Written by Dr. Simon Khela MBChB MRCGP, GMC Registered Doctor
Last reviewed: 28-07-2026
_________________________________________________________________________
One of the most common questions I hear in clinic is:
"Doctor, how much should I actually weigh?"
It sounds like a simple question, but the answer is rarely straightforward.
Many people search online for an "ideal weight" based on their height or age, hoping to find a single number that tells them whether they're healthy. In reality, your healthy weight depends on several factors, including your body composition, muscle mass, ethnicity, age, sex and overall health—not just the number on the scales.
I've looked after patients who were worried about being "overweight" despite having excellent cardiovascular health, and others whose weight appeared normal but who had underlying health risks that required medical attention. This is why weight should always be considered as part of the bigger picture rather than in isolation.
In this guide, I'll explain how doctors assess healthy weight, what Body Mass Index (BMI) can and cannot tell us, how age influences body weight, and why focusing on long-term health is far more important than chasing a specific number.
There is no single ideal weight for everyone. Healthcare professionals use several measures—including Body Mass Index (BMI), waist circumference, body composition and your overall health—to determine whether your weight is within a healthy range. While BMI provides a useful starting point for most adults, age, muscle mass, ethnicity and existing medical conditions should also be taken into account.
As a general guide:
Maintaining a healthy weight isn't about achieving a certain appearance—it's about reducing your risk of developing preventable health conditions and improving your quality of life.
Research consistently shows that carrying excess body fat can increase the risk of several long-term conditions, including:
At the same time, being significantly underweight can also affect your health by increasing the risk of:
One of the biggest misconceptions I encounter is that weight alone determines health. In reality, two people with exactly the same weight can have very different levels of fitness, muscle mass and overall health.
Body Mass Index, more commonly known as BMI, is one of the simplest tools doctors use to estimate whether someone's weight is appropriate for their height.
BMI is calculated using a person's:
The formula is:
BMI = Weight (kg) ÷ Height (m²)
Although the calculation is straightforward, its interpretation requires context.
BMI does not directly measure:
Instead, it acts as a screening tool that helps identify people who may benefit from further assessment.
Many patients are surprised to learn that BMI was never intended to be a perfect measure of health. Rather, it provides a useful starting point for identifying whether someone may be at increased risk of weight-related conditions.
These categories are widely used by the NHS and NICE to guide clinical decision-making, although they should always be interpreted alongside other health factors.
Many people prefer to know their recommended weight rather than their BMI.
The table below provides approximate healthy weight ranges for adults based on a BMI between 18.5 and 24.9.
These figures are estimates rather than targets.
For example, a muscular athlete may weigh more than the healthy range because muscle is denser than fat, while an older adult may fall within the healthy range despite having reduced muscle mass.
This is another question I hear frequently in practice.
The simple answer is:
Not directly.
Unlike children, whose healthy weight changes continuously as they grow, adult BMI categories remain the same throughout adulthood.
However, age does influence how weight affects your health.
Younger adults generally have:
This means BMI may slightly overestimate body fat in physically active individuals.
Between the ages of approximately 40 and 60, many people naturally experience:
This often explains why maintaining a healthy weight becomes more challenging despite similar eating habits.
One of the most common concerns I see in practice is patients telling me:
"I haven't changed my diet, but I've gained weight."
Often, age-related changes in metabolism and muscle mass contribute to this gradual increase.
For older adults, maintaining muscle strength may become just as important as maintaining a particular weight.
Losing too much weight later in life can increase the risk of:
This is why healthcare professionals often focus on preserving muscle mass rather than encouraging aggressive weight loss in older patients.
BMI is an excellent population screening tool, but it has limitations.
It may not accurately reflect health in:
For example, a professional rugby player may technically have a BMI within the obesity range despite having very little body fat.
Similarly, an older person with a "healthy" BMI may have lost significant muscle mass, which BMI alone cannot detect.
This is why doctors never rely on BMI in isolation when making clinical decisions.
A question I am frequently asked is whether someone should aim for the exact weight shown on an online BMI calculator.
My answer is usually no.
The healthiest weight for you is one that supports good physical health, allows you to stay active, reduces your risk of disease and is realistic to maintain over the long term.
Numbers can be helpful, but they should never become the sole measure of your health or wellbeing.
Although BMI is a useful starting point, it doesn't tell us where fat is stored or how much of your weight comes from muscle rather than body fat.
In general practice, I rarely make recommendations based on BMI alone. Instead, I consider your overall health, medical history, lifestyle and other measurements that provide a more complete picture.
For example, two people may both have a BMI of 28, but their health risks could be very different depending on:
This is why a personalised assessment is often far more valuable than relying on a single number.
