Difference Between Obesity and Fat

Obesity and fat are two terms that are often used interchangeably to describe a person who is overweight. However, there is a significant difference between the two, and understanding this difference is essential for managing one's weight and overall health.

What is Obesity?

Obesity came from the Latin word, "obesus" which literally means "having eaten until fat". As a medical term, it refers to having a high Body Mass Index (BMI); specifically having a BMI score of at least 30. This condition is often attributed to consuming too many calories, poor metabolism, endocrine issues, and sedentary lifestyle.

Obesity has been specified as an epidemic since a recent survey shows that as many as 70-80% American adults are actually obese. Surprisingly, around 21% of American children, aged 12 to 19 years old, are also obese. Aside from being a precursor of type 2 diabetes, this disease increases inflammation which is hypothesized to be one cause of cancer. The other health complications linked to obesity are hypertension, sleep apnea, infertility, and gallbladder disease.

What is Fat?

This colloquialism originated from the Old English word "fǣtt", which means "well fed" or "plump". Indeed, somebody is described as such when he exhibits a flabby and heavy physique. Fat may also refer to the white or yellowish substances found in the adipose tissue of humans, animals, and plants.

Moreover, fat is a food nutrient such as omega-3 fatty acid which is a good source of energy and helpful in maintaining cells’ health. It may also pertain to being productive or fertile as in the idioms, "the fat of the land" and "a fat contract".

Differences: Obesity and Fat

One of the most significant differences between fat and obesity is that obesity is associated with numerous health problems. These health problems include an increased risk of heart disease, stroke, diabetes, high blood pressure, and certain types of cancer. Obesity can also cause joint problems, sleep apnea, and mental health issues such as depression.

Fat, on the other hand, is not necessarily harmful to health. While excessive fat can lead to obesity, having a moderate amount of body fat can be healthy. Women, in particular, require a higher percentage of body fat than men to maintain optimal health.

The location of body fat also plays a significant role in health. Fat stored around the abdomen is more dangerous than fat stored in other areas of the body. This type of fat, known as visceral fat, can increase the risk of heart disease, stroke, and diabetes.

Another important difference between fat and obesity is the way they are treated. To reduce obesity, a person needs to reduce their overall body fat. This can be achieved through a combination of diet, exercise, and lifestyle changes. It is essential to maintain a calorie deficit by consuming fewer calories than the body burns. This can be achieved by eating a healthy diet that includes fruits, vegetables, lean protein, and whole grains. Exercise is also important for weight loss, as it helps to burn calories and increase muscle mass.

In contrast, reducing body fat in a healthy way can involve building muscle through strength training and eating a balanced diet. It is important to consume adequate amounts of protein to build muscle while reducing overall calorie intake to promote fat loss.

The following table highlights the major differences between Obesity and Fat −





Obesity is more of a medical term which refers to being grossly fat.

Fat is a colloquial term which refers to being plump of heavy. It is also used in several idioms such as "chew the fat" and "fat chance".


To be categorized as obese, a BMI score of at least 30 is needed.

Being fat is often merely visually perceived.

Good and Bad

Obesity does not have various definitions and it is basically perceived as unhealthy.

There are good and bad as well as saturated and unsaturated fats. Moreover, being "fat" such as "fat land" refers to fertility or being rich.


Obesity is generally applied to humans.

Fat can be utilized when talking about animals as well as plants.

Food Nutrient

Obesity is far from being viewed as something nourishing since it is a disease.

Fats can be food nutrients.


Antonym of obesity is "emaciated" or "anorexia". Evidently, the antonym of the colloquial term is less serious and varied.

Antonym of fat is "thinness". The other antonyms are "clever" and "barren".

Greasy Substance

"obesity" is mainly understood as being heavy or large.

"fat" is also commonly known as a greasy substance.


In summary, while obesity and fat are often used interchangeably, there is a significant difference between the two. Fat is a natural substance found in the body that serves several critical functions, while obesity is a medical condition that occurs when a person has an excessive amount of body fat that negatively impacts their health.

Understanding the difference between the two is essential for managing one's weight and overall health.

Updated on: 19-Apr-2023


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