What are the causes of obesity?

Table of Contents

Obesity is an epidemic that affects millions of people worldwide. In this article, we will discuss what are the causes of obesity and how to prevent it.

Obesity is one of the biggest problems facing our society today. It affects people from all walks of life and ages. Many factors contribute to being obese, including genetics, diet, lack of exercise, etc. But what are the leading causes? And how do we fix them? This blog post looks at these questions.

Key Takeaways:

  • Genetic factors, sedentary lifestyle, unhealthy eating habits, and certain medical conditions contribute to obesity.
  • Consuming high-calorie, processed foods and sugary drinks can lead to weight gain.
  • Lack of physical activity and spending too much time sitting can contribute to obesity.
  • Hormonal imbalances, certain medications, and mental health issues can also cause weight gain.
  • Addressing the underlying causes of obesity through a balanced diet, regular exercise, and lifestyle changes is crucial for weight management.

What is Obesity?

Obesity is an intricate illness that involves an excessive amount of fat. Obesity isn’t just about cosmetics. It’s a medical issue that can increase the chance of developing other diseases and health issues, including diabetes, heart disease, high blood pressure, and cancers.

There are many causes why certain people struggle to lose weight. Most of the time, obesity is caused by genetic, physiological, and environmental influences, along with eating habits, physical activity, and workout options.

The positive side is that even slight weight loss can help improve or reduce the health issues associated with being overweight. Healthy eating, more physical activity, and behavioral changes can aid in losing weight. Weight-loss medications and prescription medication are other options to treat weight gain.

What is the difference between obesity and overweight?

What is the difference between obesity and overweight? What are the causes of obesity?

Definitions of the word “obesity” are different by the definitions. In general, the terms overweight and obesity refer to a body higher weight than is healthy. Obesity is a persistent condition that is characterized by an excess of fat in the body. Some amount of fat is required to store energy, insulation from heat, shock absorption, and other purposes.

Body mass index best defines obesity. A person’s weight and height determine their weight and body mass. BMI, or body mass index (BMI), is the sum of the person’s weight of kg (kg) per meter of height (m) multiplied by (more details will be provided in the following article). Because BMI measures body weight relative to height, it has an extremely strong correlation between it and the total amount of body fat for adults. If an adult with a BMI between 25-29.9 is considered overweight, while anyone with more than 30 BMI is obese. Someone with a BMI of 18.5-24.9 is considered to be average weight. Morbidly obese (significantly overweight) if their BMI exceeds 40.

How common is the issue of obesity?

Obesity is at epidemic levels within the United States. Two-thirds of American adults are obese or overweight, and one-third of Americans are overweight. The rate of obesity among children has risen dramatically. Also, obesity is increasing dramatically across the globe, and the prevalence of obesity has nearly doubled between the year 1991 until 1998. In 2015, more than 40% of the adult population was overweight within the U.S.

Weight Gain, Obesity & Cancer Risk

Obesity is a well-known risk cause for many chronic diseases, including heart disease and diabetes. Obesity may also be associated with an increased risk of developing cancers in particular. To better understand the impact of weight increase on cancer risk, researchers conducted 2007 an analysis of numerous studies published in medical journals, which describe 282,137 cancer cases. Researchers wanted to determine whether weight gain could impact the risk of developing certain types of cancer.


BMI, also known as the Body Mass Index (BMI), is frequently used to identify overweight. To calculate it, BMI Add weight by 703, divide with height inches and divide the result by inches. Or split the weight of a kilogram by the height measured in meters.

BMIStatus of weight
Below 18.5Underweight
30.0 and aboveObesity

Asians with a BMI with an age of 23 or above is a higher risk of health issues.

For most people, BMI gives a fair estimation of body fat. It is a reasonable estimate. However, BMI doesn’t directly gauge body fat; some individuals, like muscular athletes, might be overweight. BMI in the obesity category, even when they don’t have excess body weight.

Many doctors also gauge the waist circumference of a patient to guide treatments. Health issues related to weight are more prevalent in males with a waist measurement of over 40 inches (102 centimeters) and women with an average waist measurement of 35 inches (89 centimeters).

