Obesity And Overweight: Definition, Causes, and Treatment

What is obesity?

Obesity and overweight are defined as unusual and excessive accumulation of fat which may be harmful to one’s health. Taking into consideration body weight for a given height, obesity or overweight describes a weight that is greater than what is regarded as a healthy weight.

Body Mass Index (BMI) is a simple screening tool for obesity or overweight. BMI is calculated using a person’s weight in kilograms divided by the square of the height in meters (kg/m2). BMI gives an estimate of body fat but does not directly measure body fat. Thus, people who build muscles may have a BMI that may be suggestive of being overweight even though they may not have excess body fat.

BMI for adults

Calculate your BMI using Adult BMI calculator 

According to the Centre for Disease Control and Prevention, CDC, 

BMI less than 18.5 is underweight

BMI 18.5 to < 25, is normal weight 

BMI 25.0 to < 30, is overweight

BMI 30 or high is obesity

Subclassification of obesity is indicated below 

Class 1: BMI of 30 to < 35

Class 2: BMI of 35 to < 40

Class 3: BMI of 40 or higher – this category may sometimes be referred to as “severe” or “extreme” obesity

BMI for children and teenagers

For these age groups, BMI is specific for age and sex. A child’s weight status is calculated using a percentile which is age- and biological sex-specific.

The body composition for children varies as they age and it is different for both boys and girls. It is needful to express levels of BMI among children and teens relative to that of other children of the same age and biological sex.

In respect of the weight status category and the corresponding percentile ranges, 

Underweight children are within the < 5th percentile range

Normal or healthy weight within the 5th percentile to < 85th percentile range

Overweight children within the 85th percentile to < 95th percentile range

Obese children: 95th percentile or greater.

Calculate your BMI if you fall with this range using this BMI calculator.

Waist circumference and Obesity

Ethnic groupMenWomen
Caucasian ≥94 cm [≥37 in.] ≥80 cm [≥31.5 in.]
South Asian, Chinese, Japanese≥90 cm [≥35.4 in.]≥80 cm [≥31.5 in.]

Waist circumference is a better predictor of cardiometabolic risk than BMI.

However, reproducibility is a concern. Caucasian cutoff points can be used for South and Central American, sub-Saharan African, Eastern Mediterranean, and Middle Eastern populations until more specific data are available.

What are the causes of obesity and overweight?

Obesity can result from a combination of factors or may result from such individual factors such as lifestyle, genetics, behavioral, hormonal and metabolic influences.

However, the underlying cause of obesity and overweight is an imbalance between the calories you take in and the calories you burn through routine daily activities and exercise.

What are the risk factors for being obesed or overweight?


Genetics may play a role in food metabolism, regulating appetite and how the body burns calories during exercise. Some gene variants may increase hunger and food intake thus contributing to obesity.

Family history may indicate the effects of shared genetics and environment among close relatives.


Unhealthy diet. Diets that are energy dense, lacking in fruits and vegetables, ladened with high fat and sugars when taken in outsized portions contribute to weight gain.

Physical inactivity. An increase in physical inactivity patterns due to lifestyle requiring sitting or little activity, can lead to weight gain because you can easily consume more calories often than you burn through exercise.

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Certain disease and medications:

In some people, obesity can be linked to a medical cause. Diseases such as Polycystic Ovarian Syndrome, hypothyroidism, Cushing syndrome and other conditions. Arthritis can also lead to reduced activity, which may result in weight gain.

Some medications result in weight gain if you don’t counterbalance their effects through healthy diet or physical activity. These medications include some antidepressants, anti-seizure and antipsychotic medications, birth-control pills, diabetes medication, steroids and so on. 

Environmental, social and economic issues

Environmental and societal changes linked to development may contribute to weight gain as these indirectly influence changes in dietary patterns and physical activity. Not being able to access healthy foods, limited safe areas for exercise as a result of poor settlement and inadequate public education on healthy living can result in weight gain. 


Obesity can occur at any age. However, hormonal changes and a decreased active lifestyle associated with aging increases the risk of obesity. Besides, there is a decrease in the rate of metabolism as one ages, making weight gain easy.


Weight gain is common during pregnancy, and some women may find it difficult to lose this weight gained which may contribute to the development of obesity. 

