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Underweight vs. Overweight: What's the Difference?

Edited by Aimie Carlson || By Harlon Moss || Updated on November 18, 2023
Underweight refers to weighing less than what is considered healthy for a given height, while overweight is weighing more than what is healthy.

Key Differences

Being underweight means having a body weight lower than what is deemed healthy for a person's height, often indicating inadequate nutrition or underlying health issues. Overweight, conversely, refers to excess body weight compared to standard height-weight charts, often due to excess body fat.
Underweight individuals may face health risks like weakened immunity, osteoporosis, or fertility issues. Overweight individuals are at a higher risk for health issues such as heart disease, diabetes, and joint problems.
Underweight can result from various factors, including genetics, medical conditions, or insufficient calorie intake. Overweight typically results from overeating, lack of physical activity, genetics, or metabolic factors.
In terms of management, gaining weight healthily for underweight individuals involves a balanced diet and sometimes medical intervention. For overweight individuals, weight loss strategies include diet modifications, increased physical activity, and sometimes medical treatment.
Both underweight and overweight conditions require a holistic approach to health, focusing on nutrition, lifestyle, and mental well-being, under medical supervision when necessary.

Comparison Chart


Weighing less than what is healthy
Weighing more than what is healthy

Health Risks

Weakened immunity, osteoporosis
Heart disease, diabetes

Common Causes

Poor nutrition, genetics, illness
Overeating, inactivity, genetics


Balanced diet, medical intervention
Diet, exercise, sometimes medication

Focus in Treatment

Gaining weight healthily
Losing excess weight

Underweight and Overweight Definitions


A BMI below the healthy range.
His BMI classified him as underweight.


A BMI above the healthy range but below obesity.
His BMI indicated he was overweight.


Weighing less than the standard for one's height.
The doctor was concerned she was underweight for her age.


A risk factor for various health issues.
Being overweight can increase the risk of heart disease.


Sometimes a result of high metabolism or genetics.
Despite eating well, he remained underweight due to his high metabolism.


Often linked to excessive fat accumulation.
Overweight conditions are frequently associated with excess body fat.


Indicative of inadequate nutrition or health issues.
Being persistently underweight can signal health problems.


Exceeding the standard body weight for one's height.
The health campaign focuses on the risks of being overweight.


A condition needing medical attention and dietary adjustments.
She received a diet plan to address her underweight status.


Managed through diet, exercise, and lifestyle changes.
She successfully managed her overweight condition with lifestyle changes.


Weighing less than is normal, healthy, or required.


Weighing more than is normal, necessary, or allowed, especially having more body weight than is considered normal or healthy for one's age or build.


Insufficiency of weight.


Are underweight individuals always malnourished?

Not necessarily, but underweight can often indicate nutritional deficiencies.

What is the BMI range for being underweight?

A BMI under 18.5 is typically considered underweight.

What BMI range indicates being overweight?

A BMI between 25 and 29.9 is classified as overweight.

Can stress cause underweight?

Yes, stress can lead to weight loss and underweight conditions.

How does being overweight affect mental health?

It can lead to issues like low self-esteem, depression, and anxiety.

Can children be underweight or overweight?

Yes, children can be either, and it's important to manage it for their health.

Can being underweight affect fertility?

Yes, being underweight can affect both male and female fertility.

How can underweight individuals gain weight healthily?

By eating nutrient-rich foods and possibly under medical guidance.

Is being overweight always due to overeating?

Not always; factors like genetics and metabolism also play a role.

What lifestyle changes help manage overweight?

Regular exercise and a balanced diet are key to managing weight.

Are there specific medical conditions associated with being underweight?

Conditions like hyperthyroidism and eating disorders can cause underweight.

Is it easier to treat underweight or overweight conditions?

It varies individually and depends on underlying causes and health factors.

What are the health risks of rapid weight loss in overweight individuals?

Rapid weight loss can lead to nutritional deficiencies, gallstones, and other health issues.

Is medication necessary for managing overweight?

In some cases, medication may be prescribed, but lifestyle changes are fundamental.

Can overweight lead to diabetes?

Yes, being overweight is a risk factor for type 2 diabetes.

What are some psychological factors leading to underweight?

Stress, anxiety, and body image issues can contribute to underweight.

Does genetics play a role in being overweight?

Yes, genetics can influence body weight and the risk of being overweight.

What role does diet play in being underweight?

Diet plays a crucial role, as poor or inadequate diet can lead to underweight.

Can overweight be cured permanently?

It can be managed effectively with lifestyle changes, but ongoing effort is often needed.

Does being underweight always indicate an eating disorder?

Not always, but eating disorders are a common cause of underweight.
About Author
Written by
Harlon Moss
Harlon is a seasoned quality moderator and accomplished content writer for Difference Wiki. An alumnus of the prestigious University of California, he earned his degree in Computer Science. Leveraging his academic background, Harlon brings a meticulous and informed perspective to his work, ensuring content accuracy and excellence.
Edited by
Aimie Carlson
Aimie Carlson, holding a master's degree in English literature, is a fervent English language enthusiast. She lends her writing talents to Difference Wiki, a prominent website that specializes in comparisons, offering readers insightful analyses that both captivate and inform.

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