Obesity vs. Overweight: What Is The Difference?

by Ahmed Zayed, MD on May 29, 2019
Last updated on May 23, 2021

Obesity and overweight are two terms that are often used in close relation to each other. While both of these terms are used to describe excess weight in the human body, it is important to understand that there are some important differences between the two classifications, as they are often referred to.

silhouette of a man's body from obese to ideal weight

Being overweight or obese used to be looked upon as a behavioral issue, but in the modern world, scientists have started to view obesity as an actual disease (1) that impair the body’s ability to function normally, leading to the development of disease, as well as a poorer quality of life. Overweight, on the other hand, is rather considered a stepping stone toward obesity.

Understanding the difference between obesity and overweight is important, along with the implications imposed by both of these conditions. This can help you determine what type of protocols you would ultimately have to implement if you are looking to reduce the risks that you are facing and achieve a healthier lifestyle.

How Is Your BMI Determined?

Let’s start by looking at how you can determine if you are at a healthy weight, overweight, or if you are currently considered to be obese.

These categories are measured by what is commonly referred to as your BMI. The term “BMI” stands for Body Mass Index and essentially provides you with your weight in kg/m2. Different ranges of BMI fall under various categories – you would need to calculate your current BMI in order to determine if you are actually at a healthy weight, or if you are carrying too much weight around.

The calculation is relatively simple, and you can easily do it on your own. If you find it too difficult, however, then there are many online calculators that you can use to help you determine what your current BMI is.

To calculate your BMI, you will need to factors that are both taken into account during this particular calculation:

  1. Your weight – this is the weight you see when you step onto the bathroom scale and should be in kilograms for the purpose of calculating your BMI. If your bathroom scale provides your weight in pounds, then simply convert your weight in pounds to kilograms.
  2. Your height – you will also need to know your height. The BMI calculation requires your height in meters. If your measuring tape provides measurements in inches, you will have to convert your height in inches to meters.

Once you have both of these values ready, the calculation is simple: kg/m2 – that is your weight in kilograms divided by your height, which should be in meters squared.

For example, if you weigh 85 kilograms and your height is 1.7 meters, then your BMI would be 29.4. If you weigh 75 kilograms and your height is 1.75 meters, then your BMI is 24.5.

A normal or “healthy” weight is classified between the BMI ranges of 18.5 and 24.9. When your BMI strikes below 18.5, then you are considered to be underweight. If your BMI calculates to 25 or above, then you have too much excess weight in your body, and you might be at a higher risk for certain diseases and health conditions.

What Does It Mean To Be Overweight?

Overweight is a term that is used to describe a person with a BMI that ranges from 25up to 29.9. At this point, it means there is excess weight in the individual’s body and that they are not at a healthy weight, but it does not mean they are exposed to all of the life-threatening conditions that are associated with carrying a significant amount of extra weight. Still, this does not mean you are out of the red zone in terms of diseases associated with excess weight if you simply ensure you maintain your BMI in this range.

At the point of being overweight, it is often recommended that preventative measures be put into place in order to avoid the individual from leaping toward obesity. As BMI increases, so does the risks associated with excess weight. When the right protocols are in place, many people will find that it is relatively easy for them to lose their excess weight while they are overweight, instead of waiting until obesity sets in before they take appropriate action.

Treatment for overweight usually includes a series of changes to a person’s lifestyle. This may consist of dietary changes so that the individual consumes a more balanced meal plan that contains healthier food options, along with the elimination of foods that are currently considered the culprits in their weight gain. An exercise program is usually also implemented to help the individual burn calories on a regular basis, which initiated the weight loss process and helps them get their BMI down to under 25.

According to data released by the World Health Organization (2), an estimated 39% of adults around the world are overweight, with a BMI between 25 and 29.9. This equates to over 1.25 billion individuals over the age of 18. Among children, the statistics for being overweight is just as alarming.

What Does It Mean To Be Obese?

Obesity is considered a disease today and is much more serious than being overweight. You are classified as obese when your BMI is 30 or higher. In cases where your BMI may reach higher than 35, you would be classified as morbidly obese. An estimated 650 million adults around the world are obese, calculating to around 13% of the global adult population.

