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Reviewed by
Dr Joseph Santos
Medical Director
Last reviewed
Nov 11, 2022


Obesity is a complex disease involving an excessive amount of body fat. Obesity isn't just a cosmetic concern. It's a medical problem that increases the risk of other diseases and health problems, such as heart disease, diabetes, high blood pressure and certain cancers.

There are many reasons why some people have difficulty losing weight. Up to 80% of weight is determined by your genes.[6] For some with biological weight influences, diets and exercise won’t always lead to results.

The good news is that even modest weight loss can improve or prevent the health problems associated with obesity. A healthier diet, increased physical activity and behavior changes can help you lose weight. Prescription medications and weight-loss procedures are additional options for treating obesity.


Body mass index (BMI) is often used to diagnose obesity. To calculate BMI, multiply weight in pounds by 703, divide by height in inches and then divide again by height in inches. Or divide weight in kilograms by height in meters squared.


Asians with BMI of 23 or higher may have an increased risk of health problems.

For most people, BMI provides a reasonable estimate of body fat. However, BMI doesn't directly measure body fat, so some people, such as muscular athletes, may have a BMI in the obesity category even though they don't have excess body fat.

Many doctors also measure a person's waist circumference to help guide treatment decisions. Weight-related health problems are more common in men with a waist circumference over 40 inches (102 centimeters) and in women with a waist measurement over 35 inches (89 centimeters).


Many factors can contribute to excess weight gain including eating patterns, physical activity levels, and sleep routines. Social determinants of health, genetics, and taking certain medications also play a role.

Food, Activity, and Sleep

Eating and physical activity patterns, insufficient sleep and several other factors influence excess weight gain.

In our modern lives, there are more energy-dense foods available which are often higher in sugar and fat. These foods are often cheaper, easier to access and more convenient for people leading busy lives.

Appetite signals and hormones

Chemical sensors in our blood called hormones give us a signal when we’re hungry, so we eat, and when we’re full, so we stop. For people who are obese, these hormones don’t work as they should, meaning you have to eat more before you feel full6. These hormones make it harder for you to lose weight and keep it off.


Your genes play a big role in whether you will develop obesity. Studies on twins who grew up in different homes found their genes had a bigger impact on whether they had a higher BMI8. In this study, they found environmental factors had little impact. This may sound disheartening, but it doesn’t mean you should give up on losing weight. It just shows that obesity is not your fault.

Environmental Factors

Where you live can have a direct impact on your weight. Advertising, access to fresh fruit and vegetables and support from your government, workplace and community can affect the food choices you make and how much exercise you’re able to do5.For example, in Australia, 38% of adults in the lowest socioeconomic areas were obese, compared to 24% in the highest.

For example, in Australia, 38% of adults in the lowest socioeconomic areas were obese, compared to 24% in the highest.9

Many people who live in Western countries now have jobs that are much less physically demanding, so they don't tend to burn as many calories at work. Even daily activities use fewer calories, courtesy of conveniences such as remote controls, escalators, online shopping and drive-through banks.

Illnesses and Medications

Some illnesses, such as Cushing’s disease, may lead to obesity or weight gain. Drugs such as steroids and some antidepressants may also cause weight gain. Research continues on the role of other factors such as chemical exposures and the role of the microbiome. If you suspect your medicine is contributing to your weight gain, it’s important not to stop taking them. Talk to your doctor about what the best approach is in your situation.


But don't lose hope or think that you have to manage obesity on your own. You can partner with your doctor or other healthcare professionals and control the disease of obesity and reap the health benefits that come with weight loss.

You can consult with a doctor online for obesity examination. To diagnose obesity, your doctor will typically want to examine your physical condition, including your BMI, waist circumference, heart rate and blood pressure. If you have known health problems, your doctor will evaluate them in your health questionaire. Your doctor will also check for other possible health problems, such as high blood pressure, high cholesterol, underactive thyroid, liver problems and diabetes.

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There are lots of ways to treat obesity and manage weight. Each obesity treatment works in a different way and can be done on its own or combined with other treatments. With the help of obesity care providers, you can find an obesity treatment and create an obesity care plan specifically for you. Listed below are some scientifically-proven obesity treatment options to manage weight

Option #1: Transition to healthier ways of eating

Your doctor or dietitian will take how you eat into consideration when creating your obesity care plan. Some of the things that you can look at together include:

  • Time. Is there a specific time of day that you're most at risk of overeating or eating unhealthy food?
  • Place. Where do you normally eat? 
  • Emotions. Do you overeat or eat unhealthy food when you feel a certain way? For example, when you feel tired, stressed, or sad? 
  • Feeling full. How do you experience the feeling of fullness after a meal?

