14 August 2026

What is the difference between overweight and obesity?

The difference between overweight and obesity lies in the degree of fat accumulation and the associated health risks. Being overweight means that someone has more body weight than is healthy for their height, whereas obesity is a more severe stage in which excess body fat actively threatens health. Both are typically determined using the Body Mass Index, but the boundary between the two has concrete medical significance. This article answers the most frequently asked questions about weight categories, risks and treatment options.

At what BMI do you consider someone to be overweight or obese?

Overweight starts at a BMI of 25 or higher, and obesity at a BMI of 30 or higher. A BMI between 25 and 29.9 falls into the overweight category. From 30 onwards, it is referred to as obesity, which is further subdivided into three classes based on severity and health risk.

The BMI, or Body Mass Index, is calculated by dividing body weight in kilograms by the square of height in metres. The classification is as follows:

Healthy weight: BMI 18.5 to 24.9
Overweight BMI 25 to 29.9
Obesity class I: BMI 30 to 34.9
Obesity Class II: BMI 35 to 39.9
Class III obesity (severe obesity): BMI 40 or higher

For people with an Asian background, lower threshold values sometimes apply, because health risks can occur in them at a lower BMI. The BMI is a useful screening tool, but does not give a complete picture of someone's health. Muscle mass, fat distribution and age also play a role.

What health risks are associated with being overweight versus being obese?

Being overweight already increases the risk of conditions such as high blood pressure, type 2 diabetes and cardiovascular disease. In cases of obesity, these risks are significantly greater and additional complications arise, such as sleep apnoea, joint problems, fatty liver disease and an increased risk of certain types of cancer.

The distinction in health risks between overweight and obesity is not only quantitative but also qualitative. In the case of overweight, it is often an increased risk that can be readily influenced by lifestyle changes. In obesity, particularly classes II and III, the strain on the body is so great that medical supervision is almost always necessary.

Specific risks that are more strongly associated with obesity than with overweight include:

Severe insulin resistance and type 2 diabetes
Obstructive sleep apnoea
Non-alcoholic fatty liver disease (NAFLD)
Chronic joint pain, particularly in the knees and hips
Increased risk of stroke and heart failure
Psychological complaints such as depression and reduced self-confidence

The longer someone lives with obesity without treatment, the greater the chance of permanent damage to organs and the musculoskeletal system. Early intervention therefore has a considerably greater impact in the long term.

Is waist circumference a better measure than BMI?

Waist circumference is not a replacement for BMI, but a valuable addition. While BMI measures total body weight in relation to height, waist circumference provides insight into the amount of belly fat, also known as visceral fat. That type of fat is particularly harmful because it surrounds the organs and directly contributes to metabolic risks.

The guidelines for an increased health risk based on waist circumference are:

Men: increased risk with a waist circumference of 94 cm or more, substantially increased at 102 cm or more
Women: increased risk at 80 cm or more, greatly increased at 88 cm or more

Someone with a BMI in the overweight category but a large waist circumference can have a higher health risk than someone with a higher BMI but a smaller waist measurement. Conversely, a muscular person can have a high BMI without an increased risk. Doctors therefore use both measurements together for a more complete picture of someone's weight and health.

When is medical treatment for overweight necessary?

Medical treatment for overweight is indicated when lifestyle changes do not yield sufficient results, when there are weight-related health problems, or when the BMI exceeds 30. With a BMI above 35 in combination with comorbidities, medical supervision is almost always indicated.

In practice, there are several signs indicating that losing weight independently is no longer sufficient:

Repeated unsuccessful weight loss attempts
Presence of diabetes, high blood pressure or other weight-related conditions
Severe fatigue, joint problems or sleep issues due to weight
A BMI of 30 or higher, certainly in combination with a large waist circumference

Medical treatment does not automatically mean medication. A doctor assesses which approach is appropriate for each individual, with lifestyle coaching always remaining a part of it. Not everyone is eligible for medicinal treatment; that depends on the individual situation and medical background.

What are the most effective treatments for obesity?

The most effective treatments for obesity combine lifestyle modification with medical or surgical support. Lifestyle intervention, consisting of dietary adjustment, exercise and behavioural change, forms the foundation. Medical treatment, such as GLP-1 medication, can contribute to weight loss when lifestyle modification alone does not have a sufficient effect.

Lifestyle intervention as a foundation

Every obesity treatment starts with lifestyle change. A structural calorie deficit, more exercise and adaptation of eating behaviour are proven effective in the long term. Guidance by a dietician or lifestyle coach significantly increases the chance of lasting success. Without behavioural change, the chance of relapse after weight loss is high, regardless of the treatment method.

Medical treatment

GLP-1 medication is a class of medicines that suppresses appetite and supports blood sugar regulation. This medication can contribute to weight loss in people with obesity, but is only prescribed after medical assessment. Results vary per person and the medication works best in combination with lifestyle changes. A doctor determines whether someone is eligible based on their health history and current situation.

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Bariatric surgery

In severe obesity, generally from a BMI of 40 or from 35 with severe comorbidities, bariatric surgery can be considered. Procedures such as a gastric sleeve or gastric bypass lead to significant and long-term weight loss. This is a major option that requires extensive medical preparation and aftercare.

How Wellumo helps with overweight and obesity

Wellumo offers medical support for people who want to take steps regarding overweight or obesity, but do not know where to start or experience barriers with their GP. The programme is entirely online, discreet and guided by Dutch-registered (BIG) doctors.

This is how it works at Wellumo:

People are starting with a Medical intake via a questionnaire, so that a doctor can properly assess the situation
A BIG-registered doctor independently assesses the application and determines whether a treatment is appropriate and medically sound.
Upon approval, a prescription will be drawn up and sent to the cooperating pharmacy.
Medication is delivered discreetly to your home, with the option of a subscription for repeat deliveries
Prices are communicated transparently in advance, with no hidden costs

Not everyone is eligible; the doctor decides on a person-by-person basis whether a treatment is appropriate. Would you like to know exactly how the process works? Read more about Wellumo's working method of neem Contact us for more information. Start an intake and let a doctor assess which approach suits your situation.