When should you see a doctor?

If you’re worried about your weight, or other weight-related health issues, consult your doctor about managing obesity. Both you and your physician will evaluate the health risks you face and discuss the options for losing weight.


There are behavioral, genetic, and hormonal effects on body weight. It is more likely to be caused by obesity when you consume excess calories through your normal activities and workouts. The body stores this extra energy as fat.

In the United States, most people’s diets are high in calories, often from fast food and drinks high. Overweight people may consume more calories before feeling full, feel hungry earlier, or eat more because of anxiety or stress.

Many people in Western countries have less physically demanding jobs, so they don’t burn more calories while working. Even everyday activities require fewer calories due to modern conveniences like remote controls and escalators, online shopping, or drive-through bank.

Risk factors

Frequent reasons for obesity

The balance between calories consumed and energy consumption determines one’s weight. If a person consumes more calories than is used (metabolizes), the individual gains weight (the body stores excess energy in fat). If someone eats fewer calories than what they can metabolize, they are likely to lose weight. The most frequent reasons for obesity are overeating and inactivity. In the end, bodyweight results from metabolism, genetics, environment, behavior, and culture.

Obesity typically results from a combination of factors and causes:

Influences and inheritance from family members

The genes you inherited from your parents can influence the amount of body fat you store and its location. Genetics can also affect how well your body transforms food into energy and how your body manages your appetite and how you burn calories when exercising.

Obesity runs within families. It’s not only due to the genes that they share. Family members are also likely to have similar food and exercise habits.

Lifestyle choices

Unhealthy Eating Habits
  • An unhealthy eating habit. A diet packed with calories, deficient in vegetables and fruits, stuffed with fast food, and packed with beverages high in calories and large portions can lead to weight growth.
  • Calories from liquids. People can drink numerous calories without feeling full, particularly the calories from alcohol. Other drinks high in calories, like sugar-sweetened soft drinks, may result in significant weight gain.
  • Inactivity. If you have an active lifestyle, it is easy to consume more calories throughout the day than what you use with regular exercise and daily routine. Using a computer, tablet, and smartphone screens is a type of passive. The amount of time spent on the screen is closely connected to weight growth.

Certain illnesses and medicines

For some obese individuals, weight gain can be traced to medical reasons like Prader-Willi syndrome, Cushing syndrome, and other ailments. Health issues, like arthritis, may cause a decrease in activity, leading to weight gain.

Certain medications can cause weight gain if you don’t adjust your diet or exercise. The pills are antidepressants and anti-seizure medicines and diabetes medicines and antipsychotic drugs and beta-blockers, and steroids.

Economic and social concerns

Economic and social factors contribute to weight gain. It is hard to avoid obesity when you don’t have secure places to exercise or walk. Also, you might not have been taught the right ways of cooking or might not have access to healthier food choices. Furthermore, those you interact with can affect your weight, and you’re more likely to gain weight when you have close family members or friends who are overweight.


Obesity can happen at any time, even in infants. As you age, hormonal changes and an inactive lifestyle can make you more likely to be overweight. Furthermore, the muscle mass mass in your body is likely to decrease as you age. In general, a decrease in muscle mass results in a decline in metabolic rate. This can also reduce calorie demands and may make it difficult to stay off extra weight. If you’re not conscious of the food you consume and are increasingly physically active as you age, you’ll probably gain weight.

Physical inactivity

People who are sedentary consume fewer calories than those who exercise. The National Health and Nutrition Examination Survey (NHANES) found strong correlations of physical activity with weight increase for both genders.


The excess of food can cause weight gain, mainly when you eat is rich in fat. Foods with high levels of calories and high in sugar (for instance, fast foods, such as fried foods and sweets) contain high energy density (foods that contain a significant amount of calories for a relatively small quantity of food). Studies on epidemiology have proven that diets high in fat can contribute to weight growth.