Obesity is currently classified as the second most alarming cause of death that is preventable, falling just behind tobacco, which takes the number one spot. It is estimated that approximately 300,000 people die each year in the United States as a complication of their obesity (3).

Obesity is considered a major contributor to many diseases that are life-threatening and leading to thousands of deaths each year that are considered premature. Type 2 diabetes is certainly one of the most important risks imposed by obesity, but there are many other complications that may develop in the body as a result of the excess weight. Some of these conditions and diseases include (4):

  • High blood pressure (hypertension)
  • Osteoarthritis
  • Gallstones
  • Respiratory conditions like asthma, as well as sleep apnea
  • Cardiovascular diseases
  • Gout

People who are obese are also more likely to have a stroke. The risk of a heart attack is also increased with obesity.

Treatments for obesity are often more invasive and intense compared to options provided to individuals who are overweight and have not yet reached the BMI of obesity.

Dietary changes and the implementation of an exercise program are usually two of the first options implemented to assist in the treatment of obesity. For many people, however, this may pose difficulty or not be a completely effective approach. In cases where the individual is already suffering due to their excessive weight, additional measures and treatment procedures may be advisable.

There are certain types of medication that can be prescribed to a person to assist in reducing their body weight. Xenical is a particularly popular option, but alternatives also exist. This type of medication usually helps to reduce the individual’s appetite, leading to a reduction in their calorie intake. This can assist the individual in following a calorie deficit diet, which can lead to successful weight loss.

In more serious cases, a surgical procedure may be advised to the individual, but this is often only considered the last resort if other methods have not provided effective results. There are different types of surgeries that may help with the treatment of obesity in a person. A gastric sleeve or the use of a gastric band is a common option. Some individuals may also opt for a gastric bypass procedure. There are, however, some risks associated with these procedures that a person will first need to take into consideration.

When Is BMI Not Used?

In most cases for a healthy individual, BMI will be used to determine if they are at a healthy weight, underweight, overweight, or perhaps obese. Even though BMI is the most common method used to determine the risks imposed by a specific individual’s current total body weight, it should be noted that there are cases where BMI does not provide an accurate overview of how a person’s weight is impacting their health.

The reason why BMI is not always the recommended classification system to be used is that this calculation only takes into account a person’s body weight, along with their height. It does not account for any other factors (5).

There is a couple of cases where BMI would usually not be used in this type of scenario. In particular, these are the specific scenarios where a person’s BMI would not be considered a crucial factor:

  • Athletes – when it comes to athletes and especially bodybuilders, it is important to consider the fact that lean muscle mass can cause weight gain. When BMI is used on a bodybuilder, it may classify the person as being overweight or even obese, even though their body fat percentage is on the low side. When a body builder’s BMI is higher than what is considered “normal,” it does not necessarily mean they are exposed to the same risks as the “average” individual that would have a similar BMI caused by fat in the body.
  • Pregnant women – in pregnant women, BMI does not take into account the particular changes that the female body goes through during pregnancy. Women tend to gain weight during pregnancy – partly as a result of the unborn baby that is growing inside of them. Thus, again, BMI would not be an appropriate measurement of the woman’s weight on her overall health.
  • Young children – In young children, muscle development has not been completed yet. They are still growing and need to develop to the state where their muscles can be considered “completely developed.” In this scenario, BMI would not take this into account. This can often lead to a reading that the child is underweight, even though they might be at an appropriate weight for their age.
  • Elderly – The elderly may also calculate a low BMI that would classify them as underweight when they are at an appropriate weight. With the elderly, it is important to take into consideration the fact that muscle mass tends to decline with age, and this can yield a lower body weight.


While overweight and obese both refers to excess weight in the human body, it is important to understand that obesity is a much more dangerous condition and is now considered a disease. Obesity exposes the body to a number of risks, ranging from heart disease and diabetes to cancer. Treatments available to individuals vary depending on their BMI, with more invasive treatment procedures sometimes recommended to reduce the risks in those with a higher BMI.


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