Why we get Fat and Become Obese: Causes, Management and Prevention

Overview

This article explains the biological and lifestyle factors that lead to fat gain and obesity, including energy imbalance, hormonal influences, and physical inactivity. It also provides evidence- based strategies for preventing and reducing excess body fat. 

People become obese when they consume more calories than they burn over time, especially through frequent intake of high-calorie foods and low physical activity.

The world health organization (WHO) classifies obesity as a chronic disease arising from complex interaction between genetic predisposition, neurobiology, eating behaviors, access to healthy diet, and the broader environment. 

Based on current scientific studies, Practical strategies such as maintaining a balanced diet, increasing daily activity, adopting sustainable behavioral change are discussed as effective approaches managing body weight.

1.INTRODUCTION

What is body fat?

Body fat can be defined as the quantity of fat tissue in the body. Fat tissue, also called adipose tissue, is the type of connective tissue in the body that stores energy in the form of fat. This body energy storage system is made of fat cells.

Where is fat tissue located?

Fat tissue is found throughout the body in specific locations, and each location has a slightly different role:

·       Under the skin (subcutaneous fat): This is the most visible fat layer. It is found just beneath the skin, especially in the abdomen, thighs, hips, arms, and buttocks. It helps with insulation, cushioning and it gives its external shape.

·        Around internal organs (visceral fat): This fat is found deep inside the abdomen, surrounding organs like liver, kidneys intestines and stomach. It acts as protection, but when it becomes excessive, it is strongly linked to health risks such as heart disease and diabetes.

·       Inside bone marrow (especially yellow bone marrow): Some fat tissue exists in the marrow, especially in adults. It contributes to long-term energy storage and support blood cells production. This fat stores the energy the body can mobilize during periods of high demand such as fasting, starvation or illness.

·       Between muscles: Small amount of fat is stored between muscles groups. This helps with energy supply and some mechanical protection during movement.

·        Around the heart blood vessels and kidneys: This fat surrounds the heart and major blood vessels. It helps protect these structures, but excess amount can affect cardiovascular health.

The rising epidemic of body fat gain and obesity

Over the past few decades, body fat gain, overweight and obesity have become major global concerns, affecting millions of people across all age groups. Once considered a problem limited to high –income counties, excess weight is rapidly increasing in low and middle – income regions, including many parts of Africa.

This shift reflects profound changes in lifestyle, nutrition and daily habits driven by urbanization and modernization. In countries like Rwanda, these changes are becoming increasingly visible, especially in urban areas where dietary patterns and lifestyle behaviors are evolving.

The second Rwanda non – communicable diseases (NCDs) risk factors study showed that the number of obese people in Rwanda increased from 14 % in 2013 to 18.6 % in 2022.

According to the world health organization, global obesity rates have nearly tripled since 1975, making excess body fat a major risk factor for chronic conditions such as Obesity, cardiovascular disease, and type 2 diabetes.

In 2022, approximately 1 in 8 people worldwide were living with obesity. During the same year, about 2.5 billion adults aged 18 years and older were classified as overweight, including 890 million with obesity. This represent 43 percent of the global adult population being overweight and 16% living with obesity.

The trend is equally concerning among younger populations. In the same year, 2022, more than 390 million children and adolescents aged 5 – 19 years were overweight, including 160 million with obesity, while in 2024, an estimated 35 million children under the age of 5 were also affected.

Over the past decades, adult obesity has more than doubled since 1990, and adolescent obesity has increased nearly fourfold, highlighting a rapidly growing global epidemic that requires urgent attention.

Ultimately, the rise in body fat is not just an individual issue, however it is a complex public health challenge shaped by environmental, economic and social factors. Understanding this global context is essential for developing effective strategies to prevent and manage unhealthy weight gain.

2. WHY WE GET FAT OR OBESE?

Obesity develops because of a combination of different factors that influence how the body stores and uses energy. Among those factors, there is biological, behavioral, psychological and environmental and social influences.

Biological Factors contributing to obesity.

Obesity is influenced not only by lifestyle behaviors but also by biological mechanisms that affect appetite, metabolism, and fat storage. Research indicate that genetic factors may contribute approximately 40 – 70 % of an individual’s risk of developing obesity. These biological influences can make weight management difficult, even when healthy lifestyle changes are adopted.

A study published by the National institutes of health explains that more than 400 genes have been associated with obesity. Most cases are polygenic, meaning multiple genes interact to influence hunger, satiety, and body fat distribution.

The study further identifies the FTO gene as one of the strongest genetic contributors linked to increased body mass index (BMX) and higher appetite levels.

According to research from the Harvard T.H. Chan school of public Health, hormonal imbalances also play a critical role in obesity development. Leptin, a hormone produced by fat cells, is responsible for signaling fullness to brain. 

However, many individuals with obesity develop leptin resistance, causing the brain to ignore satiety signals and leading to continued eating. The same research highlight ghrelin, commonly called the "hunger hormone", which can remain elevated after meals and increase appetite.  