One will be more likely to become obese when both parents are overweight. Genetics can affect the hormones involved in the regulation of fat. For instance, one reason for obesity that is genetic is the deficiency of leptin. Leptin is the name of a hormone created by fat cells and the placenta. Leptin regulates weight by signaling the brain to reduce food intake when fat stores in the body are overly large. If for any reason, your body does not make enough leptin or can’t signal to the brain to reduce its consumption, this control goes away, and obesity develops. Leptin replacement as a method of treating obesity is being investigated.

Carbohydrate consumption

It raises blood glucose levels. However, there aren’t any clear links between carbohydrate intake and body fat accumulation. It causes the release of insulin which stimulates muscle cells to take up glucose for energy production. Insulin promotes the formation of new body cells by stimulating cell division and causing them to grow larger. The increased size of these cells leads to an increase in body fat.

The frequency of your eating

The relation between eating frequency with weight loss is a bit controversial. Eating less frequently may help reduce body fat. However, there are conflicting results regarding how much less regularly someone should eat. Some studies indicate that eating less frequently does not affect weight loss as other methods. Other studies show that eating less often may be better for your health. 


The medications that cause weight gain comprise certain antidepressants (medications used to treat depression) and anticonvulsants. Medication can be a significant factor in weight gain or loss. Some medications cause weight gain, while others cause weight loss. However, if you notice any changes in your body shape, talk to your doctor immediately.

Psychological reasons

Some people’s emotional states affect their eating habits. People tend to eat more when they feel emotions like sadness, boredom, stress, or even anger. While most overweight individuals have fewer psychological problems than normal-weight individuals, approximately 30% of those who seek treatment for severe issues with weight have problems with excessive eating.


Like hyperthyroidism, insulin resistance, polycystic ovary syndrome, and Cushing’s disease can also contribute to weight gain. Certain diseases, like Prader-Willi Syndrome, can cause the development of obesity.

Social problems

There is a connection between obesity and social issues. The lack of funds to purchase healthy food items or safe areas for exercise or walking can increase the likelihood of being overweight.

The pregnancy

Weight gain is average during pregnancy. Overweight women may find it difficult to shed after the child is born. Weight gain could contribute to the development of overweight in women.

Smoking less

Quitting smoking is typically linked to weight growth. It may cause sufficient weight gain for some individuals to qualify as obese. This is often the case when people turn to food to cope with withdrawal symptoms from smoking. In the long term, quitting smoking cigarettes is still a better advantage to your health than continuing smoking. A doctor can help avoid weight gain after having quit smoking.

Sleep deprivation

Not getting enough sleep or too much sleep could trigger changes in hormones that boost appetite. It is also possible to crave high in carbohydrates and calories, leading to weight growth.


Many external factors which affect mood and well-being can contribute to weight gain. People are more likely to consume more calories food items when they are in stressful situations.

The microbiome

Your gut bacteria are influenced by the food you eat and could cause weight gain or difficulties in losing weight.

If you don’t have any of the risk factors listed above, it doesn’t mean you’re likely to become obese. It is possible to counteract the majority of risks by eating a healthy diet, exercising regularly and exercising, and changing your behavior.


People who are overweight tend to experience several grave health issues, which include:

  • Heart strokes and heart disease. Obesity makes you more likely to suffer from high blood pressure and irregular cholesterol levels, risk factors for heart disease and strokes.
  • Typ 2 diabetes. Obesity can affect how the body uses insulin to regulate glucose levels in the blood. This can increase the chance of developing insulin resistance and the development of diabetes.
  • Certain types of cancer. Obesity may increase the chance of developing cancer in the uterus and cervix, the ovary, endometrium, breast, colon, rectum, gallbladder, liver, esophagus, pancreas and kidney, and prostate.
  • Digestive issues. Obesity increases the chances of developing heartburn, gallbladder problems, and liver disorders.
  • Sleep Apnea. People with obesity are more likely to suffer from sleep apnea. It is a severe condition where breathing ceases and resumes while sleeping.
  • Osteoarthritis. Obesity puts more stress on joints bearing weight as well as causing inflammation throughout the body. These causes can lead to problems like osteoarthritis.
  • COVID-19 severe symptoms. Obesity can increase the chance of experiencing severe symptoms should you be infected by the virus that causes coronavirus infection in 2019 (COVID-19). Patients who suffer from severe symptoms of COVID-19 might require care within intensive care facilities or even mechanical support to breathe.