Insufficient or excess sleep

Getting little or too much sleep can lead to hormonal changes that increase your appetite and hunger and craving for foods that are high in calories, which can contribute to weight gain.

Psychological and other factors

External factors that affect well-being and mood causing depression can sometimes lead to weight gain. Some people may seek high-calorie food for emotional comfort in stressful situations.

Quitting smoking is good, but quitting is sometimes associated with weight gain which may lead to obesity. Often, this occurs as people resort to more food during smoking withdrawal. Quitting is of great importance to healthy living and thus, it is important to concentrate on diet and exercise while quitting, at least after the initial withdrawal period.

What are the health consequences of overweight and obesity?

Elevated BMI is a major risk factor for chronic diseases such as:

Cardiovascular diseases: 

Obese individuals have a potential of high blood pressure, dyslipidemia (increased cholesterol, increased low density lipoproteins and decreased high density lipoproteins), coronary artery disease, heart failure, atrial fibrillation and stroke

Type 2 Diabetes: 

Obesity affects the body’s use of insulin in regulating blood sugar levels. Insulin resistance is increased in obese patients and this increases the risk for diabetes

Musculoskeletal Disorders

This occurs especially in osteoarthritis – a highly disabling disease where the joints degenerate. Obesity places stress on the weight-bearing joints, besides contributing to the progress of inflammation

Certain Cancers

Obesity is linked to the increased risk of developing some cancers. Tissues, organs and systems affected include breast, genitourinary (endometrial, ovarian), gastrointestinal (oesophagus, colorectal, liver, gallbladder, pancreas, stomach), kidney, non-Hodgkin’s lymphoma and multiple myeloma.

Digestive disorders

Obese persons are more likely to have heart burns and disorders of the liver (steatohepatitis and cirrhosis) and gallbladder (cholelithiasis)

Reproductive Health Problems:

Obesity may cause impotence in men and irregular menses, anovulatory cycles and infertility in women. 

Sleep disorders

Obesed individuals have increased risk of sleep apnea, a serious sleep disorder where there is a transient cessation of respiration during sleep. There is also obesity-associated hypoventilation syndrome where there is decreased strength and endurance of respiratory muscles, decreased ventilatory drive as well as closure of small airways.

Severe COVID-19 symptoms. 

Obesity has been widely reported to be linked to the disease progression of coronavirus disease 2019 (COVID-19) 

Psychosocial problems

This study shows a strong link between obesity and depression.

Childhood overweight and obesity is linked to an increased probability of obesity, early death and physical impairment in adulthood. Besides increased risks in the future, obesity in children can cause difficulty in breathing, increased chances of fractures, hypertension, early indicators of cardiovascular disease, resistance to insulin activity and psychological effects.

How is obesity diagnosed?

In addition to BMI and waist circumference measures, your doctor may request for other tests and workups for obesity related health risk assessments. These include:

Basic Labs – Complete blood count and differential, lipid profile, electrolytes, serum creatinine, Aspartate aminotransferase AST, Alanine aminotransferase ALT, fasting glucose and/or HbA1C, Thyroid test

Cardiac Workup – Stress test if indicated

Sleep Apnea Workup —Sleep study if clinical suspicion for obstructive sleep apnea

Obesity Hypoventilation Workup – Bicarbonate >27 mEq/L is a reasonable screening test. Arterial Blood Gas (ABG) to confirm hypercarbia (elevated carbon dioxide levels in blood). 

How is obesity managed?

People who are obese and have not been able to lose weight on their own can seek available medical help. 

Team work including a dietician, physiotherapist and other health care workers may be essential in weight loss programs.

Consult dietitian for dietary/behavior modification. Consult a psychologist if psychological issues (depression, abuse, binge eating, emotional eating) are major barriers to weight loss success.

On certain occasions, medications or surgery for weight loss may be recommended by the doctor. 

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Which lifestyle changes can help reduce weight or control obesity?

Obesity and other chronic medical conditions are mostly preventable.

The healthcare team can guide obese individuals on choice of food and developing a healthy eating plan suitable for the individual. 

Individuals can reduce total caloric content from fat and sugars. This can be done by consuming more fruits and vegetables, soluble fibres found in oats, beans and nuts as well as engaging in regular simple exercise. The WHO recommends 60 minutes a day for children and 150 minutes per week for adults – at least 30 minutes of moderate intensity physical activity for at least 3 days a week. Advice on exercise should have considerations to the age and presence of other medical conditions.