A report from the Centers for Disease Control and Prevention says that metabolic differences contribute significantly to obesity. Individual with lower resting metabolic rates or reduced energy expenditure tend to burn fewer calories, increasing the likelihood of excess fat storage.

In addition, chronic stress can elevate cortisol levels, which is associated with increased abdominal fat accumulation. The gut microbiome also influences obesity risk. Variations in gut bacteria affect digestion, nutrient absorption, and metabolism, potentially promoting weight gain.

Furthermore, studies cited by World Health Organization suggest that prenatal and epigenetic factors may predispose individuals to obesity. Maternal obesity or gestational diabetes during pregnancy can alter gene expression in children, increasing their future obesity risk.

Lifestyle and environmental factors which leads to Obesity

Obesity is also caused by a combination of dietary, medical, social and environmental factors. Health central explains that unhealthy food high in sugar, salt and fat are often cheaper, heavily marketed, and easier to access than nutritional foods, increasing the risk of excessive calorie consumption.

Limited access to healthy foods in low- income and rural communities also contribute to unhealthy eating habits. Restaurants, fast- outlets and vending machines frequently provide high – calorie meals and oversized portions, which encourage overeating. In addition, certain medical conditions such as hypothyroidism, Cushing’s syndrome, and polycystic ovary syndrome (PCOS) can contribute to weight gain.

Some medications, including antidepressants and corticosteroid, may also increase body weight as a side effects. Lack of sleep, ageing and hormonal imbalance can also affect metabolism and appetite regulation, making obesity more likely to develop. 

Sleep deprivation, for example, disrupts hormones responsible for hunger and fullness, while aging slows metabolism and increases abdominal fat storage.

There is also the importance of social and environmental factors. Limited access to safe recreational spaces, chronic stress, and increased screen time from modern technology contribute to sedentary lifestyles and unhealthy eating behaviors.

Stress can increase cortisol levels and stimulate overeating, while excessive use of phones, computers and television reduces physical activity.

3. HEALTH CONSEQUENCES OF OBESITY

Obesity Health risks for adults

Excess body fat is not merely a cosmetic concern; it is a major public health issue with far- reaching consequences for individuals and society. Obesity is more than just carrying extra – weight, it is a complex, chronic condition that can significantly affect overall health.

When the body accumulates too much fat, it can trigger inflammation and lead to long - term metabolic changes. These changes interfere with normal body functions and increase the likelihood of developing serious health problems.

The risks become even greater depending on how much excess weight a person carries and how long they have lived with it. Research has consistently shown that obesity in adulthood is closely linked to a wide range of medical conditions, including:

·        1.Hypertension

·        2.Abnormal cholesterol levels such as high triglycerides

·        3.Type 2 diabetes

·       4. Heart disease and stroke

Beyond cardiovascular issues, obesity is also associated with certain types of cancer, gallbladder disease and liver conditions such as fatty liver disease. Other linked problems are respiratory conditions such as asthma and obstructive sleep apnea, pregnancy problems like gestational diabetes, as reported by centers for Disease control and prevention.

Obesity risks in children

Childhood obesity, when not addressed early, can lead to wide range of serious consequences that extend far beyond childhood. One of the most well-known outcomes is the obesity in adulthood, along with mental and emotional impacts, reduced physical performance, academic effects, and other long term health burdens.

childhood obesity is not just a temporary condition; it often continues into adulthood and leads to serious health complication later in life. Research shows that a significant proportion of children who are overweight or obese remain in the same condition as they grow older.

On average, about 40% and in some cases as high as 80%, of these children become or remain overweight and obese in adulthood (Bridger, 2009; Deshmukh- Taskar et al.,2006; Serdula et al.,1993). In addition, obesity tends to run in families.

Children with at least one obese parent have a much higher likelihood of becoming obese by the age of seven, and the risk increases even further when both parents are affected (Reilly, 2005).

Mental health and emotional impacts of childhood obesity:

Children with obesity are more likely to experience low self – confidence and poor body image. Weight-related bulling and stigma ca harm emotional wellbeing and increase social isolation. Obesity may also contribute to attention difficulties and reduced academic performance. Source: word Health organization.

Academic Consequences of childhood Obesity

·        Poor academic performance: Children affected by obesity are more likely to experience weaker school performance and lower academic results than their healthy- weight classmates.

·        Difficulties in cognitive functioning: childhood obesity can negatively influence memory, concentration, problem-solving ability and mental flexibility, making learning activities more challenging.

·        Higher rates of absenteeism: Students with obesity tend to miss school more frequently, often because of health problems associated with obesity such as asthma or diabetes.

·        Lower educational success in the future: Research shows that individuals who were obese during childhood may have reduced chances of completing higher levels of education, including college studies. Source: PubMed Central.

