Overweight and obesity are increasingly common conditions that can have a significant impact on our health and wellbeing. Although the terms are often used interchangeably, they refer to different levels of excess body weight and may carry different health risks.
Understanding the distinction is essential for identifying potential complications and choosing the most appropriate treatment.
In this article, we explain the difference between overweight and obesity, their main causes, associated health risks and the treatments available to support healthy, sustainable weight loss.
What is overweight?
Being overweight means having excess body weight, often associated with an accumulation of body fat. This fat may be stored beneath the skin or around internal organs, where it is known as visceral fat.
One of the most widely used tools for assessing weight in relation to height is the Body Mass Index (BMI).
BMI is calculated by dividing a person’s weight in kilograms by the square of their height in metres.
For most adults, the standard BMI categories are:
- Healthy weight: BMI between 18.5 and 24.9.
- Overweight: BMI between 25 and 29.9.
- Obesity: BMI of 30 or above.
However, BMI is a screening tool rather than a complete measure of health. It does not distinguish between muscle and fat or show where body fat is distributed.
For this reason, a personalised assessment may also consider waist circumference, body composition, metabolic health and other clinical factors.
What is obesity?
Obesity is a chronic, complex condition characterised by excess body fat that can adversely affect health.
It develops through the interaction of multiple factors, including genetics, hormones, metabolism, lifestyle and environmental influences.
In adults, obesity is commonly classified using BMI:
- Class 1 obesity: BMI between 30 and 34.9.
- Class 2 obesity: BMI between 35 and 39.9.
- Class 3 obesity: BMI of 40 or above.
Although higher BMI categories are generally associated with greater health risks, the impact of obesity varies between individuals.
Some people may develop metabolic complications at a lower BMI, while others may not experience the same health problems despite having a higher BMI.
This is why obesity should be assessed in the context of a person’s overall health, rather than BMI alone.
What is the difference between overweight and obesity?
The main difference between overweight and obesity lies in the degree of excess body fat and its potential impact on health.
Although BMI provides a useful starting point, several factors help distinguish the two conditions.
Body Mass Index (BMI)
BMI is one of the most commonly used methods for classifying overweight and obesity in adults.
- BMI 25–29.9: Overweight.
- BMI 30–34.9: Class 1 obesity.
- BMI 35–39.9: Class 2 obesity.
- BMI 40 or above: Class 3 obesity.
These categories help healthcare professionals identify potential health risks and determine whether further assessment is needed.
However, two people with the same BMI may have very different body compositions and metabolic profiles.
Associated health problems
Beyond BMI, one of the most important considerations is the effect that excess body fat may have on the body.
Both overweight and obesity can increase the likelihood of developing certain health conditions, although risks generally rise as excess adiposity increases.
These conditions may include:
- Type 2 diabetes and insulin resistance.
- High blood pressure.
- Cardiovascular disease.
- Obstructive sleep apnoea.
- Fatty liver disease associated with metabolic dysfunction.
- Joint problems and reduced mobility.
Being overweight does not necessarily mean that someone has an established metabolic disease, but it can be an opportunity to assess risk factors and introduce preventive measures.
Body fat distribution
Another important difference is where excess fat accumulates.
Visceral fat, which surrounds internal organs in the abdominal cavity, is particularly associated with metabolic and cardiovascular risks.
For this reason, measuring waist circumference and assessing body composition may provide valuable information beyond BMI.
What causes overweight and obesity?
Overweight and obesity are influenced by a combination of biological, behavioural and environmental factors.
These can be broadly divided into factors that are more difficult to modify and those that may be addressed through personalised treatment and lifestyle changes.
Biological and genetic factors
Some factors influence a person’s predisposition to gaining weight and may be difficult to change directly.
These include:
- Genetic predisposition: Inherited characteristics can influence appetite, metabolism and fat storage.
- Hormonal and endocrine conditions: Certain medical conditions may contribute to weight gain.
- Physiological changes: Ageing, menopause and changes in body composition can affect energy requirements.
- Family history: Both genetic and shared environmental factors can influence weight.
Understanding these factors can help healthcare professionals develop more realistic and effective treatment strategies.
Lifestyle and environmental factors
Other influences relate to daily routines, living conditions and behaviours.
These may include:
- Low levels of physical activity.
- Dietary patterns that contribute to excess energy intake.
- Prolonged sedentary behaviour.
- Chronic stress.
- Emotional factors that influence eating habits.