Life quality

Obesity may affect the general quality of your life. You might not be able to perform exercises that you once enjoyed. It is possible to avoid public spaces. Obese people may face discrimination.

Other weight-related issues that could impact your life quality are:

  • Depression
  • Disability
  • Shame and guilt
  • Social isolation
  • Lower work achievement

Obesity Facts

Within the U.S., obesity has been on the rise to epidemic proportions.


Research shows that there is a link between genes and obesity. Several gene variations may increase the chances of becoming overweight or obese. These include the FTO gene variation and MC4R gene variation. The FTO gene variation increases the chance of gaining weight and obesity. MC4R gene variation decreases the likelihood of gaining weight and obesity but does not eliminate this possibility.


Adults who exercise regularly tend to be healthier and slimmer than those who do not. Exercise helps people lose weight and maintain their health. However, many adults find it hard to keep up with regular physical activity because they lack time or motivation. Also, overeating food can lead to obesity if one does not follow a healthy diet plan. This includes foods that contain empty calories, such as processed foods and sugar-sweetened beverages.


Some studies show that inactivity contributes to obesity. People who spend most of their day sitting down are more prone to obesity. This is because a sedentary lifestyle leads to decreased energy expenditure and an increase in fat storage. It is recommended that adults should get at least 150 minutes of moderate-intensity aerobic activity per week.


Overweight and obesity are two different terms used to describe excess body fat. A person is considered overweight if they weigh more than usual for height. Obesity occurs when a person’s body mass index exceeds 30 kg/m2. BMI is calculated by dividing a person’s weight in kilograms by their height in meters squared.

Health risks.

Being overweight or obese increases the risk of suffering from various diseases, including type 2 diabetes, cardiovascular disease, certain cancers, arthritis, asthma, digestive disorders, infertility, sleep apnea, and some forms of dementia.

The cost of being overweight or obese.

In addition to the personal costs of having excess weight, the financial burden of dealing with obesity also significantly contributes to society. According to estimates, the total annual cost of obesity in the United States was $147 billion in 2011. That amount grew to over $210 billion in 2016.

Treatment options.

Doctors usually recommend dietary changes and increased physical activities to help individuals control their weight. Losing weight through dieting alone is difficult. Therefore, doctors often suggest that patients try combining dieting with other ways to lose weight. Weight loss surgery is another option for severely obese patients.

How is obesity defined?

According to the World Health Organization, obesity is “abnormal or excessive fat accumulation that presents a health risk.” WHO defines overweight as 25% above ideal body weight and obesity as 30% above ideal body weight. Ideal body weight is determined using the following formula:

Body mass index weight in kilograms/square of height in meters

Obese people have a high percentage of body fat compared to lean people. Body fat is measured using either a caliper or bioelectrical impedance analysis. BIA involves measuring the electrical resistance of the body. A machine then uses these measurements to calculate the body fat percentage.

Is obesity reversible?

Yes, obesity is generally reversible. Several factors determine whether someone becomes overweight or obese. Genetics plays a role, as well as lifestyle habits. You will naturally lose weight if you combine good nutrition and regular physical activities. You can also reduce calorie intake and increase physical activity to achieve long-term weight loss goals.

What are the symptoms of obesity?

If you have been diagnosed with obesity, you might notice some of the following signs and symptoms:

Obesity Symptoms
Fat around the belly
Difficulty breathing while exercising
Increased blood pressure
High cholesterol levels
Erectile dysfunction
Sleep apnea
Heart attacks
Other conditions linked to obesity include:
Gallbladder disease
Rheumatoid arthritis
Liver problems
Kidney stones
Prostate enlargement
Type 2 Diabetes
Some of the most common complications associated with obesity include:
Coronary artery disease
Congestive heart failure
Breast cancer
Mental illness

Are there health risk factors that come with being overweight?