Economic and social impacts of fat gain and obesity

World obesity Federation reports that overweight and obesity have become major public health and economic challenges worldwide. Beyond affecting people’s health and quality of life, obesity also places a heavy financial burden on families, healthcare systems and national economies through increased medical costs, reduced productivity and long term disease management.

As obesity rates continue to raise across many countries, experts project that its economic impact will become even greater in the coming decades. Data from the Global Obesity observatory shows that overweight and obesity continue to place a significant economic burden on countries worldwide.

The financial burden overweight and obesity can be measured as a share of the total Gross Domestic Product (GDP). In 2020, the economic impact varied from about 1% of GDP in many African countries to more than 3% in countries within the American region.

By 2026, these costs are expected to rise to over 2% of in Africa, more than 4% in the Americas, and more than 5% in middle East countries. Based on data collected in 161 countries, if current trends continue, the global economic burden of overweight and obesity is predicted to exceed 3% of GDP by 2060.

The sharpest increases are expected in lower- resource nations, where total costs may rise fourfold between 2019 and 2060 in high-income countries, and 12 – 25 times in low- and middle income countries.

Lowering projected obesity and overweight levels by 5% annually, or maintaining them at 2019 levels, could save approximately $430 billion or $2.2 trillion each year between 2020 and 2060 worldwide.

Social consequences of overweight and Obesity

Obesity have a significant social impact on individuals and communities worldwide. People living with obesity often experience discrimination in workplace, schools, and health care settings. Society frequently treats obesity as a personal weakness, which can contribute to depression, isolation and a poorer quality of life.

Although obesity was once viewed mainly as an issue in wealthy countries, it is now rising rapidly in low and middle- income nations, creating serious challenges for already overburdened healthcare systems. These social challenges may also influence educational opportunities, employment, and overall quality of life.

4. PREVENTING AND MANAGING OVERWEIGHT AND OBESITY

Overweight and obesity are major public health concerns that are largely preventable and manageable through healthy lifestyle choices, supportive environments, and effective public health interventions. They are complex conditions shaped by biological, behavioral, medical, asocial, environmental and economic influences rather than a single cause. 

Early Prevention

Prevention should begin early in life and continue throughout all stages of development. WHO recommends maintaining appropriate weight gain during pregnancy, encouraging exclusive breastfeeding during the first six months of life and continuing breastfeeding up to two years or beyond.

Children should be supported to develop health habits around nutrition, physical activity, sleep and reduced sedentary behavior, regardless of their current weight status.

Limiting screen time, reducing sugary drinks and energy –dense foods, and promoting balanced diets rich in fruits, vegetables, legumes, whole grains and nuts are important preventive strategies. Healthy lifestyle habits should also include regular physical activity, quality sleep, emotional wellbeing and avoiding tobacco and alcohol

Managing obesity

Health professionals play a key role in obesity prevention and management. Routine assessment of weight and height, counselling on healthy lifestyle, and guidance on treatment options are essential parts of care.

Depending on the individual’s needs, management may include nutrition advice, physical activity planning, therapeutic treatment, or surgical interventions where appropriate. Healthy People 2030

It is important to monitor related risk factors such as blood pressure, blood glucose, cholesterol levels and mental conditions. Obesity is not only a personal health issue but also a chronic condition that may require structured medical support, especially when it is severe or accompanied by other health problems. Pan American Health organization (PAHO)

Public health response

Effective prevention and management of obesity require more than individual effort alone. Supportive communities and policies are needed to make healthy foods and physical activities more accessible, affordable, and appealing.

Governments and health systems can strengthen obesity prevention by improving food environments, expanding health services and integrating obesity control into wider efforts to address non- communicable diseases. Action is also needed across sectors such as food production, marketing, urban planning, education, and poverty reduction.

The food industry has an important responsibility to reduce unhealthy ingredients in processed foods, make healthier options more available, limit the marketing of unhealthy foods to children and adolescents and support healthy eating and physical activity in workplaces.

Overweight and obesity are preventable and manageable, but the solution must be broad and coordinated. Lasting progress depends on healthy personal habits, supportive health services, and public policies that create environments where healthy choices are easier to make.

Addressing obesity effectively means working across individuals, families, communities, governments, and industries to improve health outcomes and quality of life.

FAQ

1.   1.Is obesity only caused by eating too much?

No, obesity is influenced by a combination of biological, behavioral, environmental, social and medical factors.

2.     2.Can children outgrow obesity?

Some children may improve with healthy changes, but childhood obesity often continues into adulthood if it is not addressed early.

3.     3.Is obesity a disease?

Yes, WHO classifies obesity as a chronic disease linked to abnormal fat accumulation that can harm health.

4.     4.What is the best way to prevent obesity?

The best approach is early prevention through healthy eating, regular physical activity, enough sleep, limited screen time, and supportive environment

5.     5. Can obesity be managed without surgery?

Yes, many people mange obesity through diet, physical activity, behavior change, and medical support when needed. Surgery is usually reserved for specific cases.