Many people use the terms overweight and obesity as though they were synonymous, but there is an important clinical distinction between the two. Understanding at what point excess weight ceases to be an aesthetic concern and becomes a genuine health problem is essential for making informed decisions and seeking the right professional help.

What is overweight and what is obesity?

Both overweight and obesity are defined as an excessive accumulation of body fat that can be harmful to health. The difference between the two lies in the degree of that excess.

The most widely used measurement tool in clinical practice is the Body Mass Index (BMI), which is calculated by dividing weight in kilograms by height in metres squared. According to the criteria of the World Health Organisation (WHO):

• Normal weight: BMI between 18.5 and 24.9 kg/m²
• Overweight: BMI between 25 and 29.9 kg/m²
• Grade I obesity: BMI between 30 and 34.9 kg/m²
• Grade II obesity: BMI between 35 and 39.9 kg/m²
• Grade III or morbid obesity: BMI of 40 kg/m² or above

A person who is overweight has excess body weight but has not yet reached the threshold for obesity. Obesity, by contrast, implies a level of fat accumulation high enough to significantly increase the risk of chronic disease.

The limitations of BMI: is it sufficient for diagnosis?

BMI is a useful tool owing to its simplicity, but it has significant limitations. It does not distinguish between muscle mass and fat mass, nor does it take into account the distribution of body fat, which is one of the most relevant risk factors.

For example, a person with a high muscle mass may have an elevated BMI without having true obesity. Conversely, someone with a BMI within the normal range but with high accumulation of abdominal fat — known as normal weight obesity — may have a considerable cardiovascular risk.

For this reason, specialist professionals supplement BMI with other measurements, such as:

• Waist circumference: values above 88 cm in women and 102 cm in men indicate elevated cardiovascular risk.
• Waist-to-hip ratio: assesses the distribution of body fat.
• Body fat percentage: obtained through bioimpedance analysis or DEXA scanning.
• Blood tests: to detect associated metabolic abnormalities.

An accurate diagnosis requires a comprehensive assessment, not merely a figure on the scales.

When does excess weight become a health problem?

Overweight does not always have immediate medical consequences, but it does serve as a warning sign. Many people live for years with a few extra kilograms without noticing any symptoms, whilst others develop metabolic complications even with a moderately elevated BMI.

Obesity, particularly from Grade II onwards, is consistently associated with a wide range of conditions:

• Cardiovascular diseases: arterial hypertension, myocardial infarction, stroke.
• Type 2 diabetes: insulin resistance is one of the most common metabolic consequences.
• Sleep apnoea: excess fatty tissue in the neck area impairs breathing during sleep.
• Joint problems: excess weight increases the load on the joints, accelerating osteoarthritis of the knee and hip.
• Non-alcoholic fatty liver disease (NASH): this can progress to cirrhosis if left untreated.
• Certain types of cancer: including colorectal, post-menopausal breast and endometrial cancer.
• Psychological disorders: anxiety, depression and low self-esteem are common in people with obesity, partly due to associated social stigma.

The point at which excess weight becomes a health problem is not always marked by a precise number on the scales. It also depends on factors such as genetics, age, lifestyle habits and the presence of other conditions. This is why individualised assessment is so important.

The role of the Obesity Unit in Huelva

When overweight or obesity is already affecting quality of life or is associated with chronic conditions, a multidisciplinary approach is required. The Obesity Unit in Huelva, led by Dr Christian Leyva, offers comprehensive care that combines accurate diagnosis, medical treatment and, where indicated, the most advanced surgical options.

The Obesity Unit in Huelva works with a specialist team that assesses each case individually, designing a therapeutic plan tailored to each patient’s real needs — from lifestyle changes and pharmacological treatment to endoscopic techniques or bariatric surgery when conservative measures prove insufficient.

The aim is not simply to reduce the number on the scales, but to improve metabolic health, reduce cardiovascular risk and enhance quality of life on a sustained basis.

When should you consult an obesity specialist?

We recommend seeking a specialist consultation if:

• Your BMI exceeds 30 kg/m².
• You are overweight (BMI between 25 and 29.9) and already have associated conditions such as hypertension, diabetes or sleep apnoea.
• You have tried to lose weight through diet and exercise without achieving lasting results.
• Your waist circumference exceeds the reference values.
• Excess weight is affecting your mobility, sleep or emotional wellbeing.

There is no need to wait until health problems worsen before asking for help. Early intervention always yields better outcomes.

If you are concerned about your weight or are already noticing that it is affecting your health, do not put it off. At the Obesity Unit in Huelva, Dr Christian Leyva specialises in supporting you with a rigorous, personalised treatment focused on long-term results.

Book your consultation today and take the first step towards better health.