Being overweight affects one person and everyone who comes into contact with them. In fact, according to statistics from the World Health Organization (WHO), approximately 2 billion adults worldwide were obese in 2016. And if current trends continue, by 2030, WHO estimates there could be 1.4 billion people living with diabetes. People with a BMI of more than 40 are less likely to live duration. Obesity can also increase the likelihood of developing many chronic diseases, which include the following:

Insulin resistance

It occurs when insulin is less efficient for transporting sugar from the bloodstream into muscles and liver cells. This leads to high blood sugars and eventually diabetes. Fat cells resist insulin because they store excess calories as triglycerides instead of releasing them through metabolism. However, both types of cells may become insulin-resistant if too much sugar accumulates in their cytoplasm. So long as the pancreas can produce sufficient insulin to counter this resistance blood, sugar levels are normal.

Typ 2 diabetes

Type 2 diabetes mellitus (T2DM) was associated with both abdominal fat distribution and a longer duration of obesity.

High blood pressure (hypertension)

Hypertension is common among overweight people. A Norwegian study showed that gaining weight could raise the blood pressure for females more significantly than for men.

Heart disease. 

Overweight and obesity are known to cause hypertension and coronary heart disease. The combination of these two conditions increases the risk of stroke.


Obesity has been linked to increased risks of colon cancer, breast cancer, endometrial cancer, kidney cancer, gallbladder cancer, esophageal cancer, pancreatic cancer, thyroid cancer, ovarian cancer, prostate cancer, stomach cancer, skin cancers, lymphoma, multiple myeloma, bone cancer, and leukemia.

How do I know if I am at risk of becoming obese?

f I am at risk of becoming obese?

The most important thing to remember is that not all people who gain weight are unhealthy. There are different reasons why people gain weight. Some people need to eat certain foods due to medical issues such as anorexia or bulimia, while others may have a genetic predisposition towards being overweight.

However, it is possible to identify individuals at risk of becoming overweight. These include the following:

  • People who are genetically predisposed to obesity
  • Those who are underweight or malnourished
  • Children who are growing up in families where parents are overweight
  • Adolescents who are trying to lose weight
  • Pregnant women who are gaining weight during pregnancy
  • People over 65 years old who are overweight
  • Physically inactive people
  • People who smoke cigarettes
  • People with mental health problems
  • Some medications used to treat depression and anxiety may lead to weight gain.
  • If you think you might be experiencing any of the symptoms above, it would be wise to seek professional help before it becomes a problem.
  • In addition to this, some other factors can contribute to obesity. These include:
  • Lack of sleep. This can occur due to stress, poor diet, or lack of exercise.
  • Poor nutrition. Not eating enough healthy food can lead to overeating later on.
  • Eating late at night. Eating after 8 pm can lead to a higher calorie intake.
  • Not taking time to relax. People who don’t take time out to rest will find it difficult to cope with stress and work effectively throughout the day.
  • Excessive alcohol consumption. Alcohol can make people feel hungry and eat more, so always moderate your drinking habits.
  • Having a stressful job. Stressful jobs can lead to overeating and a lack of physical activity.

What are the other contributing factors with overweight?

  • Ethnicity. Factors affecting ethnicity can affect the age at which onset occurs and the speed at which weight gain occurs. Black women and Hispanic women are more likely to have weight gain later in life than Caucasians and Asians, and age-adjusted obesity rates are higher among these two groups. Black non-Hispanic men and Hispanic males have a greater overweight rate than non-Hispanic white males. However, the disparity in prevalence is much less than that of women.
  • Childhood weight. A person’s weight during childhood, teenage years, and early adulthood can also affect the progression of obesity in adulthood. Thus, reducing the incidence of childhood obesity is among the areas of focus to fight obesity. For instance, being overweight in the:
    • early 20s was connected to a high rate of overweight by 35.
    • Later childhood years is a strong indicator of adult obesity, particularly in the case of parents who are obese.
    • teenage years can be an increased predictor of being overweight.
  • Hormones. Women can gain weight, particularly in situations like pregnancies, menopause, and oral contraceptives. With the advent of estrogen pills with lower doses, weight gain has not been as risky.

