Obesity is a condition where a person has accumulated abnormal or excessive body fat that causes negative effects on health. For an individual, obesity is usually the result of an imbalance between calories consumed and calories expanded. An increased consumption of high calorie foods, without an equal increase in physical activity leads to an increase in weight. Decreased levels of physical activity will also result in an energy imbalance and lead to weight gain.
Once it was thought as a problem of high income countries now the problem of overweight and obesity are increasing in low income and middle income countries especially in urban areas. Since 1980 obesity has doubled worldwide. In 2014 more than 1.9 billion adults (18 years and older) and 41 million children under the age of five were overweight. Nearly half of the children under five who were overweight or obese in 2014 lived in Asia.
Overweight and obesity are emerging health problems in India. According to National family health survey India-3 (NFHS-3), thirteen percent of women (15-49 Years) and nine percent of men (15-49 Years) were overweight or obese in 2005-06. Overweight prevalence was higher in urban areas than rural areas and lower in people who are involved in agriculture or manual work.
World Health Organization (WHO) defines overweight and obesity as abnormal or excessive fat accumulation that presents a risk to health. A simple measure commonly used to classify overweight and obesity in adults is body mass index (BMI). BMI is defined as a person's weight in kilograms divided by the square of his height in meters (kg/m2). WHO identifies overweight when BMI is greater than or equal to 25; and obesity when BMI is greater or equal to 30. In Asians, the cut-offs for overweight (≥23.0kg/m2) and obesity (≥25.0kg/m2) are lower than WHO criteria due to risk factors and morbidities.
Overweight and obesity kills more people than underweight and act as a predisposing factor for non-communicable diseases such as cardiovascular diseases (heart attack and stroke), diabetes, musculoskeletal disorders (osteoarthritis), some cancers (including breast, ovarian, prostate, liver, gallbladder, kidney, and colon).
Obesity during childhood also causes breathing difficulties, increased risk of fractures, hypertension, and psychological effects. In later life with high chances of obesity, cardiovascular diseases, diabetes can lead to disability and premature death.
Overweight, obesity and their related non-communicable disease are preventable. By making the choice of healthier food and regular physical activity overweight and obesity can be prevented.
Last updated on February 2019
Weight gain usually occurs over time. Most people know when they've gained weight. Some of the signs of overweight or obesity include:
- Clothes feeling tight and needing a larger size.
- Weight gain as compared to previous measurement
- Having extra fat around the waist.
- A higher than normal body mass index (a person's weight in kilograms divided by the square of his height in meters (kg/m2)) and waist circumference.
Other symptom may be:
- Increased sweating
- Back and joint pains
- Feeling tired even with routine activities
- Inability to cope with sudden physical activity
- Psychological problems such as low self –esteem, low confidence level
- Without proper treatment obesity can lead to various health problems as dyslipidaemia, hypertension, type 2 diabetes, coronary heart disease, stroke, osteoarthritis, cancer, infertility, sleep apnea.
Obesity doesn't occur overnight. It develops gradually over time when there is disturbance in energy balance. Energy balance means that “energy in” through food intake and “energy out” through physical activities. Consuming excess calories from high-fat foods, sugars and doing little or no daily physical activity over the long time will lead to weight gain. The reasons for the imbalance between calorie intake and energy out may vary from individual to individual.
Genetics may play a role in conversion of food into energy and how body burns calories during exercise. Genes may affect the amount of fat storage and distribution of fat in body.
Family history- A person is more likely to develop obesity if one or both parents are obese. Overweight and obesity tend to run in families not just because of genetics but family members tend to share similar eating and activity habits. Children’s choices, diet and physical activity habits are influenced by their surrounding environment.
Unhealthy diet- Diet rich in calories (fast foods), high calorie beverages, oversized portions, bad eating habits (eating between meals, preference to sweets, refined foods, and fats), diet lacking with fruits and vegetables; all these factors contribute to weight gain.
Sedentary life style- With a sedentary lifestyle such as sedentary occupation and inactive recreation (watching television) more calories are stored in the body every day than used through exercise. Thus sedentary lifestyle promotes weight gain. If there is any associated medical problems such as arthritis can lead to decreased activity; that contributes to weight gain.