These questions provide clues about what's making you gain weight or preventing you from losing weight. Your doctor can then help you transition to healthier ways of eating and having a more sustainable relationship with food.

Option #2: More physical activity

Moving more and using more energy is another obesity treatment option. Whether or not it results in weight loss, physical activity can also improve many aspects of your health.

Option #3: Behavioural therapy

Since our body and mind are deeply connected, behavioural therapy is an obesity treatment option that takes this connection into account. Behavioural therapy are programmes that help patients reach their behavioural or health goals.

Option #4: Meal replacements / low energy diet

Meal replacements are calorie-controlled products that contain essential nutrients, vitamins, and minerals. They're usually high in protein and low in fat and carbohydrates.

Meal replacements replace one or more of your daily meals with foods or formulas that provide a specified number of calories (for example, between 800 and 1200 calories a day). Meal replacements can be part of a clinically supervised obesity care plan.

Option #5: Anti-obesity medications

Many different types of anti-obesity medicines have been tested in clinical trials. Anti-obesity medications are obesity treatment options that can work with the biological processes that affect your appetite.

There are different anti-obesity medications available and they work in different ways. Some anti-obesity medications help regulate your appetite and food cravings. These help you eat less and make it easier to change your lifestyle.

Anti-obesity medications can also help prevent weight regain. They do this by managing the way your body responds when you manage weight, such as the constant feeling of hunger. Other medications help you manage weight by changing the way your body absorbs food. For example, these lower the amount of fat that's absorbed by your body.

Option #6: Bariatric surgery

Gastric bypass and other weight-loss surgeries — known collectively as bariatric surgery — involve making changes to your digestive system to help you lose weight. Bariatric surgery is an obesity treatment that can lower your appetite and the amount of food you can comfortably eat in one sitting. They've been shown to change the body's metabolism and hormones, both of which play a major role in how your weight is regulated. For example, the hormonal changes from bariatric surgery work to prevent weight regain.

Is obesity a disease?

This is a very common question and you will get different answers depending on who you ask. In 2013, the American Medical Association1 voted to categorise obesity as a disease. Since then, the Australian andNew Zealand Obesity Society (ANZOS)2 and many other organisations around the world have classified obesity as a disease.

Is obesity genetic?

Most people probably have some genetic predisposition to obesity, depending on their family history and ethnicity. Moving from genetic predisposition to obesity itself generally requires some change in diet, lifestyle, or other environmental factors.

What are the consequences of obesity?

Carrying extra fat leads to serious health consequences such as cardiovascular disease (mainly heart disease and stroke), type 2 diabetes, musculoskeletal disorders like osteoarthritis, and some cancers (endometrial, breast and colon). These conditions cause premature death and substantial disability.

Why is obesity a problem in society?

Like tobacco, obesity causes or is closely linked with a large number of health conditions, including heart disease, stroke, diabetes, high blood pressure, unhealthy cholesterol, asthma, sleep apnea, gallstones, kidney stones, infertility, and as many as 11 types of cancers, including leukemia, breast, and colon cancer and more.

How common is obesity?

Nearly 1 in 3 adults (30.7%) are overweight. More than 1 in 3 men (34.1%) and more than 1 in 4 women (27.5%) are overweight. More than 2 in 5 adults (42.4%) have obesity (including severe obesity). About 1 in 11 adults (9.2%) have severe obesity.

Why is it hard to manage obesity?

There is an evolutionary basis to our current predicament: Our bodies have evolved in a world where high-calorie food has historically been scarce and valuable, with starvation a constant danger. This is one reason obesity is so difficult to treat; our bodies are wired to protect our weight.

How does obesity affect mental health?

Many people with obesity also struggle with mental health. Stigma and discrimination in many areas of your life can lead you to using food as a coping mechanism, which can increase your weight.

How do you know if you have obesity?

A doctor will usually check your weight and height and then determine your Body Mass Index (BMI). It’s a very general measure that helps put you into a weight category: underweight, normal weight, overweight, or obese.

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