adults from the National Institute of Health.
Whether a weight of 55 kg is considered skinny or not depends on various factors, including height, body composition, muscle mass, and individual circumstances. Body weight alone does not provide a complete assessment of health, size, or body type.
If you're 165 cm tall, a healthy weight is between 54 kg and 68 kg.
Underweight: BMI is below the 5th percentile age, gender, and height. Healthy weight: BMI is equal to or greater than the 5th percentile and less than the 85th percentile for age, gender, and height. Overweight: BMI is at or above the 85th percentile but less than the 95th percentile for age, gender, and height.
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.
Body mass index (BMI)
BMI is calculated by dividing weight in kilograms by the square of height in metres (kg/m2). BMI in this report is classified into five categories: underweight (BMI less than 18.5kg/m2) normal or healthy weight (BMI 18.5 to 24.9kg/m2)
Why does weight gain happen faster with age? Dr. Mansuri: The metabolism naturally slows down with age, meaning the body burns fewer calories at rest and during physical activity. There is also a gradual loss of muscle mass, known as sarcopenia, which further reduces metabolic rate.
Whether 56 kg (about 123 lbs) is "heavy" for a girl depends entirely on her height, body composition (muscle vs. fat), frame size, and age, as this weight can fall into a healthy range for taller individuals but might be considered heavier for shorter individuals. For example, a 160 cm (5'2") person with a BMI around 22 (normal range) could weigh 56 kg, while a shorter person might be in the overweight category, emphasizing that BMI is just a guide, and factors like muscle mass and how you feel are important too.
Do
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.
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.
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.
That same study shows those who are sleep deprived tend to eat more calories and hormonal changes drive people to pick options that aren't as healthy such as excess carbohydrates. Another common cause of both weight gain and poor sleep is stress. An increase in cortisol levels caused by stress can increase appetite.
If you are underweight (BMI less than 18.5kg/m2), you may be malnourished and develop: compromised immune function. respiratory disease. digestive diseases.
Not eating enough can have several symptoms, such as persistent hunger, low energy, impaired concentration, and frequent sickness. Chronic undereating can have serious health consequences. It's best to consult a healthcare professional or registered dietitian if you suspect you are undereating.
Causes
A well-known 2012 study published in the Journal of Obesity surveyed hundreds of men, showing them images ranging across different body weights and shapes. Most chose women in the healthy BMI range (about 18.5—24.9) as the most attractive—not the super-skinny runway look or an ultra-muscular build.
The answer is yes — but not as drastically as you may think. Metabolism drives the body's basic functions, including converting food into energy to be used immediately or stored for later use. Research shows that metabolism starts to slow down after age 60,2 which may lead to body composition changes or weight gain.