- Poor sleep quality or insufficient sleep.
Weight management is not simply a question of willpower. Appetite regulation, biological responses to weight loss and environmental factors all influence long-term outcomes.
For this reason, effective treatment should take the individual’s circumstances into account.
What treatments are available for overweight and obesity?
There are several approaches to managing overweight and obesity, ranging from nutritional and lifestyle interventions to medication, endoscopic procedures and bariatric surgery.
The most appropriate treatment depends on the patient’s BMI, overall health, medical history and individual goals.
Nutrition and physical activity
A personalised nutritional plan combined with regular physical activity is an important foundation of weight management.
Rather than focusing exclusively on rapid weight loss, the aim is to establish sustainable habits that support long-term health.
A treatment plan may include:
- A balanced nutritional approach adapted to individual needs.
- Strength training to help preserve muscle mass.
- Regular cardiovascular activity.
- Strategies to improve sleep and manage stress.
- Ongoing professional monitoring and support.
Preserving muscle mass during weight loss is particularly important for maintaining physical function and supporting long-term weight management.
Endoscopic weight-loss treatments
Endoscopic procedures offer minimally invasive options for selected patients who may benefit from additional support with weight loss.
These procedures are performed using specialised instruments introduced through the mouth, without the need for traditional abdominal incisions.
Depending on the patient’s circumstances, available options may include:
These treatments aim to support weight reduction by influencing stomach capacity, food intake or feelings of fullness, depending on the technique.
However, not every endoscopic procedure is suitable for every patient, and long-term nutritional and medical follow-up remains essential.
Bariatric surgery
For patients with obesity who meet the appropriate clinical criteria, bariatric surgery may be considered.
These procedures can support substantial weight loss and may improve certain obesity-related health conditions.
Surgical options include:
- Gastric sleeve surgery (sleeve gastrectomy)
- Gastric bypass surgery.
The decision to undergo surgery requires a comprehensive medical assessment, including an evaluation of potential benefits, risks and the need for long-term follow-up.
Weight-loss medication
Prescription medication may also form part of a comprehensive obesity treatment plan.
These treatments are generally considered when lifestyle interventions alone have not achieved sufficient results or when additional medical support is appropriate.
Some medicines work by influencing appetite regulation and feelings of fullness, helping patients manage food intake.
Medication should always be prescribed and monitored by a qualified healthcare professional, taking into account the patient’s medical history, treatment goals and potential side effects.
GLP-1 medications for weight loss: how do they work?
GLP-1 receptor agonists are a group of medicines used in the management of type 2 diabetes and, in certain formulations, obesity.
They act on pathways involved in appetite regulation and blood glucose control.
These medicines can help reduce hunger, increase feelings of fullness and support weight loss when combined with appropriate nutritional and lifestyle measures.
Some newer treatments also act on additional hormonal pathways involved in metabolic regulation.
Who may be eligible for weight-loss medication?
Depending on the specific medicine and its approved indications, pharmacological treatment for weight management may be considered for adults with:
- A BMI of 30 or above, indicating obesity.
- A BMI of 27 or above with at least one weight-related health condition, such as hypertension, dyslipidaemia or obstructive sleep apnoea.
These thresholds are commonly used for certain prescription weight-management medicines, but eligibility depends on the product, local authorisation and individual clinical circumstances.
Patients may also present with metabolic conditions such as:
- Elevated blood glucose.
- Insulin resistance.
- Prediabetes.
- Sleep apnoea.
Not everyone with overweight or obesity requires medication. A specialist assessment is necessary to determine whether pharmacological treatment is appropriate.
Can GLP-1 medication help control food cravings?
Some patients taking GLP-1-based treatments report experiencing less hunger, fewer food cravings and a reduction in persistent thoughts about eating.
These effects are linked to the medicines’ influence on appetite and satiety pathways.
However, responses vary between individuals, and these medications should not be presented as treatments for anxiety disorders.
Potential side effects, including gastrointestinal symptoms, should also be discussed before starting treatment.
Personalised weight management at Clínica Planas
Although BMI is a useful starting point, successful weight management requires a broader understanding of each patient’s health.
At Clínica Planas, we believe in a personalised approach that considers body composition, metabolic health, lifestyle, medical history and individual objectives.
Depending on the patient’s needs, treatment may involve nutritional guidance, physical activity, medical management or specialised procedures.
Understanding the difference between overweight and obesity is the first step towards choosing the right treatment and improving long-term health and wellbeing.
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