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Overweight and Obesity in Children and Adolescents

Overweight and Obesity in Children and Adolescents: Why?

Causes of Childhood Obesity

by Dr. Mandar V. Bichu
Published: Last Updated on 0 comment


Overweight and obesity in children and adolescents is increasing world-wide over the years. Such Overweight-Obesity affected children are prone to many serious physical and psychological diseases, and they are also candidates for adult obesity and even premature deaths. This article discusses the causes of Childhood Obesity.

Childhood Obesity: Key Stats by WHO

  • 39 million children under the age of 5 were overweight or obese in 2020.
  • Over 340 million children and adolescents aged 5-19 were overweight or obese in 2016.
  • Obesity has nearly tripled in the world since 1975.
  • From 4% in 1975, the prevalence of overweight and obesity increased to more than 18% in children and adolescents in 5-19 years age-group.

What are Overweight and Obesity? How do we diagnose them in children and adolescents?

Overweight and Obesity are conditions with abnormal excessive accumulation of fat in the body that may impair health.

BMI (Body Mass Index) is a simple inexpensive weight to height index, which is used to diagnose overweight and obesity in a population. Sex-specific BMI-for-Age charts are used to diagnose overweight and obesity in children and adolescents.

Sex-specific BMI-for-Age more than 85th percentile and less than 95th is Overweight, while above 95th percentile is Obesity.

Read Overweight, Obesity and BMI.

Why are our children and teenagers becoming overweight?

Overweight and Obesity in children and adolescent is sometimes related to heredity (genetics), sometimes to some medical disorders and sometimes, even to some medications. However, most of the cases in the ongoing pandemic of obesity are because of certain environmental and lifestyle factors. Let’s review all these causes one by one.

Heredity (Genes) causing Obesity

Heredity or inherited set of genes does make an individual more prone for obesity. There are 30% chances of obesity in a child if one parent is affected by obesity, and almost 90% chances if both parents are. Multiple genes determining appetite, food intake, hormones, fat cell differentiation, and glucose and fat metabolism have been studied by scientists in this respect.

However, the research concludes that the genetic predisposition alone doesn’t lead to obesity. Personal behaviour and environment play important roles in how these genes would express themselves. Healthy diet and lifestyle changes can prevent obesity in such genetically prone children.

Diseases causing Obesity

Genetically transmitted diseases such as Prader-Willi syndrome and Bardet-Biedl syndrome; Hormonal disorders such as Cushing’s Disease, hypothyroidism, and Poly-Cystic Ovarian Disease (PCOD), and Psychological problems such as depression and various eating disorders, can sometimes cause associated obesity. (Here, it is interesting to note that many times these psychological problems may not be the causes, but rather the effects of obesity!)

However, the number of such disease-related obesity cases in overall population’s overweight-obesity spectrum is limited.

Medicines (Drugs) causing Obesity

Medicines given for various illnesses can sometimes cause obesity through various mechanisms such as appetite stimulation, changing or slowing metabolism, water retention or making the person feel tired for physical activity.

Some such examples are

  • Medicines for diabetes, such as insulin, thiazolidinediones, and sulfonylureas
  • Antipsychotic medicines such as haloperidol, clozapine, risperidone, olanzapine, quetiapine, and lithium
  • Antidepressant medicines like amitriptyline, imipramine, paroxetine, escitalopram, citalopram, mirtazapine, and sertraline
  • Epilepsy medicines like valproate, divalproex, carbamazepine, and gabapentin
  • Steroid hormone medicines like prednisone or birth control pills
  • Blood pressure-reducing medicines like beta-blockers such as propranolol and metoprolol

The ongoing explosion of overweight-obesity across the age-groups has little to do with the medicines’ effects or side-effects.

According to WHO,
“ The fundamental cause of obesity and overweight is an energy imbalance between calories consumed and calories expended.”

WHO Article on Overweight and Obesity.

Environmental & Lifestyle Factors causing Obesity

There are multiple environmental and lifestyle factors, which contribute to this Energy Imbalance through increased calories consumed, and decreased calories expended or spent. These are the main causes behind the global epidemic of Overweight and Obesity.

Here are few of them.

Sedentary Screen Time with Fast Foods
A common picture in many urban homes

Changed Food Habits

With both working parents and busy lifestyles in many urban families, ‘home-cooked foods’ and ‘family meals together’ are going out of practice. This has increased reliance on packaged snacks, fast foods, or foods from outside restaurants. Such packaged/fast/outside foods are rich in salt, saturated fats, and sugar. These foods are calorie-dense nutrient-poor, meaning they are full of calories but low on healthy nutrients.

Increased consumption of sugary drinks such as sodas or fruit juices- (many times as a replacement for water or milk)- in many families is another reason of surplus empty calories adding on.

The portion sizes of food have increased significantly, both, at home and in restaurants. This also contributes to excess caloric consumption.

Sedentary life patterns

 Advances in transport, technology and food availability in modern urban lives have significantly reduced many common physical activities like walking, running, or climbing, and domestic chores like cooking or cleaning. Unavailability of safe, nearby outdoor play facilities in many places have meant children have been forced to spend most of the time indoors at home.

Learn about Keeping Your Children Active.

Increased Screen Time

Spending hours sitting in a chair, sofa, or bed, in front of screens of computers, mobile phones and televisions has become part and parcel of daily studies, work and entertainment. Since 2020, the Covid 19 pandemic has made this ‘screen-bound Indoor life’ even worse.

These screen-bound indoor moments are often associated with consumption of unhealthy packaged snacks, fast foods, and sugary drinks.

Read Managing Screen Time in Children.

Lack of sleep

Sedentary life and screen exposure often also cause lack of sleep, which in turn causes imbalance of hormones controlling hunger.

Lack of sleep causes increased level of Ghrelin (Hormone increasing hunger) and decreased level of Leptin (Hormone controlling hunger). Thus, a sleep-deprived person feels hungrier and eats more.

Family factors

Family practices play major roles in shaping up of an individual’s lifestyle. Unhealthy food and physical activity habits of parents or elder family members are likely to be followed as role models by children.

Parenting practices such as avoidance of breastfeeding, prolonged bottle-feeding and force feeding can also contribute to the overweight and obesity in children.

Social factors

Targeted advertising of fast foods and sugary drinks is a major factor making these bad health trends ‘Cool’ in the minds of children and adolescents.

The excess salt, sugar and fats used in packaged and fast foods by Food Industry, for enhancing taste and shelf life, is another contributory factor.

Food Inequity: The healthy foods like fresh fruits-vegetables-meats are much costlier than unhealthy packaged or fast foods. Studies have found that the town parts where underprivileged communities are staying are often having more fast-food outlets and less of healthy food outlets. Thus, the underprivileged communities to find it hard to buy healthy foods, first for their cost, and secondly for their not easy availability in the vicinity.


  • The problem of Overweight and Obesity in Children and Adolescents is increasing over the decades.
  • BMI-for-Age charts are used to diagnose Overweight and Obesity in children and adolescents.
  • Heredity, Diseases and Drugs play some role in Obesity.
  • Fundamental cause for Obesity is Energy imbalance because of caloric intake being in excess of caloric expenditure.
  • Environmental factors and lifestyle factors are mainly behind the explosion of obesity across age-groups and across the globe.
  • They include packaged snacks, fast-foods, sugary drinks, increased portion sizes, sedentary life patterns, excess screen exposure, lack of sleep, avoidance of breastfeeding, prolonged bottle-feeding, targeted advertising of fast foods and sugary drinks, excess salt-sugar-fat use by packaged and fast food industries, and social inequity about healthy food availability.

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