Latest Science-Based Data

1. Joint international consensus statement for ending stigma of obesity

  • Published on: March 4, 2020
  • Abstract: This research focuses on the social stigma faced by people with obesity. It emphasizes that weight stigma can cause physical and psychological harm, and that affected individuals are less likely to receive adequate care. The study calls for education about weight stigma to facilitate a new public narrative about obesity, coherent with modern scientific knowledge.
  • Read the full text

2. Causal relationships between obesity and the leading causes of death in women and men

  • Published on: October 1, 2019
  • Abstract: This study investigates the causal implications of obesity traits on non-communicable diseases and explores sex-specific differences in these causal effects. It shows that obesity traits have an etiological role in the majority of the leading global causes of death.
  • Read the full text

3. A comprehensive diagnostic approach to detect underlying causes of obesity in adults

  • Published on: March 1, 2019
  • Abstract: This research emphasizes the importance of adequate diagnostics to detect potential underlying diseases and contributing factors to obesity. It provides practical recommendations to identify diseases such as monogenetic or syndromic obesity, hypothyroidism, and others, as well as common contributing factors like medication and mental factors.
  • Read the full text

4. Genetic and Syndromic Causes of Obesity and its Management

  • Published on: June 1, 2018
  • Abstract: Not available, but this study seems to focus on the genetic and syndromic causes of obesity and discusses their management.
  • Read more


What are the main causes of obesity?

The main causes of obesity include overeating, lack of physical activity, genetic factors, and certain medical conditions.

Can genetics contribute to obesity?

Yes, genetics can play a role in obesity. Certain genes can increase a person’s susceptibility to weight gain.

How does a sedentary lifestyle contribute to obesity?

A sedentary lifestyle, with little physical activity, can lead to weight gain and obesity due to fewer calories being burned.

Are there any psychological factors that contribute to obesity?

Psychological factors such as stress, emotional eating, and certain mental health conditions can contribute to obesity.

Can certain medications cause weight gain and obesity?

Yes, certain medications like antidepressants, corticosteroids, and antipsychotics may lead to weight gain and contribute to obesity.


Obesity, a growing concern in today’s society, is caused by a combination of factors that go beyond simply overeating. In our article “What Are the Causes of Obesity,” we delve into the various reasons behind this epidemic. From sedentary lifestyles and unhealthy eating habits to genetic predispositions and environmental influences, the causes of obesity are multifaceted and interconnected.

But let’s not dwell on the seriousness of the issue for too long! Instead, let’s take a lighthearted approach to understanding the causes of obesity. Imagine you’re at a buffet, and the desserts are calling your name. As you fill your plate with delectable treats, you wonder, “What are the causes of obesity?” You chuckle to yourself, knowing that it’s not just about that extra slice of cake or the irresistible fried chicken.

In our article, we uncover the hidden culprits behind obesity. We explore how our modern sedentary lifestyles, filled with binge-watching Netflix and endless hours spent sitting at desks, contribute to weight gain. We also discuss how our love affair with fast food and sugary drinks significantly expands waistlines.

But it’s not all doom and gloom! We also touch on the genetics of obesity, as some individuals may have a predisposition to gain weight. And let’s not forget about the impact of our environment, from food marketing tactics to the lack of accessible healthy options in certain areas.

So, if you’ve ever wondered, “What are the causes of obesity?” our article has covered you. It’s time to dive deeper into this complex issue, laugh at some relatable moments, and better understand why obesity is on the rise.

Now, I challenge you to take action! Share this article with your friends, family, and even that person who always seems to have a bag of chips in hand. Let’s spread awareness and encourage healthier choices together. Remember, knowledge is power, and by understanding the causes of obesity, we can make informed decisions and lead healthier lives. So go ahead, engage with the article, and let’s tackle obesity head-on!