Reduced calorie diet (estimated energy requirement with 500 kcal/day deficit would lead to weight loss of 0.5 kg/week for first 3 months. A reduction of 5–10% of initial body weight is the minimal initial goal, as this correlates with improvement in comorbidities (≥10% usually required for clinically important improvements).

Failing that, weight maintenance (no change from baseline weight) is the goal. Exercise (at least 150 min of moderate intensity physical activity/ week).

At the community level, a supportive environment and counseling can shape the choice of people, such as those involved in selecting healthy foods and needed routine exercise. Support groups may also help identify such conditions as depression and eating disorders which may contribute to weight gain

Which medications are prescribed for weight loss?

Patients with BMI >30 kg/m2 or BMI >27 kg/m2 if comorbid conditions exist may be considered for medications in addition to lifestyle and behavioral changes

The aim is to reduce >5% of initial body weight in 3–6 months. 

The following medications are approved by the Food and Drug Administration (FDA), USA for long-term use (at least 12 weeks)

Orlistat, a pancreatic lipase inhibitor reduces fat absorption. This is not approved for use in children less than 12 years. 

Phentermine/topiramate enhance satiety and suppresses appetite.

Bupropion/naltrexone also enhances satiety as well as work by other mechanisms.

If drug therapy is successful, indefinite use of it may be considered. The doctor will monitor use of medication slowly. Contact your pharmacist for further information on the drug concerning administration and side effects.

What are some of the surgeries for weight loss?

Bariatric surgery is the common term used to refer to weight loss surgeries. This type of surgery works by reducing the quantity of food one can consume safely and/or limiting food absorption in the intestines. 

Surgery is considered for patients with BMI ≥40 kg/m2 or BMI ≥35 kg/m2 if comorbid conditions exist.

Patients require lifelong post-operative follow-up. Surgery is the only treatment demonstrated to reduce mortality 

Gastric restriction procedures (gastric banding [adjustable band squeezes and restricts upper gastric area] is safest but requires close follow-up and long-term outcomes inferior to other procedures; sleeve gastrectomy [resection of greater curvature gaining popularity]). 

Malabsorptive/ diversionary procedures decrease absorption via bypass of parts of small intestine and also result in a variable amount of restriction of gastric size (Roux-en-Y gastric bypass, biliopancreatic diversion)


  1. Centre for Disease Control and Prevention (CDC), October 2020. Overweight and obesity 

https://www.cdc.gov/obesity/index.html [Accessed on January 17, 2021]

  1. World Health Organization (WHO), April 2020. Obesity and overweight

https://www.who.int/news-room/fact-sheets/detail/obesity-and-overweight [Accessed on January 17, 2021]

  1. Chu Y, Ynag J, Shi J, Zheng P, Wang C (2020). Obesity is associated with increased severity of disease in COVID-19 Pneumonia: A systematic review and meta-analysis. Eur J Med Res 2020; 25:64 
  2. Eckel R H (2008). Nonsurgical management of obesity in adults. N Engl J Med 2008; 358: 1941-50
  3. Heymsfied B S, Wadden T A (2017). Mechanism, Pathophysiology and Management of Obesity. N Engl J Med 2017; 376:254-66


Dr. Solomon Kwesi Otchere (Pharmacist)

Dr. Solomon Kwesi Otchere is a Pharmacist by profession in Ghana. He is passionate about informed healthy lifestyle and diet options necessary for preventing many disease conditions. He also empowers patients and clients to make savvy choices on medications needful to promote good health.

Chief Editor at Wapomu.com

MPSGH, MRPharmS, MPhil.

Isaiah Amoo is a practicing community pharmacist in good standing with the Pharmacy Council of Ghana who has meaningful experience in academia and industrial pharmacy. He is a member of the Royal Pharmaceutical Society, England, UK and currently pursuing his overseas pharmacy assessment programme (MSc) at Aston University, UK. He had his MPhil degree in Pharmaceutical Chemistry at Kwame Nkrumah University of Science and Technology. He has about 5 years’ experience as a community Pharmacist and has also taught in academic institutions like KNUST, Kumasi Technical University, Royal Ann College of Health, and G-Health Consult. He likes to spend time reading medical research articles and loves sharing his knowledge with others.

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