One of the most useful measurements alongside BMI is waist circumference.
Carrying excess fat around the abdomen—sometimes called central obesity—is more strongly associated with conditions such as:
Even people whose BMI falls within the healthy range may have an increased health risk if they carry excess abdominal fat.
Men
Women
Your healthcare professional may measure both your BMI and waist circumference when assessing your overall health risk.
Many patients expect a GP consultation about weight to focus solely on the scales.
In reality, we consider a much wider range of factors.
This may include:
Depending on your symptoms and risk factors, your doctor may also recommend blood tests to check for conditions that can affect weight, including thyroid disorders, diabetes or nutritional deficiencies.
For people with several risk factors, a comprehensive health check can provide a broader assessment of cardiovascular and metabolic health rather than focusing on weight alone.
Seeing a BMI in the overweight or obesity range can feel worrying, but it's important not to panic.
BMI is designed to identify people who may be at increased risk—not to diagnose illness.
The next steps usually involve looking at your overall health rather than immediately trying to achieve an "ideal" weight.
A gradual reduction in weight of just 5–10% of your starting body weight can lead to meaningful improvements in:
One of the most encouraging conversations I have with patients is explaining that they don't necessarily need to reach a "perfect" BMI to experience significant health benefits.
Being underweight receives far less attention than obesity, but it can also affect your health.
Possible causes include:
Symptoms may include:
If you've unintentionally lost weight or remain underweight without a clear explanation, it's important to seek medical advice.
Absolutely.
Muscle is denser than fat.
As a result, physically active people often weigh more without carrying excess body fat.
Examples include:
This is why BMI sometimes classifies muscular individuals as overweight or obese despite excellent overall health.
Many patients become discouraged because the scales don't move as quickly as they hoped.
However, there are many signs that your health is improving even if your weight changes slowly.
These include:
Focusing on these improvements often leads to better long-term motivation than concentrating solely on body weight.
There is no single diet or exercise programme that works for everyone.
The most successful approaches are usually those that people can maintain over the long term.
Healthy habits include:
Some people with obesity or weight-related health conditions may also be suitable for weight loss injections alongside lifestyle changes. These medications are not a quick fix and should only be used following an appropriate clinical assessment.
Fact: Healthy weight varies depending on age, sex, body composition, muscle mass and overall health.
Fact: BMI is only one screening tool. Doctors also consider waist circumference, medical history, lifestyle and metabolic health.
Fact: Being underweight can also increase health risks. The aim is a healthy, sustainable weight rather than the lowest possible number.
Fact: Gradual, sustainable weight loss is more likely to be maintained and may reduce the risk of regaining weight.
Fact: People with a healthy BMI can still have high blood pressure, raised cholesterol or other medical conditions that require attention.
There is no single ideal weight. Your healthy weight depends on factors such as your height, body composition, age, sex and overall health. BMI provides a useful starting point for most adults.
For most adults, a healthy BMI is between 18.5 and 24.9. However, BMI should be interpreted alongside other health measures.
Not directly. While the healthy BMI range remains the same throughout adulthood, ageing can change muscle mass, body fat and metabolism.
No. BMI doesn't distinguish between muscle and fat, so it may be less accurate for athletes, older adults, pregnant women and some ethnic groups.
Yes, in some cases. Overall health depends on many factors, including waist circumference, fitness level, blood pressure and metabolic health—not BMI alone.
For most adults, losing 5–10% of your body weight can provide significant health benefits, even if you don't reach your ideal BMI.
Being underweight can also affect your health. If you've lost weight unexpectedly or have a BMI below 18.5, it's worth seeking medical advice.
You should seek medical advice if you're concerned about your weight, have unexplained weight changes or have weight-related health conditions such as diabetes or high blood pressure.
Yes. Excess fat around the waist is associated with a higher risk of conditions such as heart disease and type 2 diabetes, even if your BMI is within the healthy range.
Long-term healthy habits—including a balanced diet, regular exercise, good sleep and not smoking—are generally more important than achieving a specific weight.
Same Day Online Booking
No Time Limits Appointments
Online Consultations Available
Latest Blog Posts
What Teas Can Help Relieve Migraines?
What to Know About "Ozempic Face"
Why Is Moringa Good for You? Benefits, Nutrients and Safety
Apple Cider Vinegar- Unravelling the Health Benefits, Are the Rumours True?
Scabies: Causes, Symptoms, Treatment & How to Prevent the Spread
How to Inject Mounjaro — A Complete Guide
Ready to take the next step?
Before you go
STRUGGLING WITH HAYFEVER THIS SEASON?
Our hayfever treatment is fast, effective often providing relief within 24 hours.
Book Hayfever Treatment →Book a Hayfever Appointment