What is the body fat percentage for obesity?

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Learn how body fat percentage relates to obesity, and why it may provide more useful insights than BMI alone.

When we talk about health and weight, the conversation often revolves around a single, familiar concept: BMI.

However, while body mass index is a helpful starting point, it doesn't tell the whole story.

That's where body fat percentage comes in. Looking at actual body composition often gives a much clearer, more accurate picture of your unique health profile.

In one 2025 study, researchers defined 'obesity' as a body fat percentage of:¹

At least 30% for men
At least 42% for women

These numbers are not rigid cut-offs. Factors like age, ethnicity and biological sex can influence what body fat percentage is considered healthy for an individual. However, body fat percentage is seen as a more accurate measure than BMI because it is less affected by differences in muscle mass.

What is body fat percentage?

Body fat percentage refers to the proportion of your total body weight that comes from fat tissue.

Let's say someone weighs 100kg and has a body fat percentage of 30%. That means approximately 30kg of their body weight comes from fat mass.

Having some body fat is essential for normal health. It plays an important role in:

Hormone production
Energy storage
Organ protection
Temperature regulation
Cell function

The goal is not to eliminate body fat completely, but to maintain levels that support long-term health.

Why is body fat percentage useful?

Unlike BMI, body fat percentage helps distinguish between:

Fat mass
Muscle mass
Bone mass
Overall body composition

This is important because two people could have the same BMI but very different health profiles.

For example, someone with high muscle mass may technically fall into the 'overweight' BMI category despite having relatively low body fat levels.

Meanwhile, another person may have a 'healthy' BMI while carrying higher levels of body fat associated with increased health risks.

Body fat percentage can therefore provide a more detailed understanding of metabolic health.

Why is BMI still used more often?

Despite its limitations, BMI remains widely used because it is quick and easy to calculate – all you need is height and weight.

Meanwhile, measuring body fat percentage accurately is more complicated.

Methods include DEXA scans, bioelectrical scales, skinfold measurements, and hydrostatic weighing. Some of these methods can be expensive, while others can be inconsistent depending on hydration, equipment quality and testing conditions.

For this reason, BMI remains the most practical screening tool in many healthcare settings.

Is body fat percentage a better measure than BMI?

In many ways, yes. Body fat percentage often gives a more realistic picture of body composition and health risk than BMI alone.

However, it's important not to focus too much on a single number. Many factors influence our health besides body fat, such as:

Weight loss and body composition

When losing weight, the goal should be to improve body composition over time rather than simply lowering the number on the scales.

This means reducing excess body fat while preserving muscle mass and supporting metabolic health for long-term well-being.

Weight loss medications, such as Wegovy and Mounjaro, can support this process by helping people maintain a calorie deficit more consistently alongside sustainable lifestyle changes.

In clinical trials:

Navigating clinical options and managing your progress requires the right guidance and tools. With SemaPen, professional healthcare support throughout your treatment makes it easier to monitor your overall health profile beyond just a single number on a scale.

Ultimately, sustainable well-being is about considering the bigger picture of your unique body composition.

Semapen is a team of UK weight loss experts. We provide guided support at home through a unique weight loss app. You can find out if you're eligible for treatment today by taking our quick digital consultation.

Sources

1. Potter, A.W. et al. (2025) "Defining Overweight and Obesity by Percent Body Fat Instead of Body Mass Index" The Journal of Clinical Endocrinology and Metabolism,

2. Jastreboff, A.M. et al. (2022) "Tirzepatide Once Weekly for the Treatment of Obesity" The New England Journal of Medicine, 387(3) https://doi.org/10.1056/NEJMoa2206038

3. Wilding, J.P.H. et al. (2021) "Once-Weekly Semaglutide in Adults with Overweight or Obesity" The New England Journal of Medicine, 384(11) https://doi.org/10.1056/NEJMoa2032183

This article was reviewed and approved by Lujain Alhassan, Bariatric Nutritionist, on 1 June 2026.

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