Obesity isn’t always visible: The risk of ‘normal weight’ but high fat

We have been taught to read health through appearance. If someone looks slim, fits into standard clothing sizes, and doesn’t visibly carry weight, they’re usually assumed to be healthy.

And if the weighing scale stays within range, that assumption feels even more solid. But that picture is starting to crack.Because not all obesity is visible. And not everyone who looks “fit” actually is.Doctors are increasingly seeing patients who fall into a confusing category, people with a normal body weight but unhealthy levels of body fat. It’s subtle. Easy to miss. And often ignored until it starts affecting health in ways that are harder to reverse.Dr. Aastha Gupta, Senior IVF Consultant and infertility expert, Obstetrics & Gynaecology at Delhi IVF, New Delhi, explains it in a way that sticks: "It's possible for someone who appears thin to actually have a lot of body fat i.e.. a person who suffers from what has come to be termed as normal weight obesity, the presence of excessive fat stored inside the body and near organs, thus posing an increased risk of developing diabetes, cardiovascular disease, and other metabolic diseases.

But because they are within a normal weight range it is difficult for most people to notice. Poor diet, not exercising, and very low muscle mass lead to this condition. The only way to identify and manage this condition is to determine the individual’s body composition, measure their waist size and maintain an active lifestyle."That last line is key. Because what’s happening inside the body often tells a very different story than what we see on the outside.

The body you see vs the body you have

For years, Body Mass Index, or BMI, has been the go-to measure for assessing weight. It’s simple. It’s quick. But it’s also limited.BMI doesn’t tell you how much of your body is muscle and how much is fat. It doesn’t show where that fat is stored. And that’s where the real problem begins.Dr. Manish Kumar Tomar, Senior Consultant - Gastroenterology, Medanta Hospital Noida, puts it plainly: “Normal weight obesity describes people who have a normal BMI yet have a large quantity of body fat, especially visceral, around the organs.

Genetically, they appear to be fit, but by having excess body fat, metabolic risks can exist within the body. Studies show that as many as 25% of the population are affected by normal weight obesity.

This affects a larger number of people than is commonly thought.”So you could be within your “ideal” weight range and still carry fat around your liver, pancreas, and heart. And that kind of fat, visceral fat, isn’t just sitting there.

It’s active. It interferes with hormones, metabolism, and how the body handles sugar and fat.

Why it happens more than you think

It’s easy to assume that hidden obesity is rare. But lifestyle has quietly shifted in ways that make it more common.Long hours of sitting. Meals that are quick but not balanced. Fitness routines that skip strength training. And a general focus on weight rather than body composition.Dr. Tomar explains, “Some examples of how someone looks slim would include someone who has very little muscle mass and a significant amount of fat internally, which are both commonly associated with lean non-alcoholic fatty liver disease.

Sedentary behaviour, poor diets, and lack of strength training also lead to decreased skeletal muscle and increased fat storage in general.”So even if the scale doesn’t move much, the body is changing. Muscle slowly decreases. Fat quietly increases. And because there’s no obvious weight gain, it goes unnoticed.And then there’s diet. High sugar intake, processed foods, and low protein consumption all play a role.

Not dramatically, not overnight—but steadily.

The health risks you don’t see coming

This is where things get serious. Because hidden obesity doesn’t stay hidden forever.It starts affecting the body in ways that aren’t always immediate, but are definitely significant.Dr. Tomar says, “Although those with hidden obesity appear healthy, they are at a higher risk of developing multiple serious health issues. Weight problems may not present an obvious health threat like cardiovascular disease or insulin resistance.

Other life-threatening problems that may arise due to hidden obesity can include liver disease, specifically fibrosis and cirrhosis.”And that’s the unsettling part. Someone may feel fine. Look fine. Function normally. And yet, internally, there could be early signs of insulin resistance, fatty liver, or even cardiovascular strain.

So how do you know?

This is where things need a shift. Because stepping on a weighing scale isn’t enough anymore.Identifying normal weight obesity requires looking deeper, at body composition, not just body weight.Dr. Tomar explains, “While assessing hidden obesity, the method of assessment must go beyond measuring overall body weight. We can identify metabolic and health issues by reviewing routine laboratory tests. The use of imaging technology such as abdominal ultrasound, Fibroscan, or MRI will allow physicians to quantify the amount of fat deposited in the organs e.g.

liver and thus obtain a more accurate assessment of internal health.

”Even something as simple as measuring waist circumference can offer clues. A relatively higher waist size despite normal weight can point towards visceral fat.And then there are blood tests. Blood sugar levels, lipid profiles, liver function tests—they all help piece together the bigger picture.

Rethinking what “healthy” looks like

This condition also forces a rethink of how we define fitness.Because being thin isn’t the same as being healthy. And being heavier doesn’t always mean unhealthy either. It’s more nuanced than that.Dr. Aastha Gupta’s observation brings that nuance into focus again: "The only way to identify and manage this condition is to determine the individual’s body composition, measure their waist size and maintain an active lifestyle."So the focus needs to shift from chasing a number on the scale to understanding what the body is made of.Muscle matters. Fat distribution matters. And how the body functions matters.

What actually helps

The good news is that this isn’t a fixed condition. It can be reversed, or at least improved, with the right changes.But those changes aren’t about crash diets or extreme routines.Dr. Tomar explains it in a grounded way: “Achieving fat loss is more about your body composition than your actual weight, so to lose fat, we should focus on your body composition rather than your weight.

Regular exercise, especially through strength and weight training, builds muscle mass while reducing fat through caloric expenditure. Reducing the amounts of simple sugars and high fat food, along with maintaining a balanced and protein rich diet helps maintain and improve overall metabolic health.

”And that’s where many people go wrong. They focus only on losing weight, often through calorie restriction, without building muscle.

And that can make things worse.Strength training, even a few times a week, can make a real difference. So can increasing protein intake, improving sleep, and just moving more through the day.It doesn’t have to be perfect. But it has to be consistent.

A quiet condition that needs more attention

Normal weight obesity sits in a grey zone. It doesn’t trigger alarm the way visible weight gain does. It doesn’t always come with symptoms that demand attention.And maybe that’s why it’s easy to ignore.But the risks are real. And growing.So the next time someone says, “But you don’t look unhealthy,” it might be worth pausing. Because health isn’t always visible. And sometimes, the body carries more than what meets the eye.Medical experts consulted This article includes expert inputs shared with TOI Health by:Dr. Aastha Gupta, Senior IVF Consultant and infertility expert, Obstetrics & Gynaecology at Delhi IVF, New DelhiDr. Manish Kumar Tomar, Senior Consultant - Gastroenterology, Medanta Hospital NoidaInputs were used to explain how obesity and normal weight is misinterpreted. Doctors have explained what is normal weight obesity, why is it a bigger health risk and how to determine it.