Health conditions- Some medical conditions may cause over weight and obesity because of hormonal disturbances such as hypothyroidism, Cushing’s syndrome and poly cystic ovarian syndrome (PCOS).
- In hypothyroidism there is lack of thyroid hormone that slows down the metabolism and causes weight gain.
- PCOS is a condition that affects women of child bearing age. It is often associated with obesity due to high levels of androgens.
- In Cushing syndrome there is increased production of cortisol hormone from adrenal glands.
Medicines-Certain medicines such as corticosteroids, antidepressants and medicines used for seizure control may cause weight gain.
Emotional factors- For some people, eating habits are influenced by emotions such as sadness, stress, boredom or anger and they react by eating excessively.
Smoking- Quitting smoking is often associated with weight gain. However, smoking is a serious health risk, and quitting is more important than possible weight gain.
Age- Obesity can occur at any age, even in young children. Infants with excessive weight have increased chances of obesity in later life. As age increases, muscle mass tends to decrease and some hormonal changes also occur; these factors along with less active lifestyle increase the risk of obesity in later age.
Sex- Men have more muscle mass and use more calories (even at rest) than women. Thus, women are more likely to gain weight as compare to men with the same calorie intake; however midlife weight gain in women is mainly due to aging and lifestyle, but at menopause hormonal changes also play a role in weight gain.
Pregnancy- Woman gain weight during pregnancy and, some women find it difficult to lose weight after child birth. This weight gain may contribute to the development of obesity in women.
Lack of sleep- Not having enough sleep or getting too much sleep can cause changes in hormones that may increase appetite and craving for foods high in calories and carbohydrates, which can contribute to weight gain.
Environment- If environment doesn’t support healthy lifestyle, it encourages obesity. Some reasons include-
- Lack of neighborhood sidewalks, parks, and safe places for recreation prevents people to be physically active.
- People working with long work hours and time spent commuting don’t have enough time to be physically active.
- Lack of access to healthy foods such as fresh fruits and vegetables, or, for some people these healthy foods are too costly.
- Lack of awareness about healthy diet and healthy cooking practices.
- Food advertisements for high-calorie, high-fat snacks and sugary drinks promote people to buy them.
There are two different kinds of distribution of body fat that play a role in determining risk of obesity –related health problems;
- excess body fat distributed around the waist (apple-shaped figure, intra-abdominal fat);
- excess body fat distributed on the hips and thighs (pear-shaped figure, fat under the skin)
Fat collected around the waist (apple-shaped figure) carries more risk for obesity related health problems.
(a) Assessment of obesity
Height and weight are the most simple and commonly used measures. Overweight and obesity can be diagnosed by calculating body mass index (BMI) of an individual. BMI generally correlates with fat accumulation although it can sometimes misclassify total body fat content as seen in athletes who are muscular, have high BMI due to muscle weighing more than fat and will have BMI within the overweight range even though they are not fat. The adult BMI cut-offs are not considered appropriate for children as they are still growing.
BMI is defined as a person's weight in kilograms divided by the square of his height in meters (kg/m2). BMI (Metric Formula) =Weight in Kilograms/Height in meters2 .
WHO defines overweight when BMI is greater than or equal to 25.0kg/m2; and obesity when BMI is greater or equal to 30.0kg/m2. In Asians, the cut-offs for overweight (≥23.0kg/m2) and obesity (≥25.0kg/m2) is lower than WHO criteria due to risk factors and morbidities.
Waist circumference: It is measured at the midpoint between the lower border of the rib cage and the iliac crest. Waist circumference ≥102 cm in men and ≥88cm in females is associated with an increased risk of metabolic complications.
Waist: Hip ratio (WHR): High WHR (>1.0 in men and >0.85 in women) indicates abdominal fat accumulation.
(b) Obese persons should have a full medical assessment including routine evaluation of co-morbidity such as diabetes, hypertension, dyslipidaemia. A cardiovascular examination is needed for those older than 40 years or persons having history of heart disease.
(c) Various laboratory tests may be performed to assess co- morbid conditions-
- Fasting lipid profile
- Liver function tests
- Thyroid function tests
- Fasting glucose and haemoglobin A1c(HBA1c)
Parks Text book of Preventive and Social Medicine, 22nd Edition, Page No.369-371
For most people who are overweight or obese, the safest and most effective way to lose weight is setting goals with life style changes such as eating fewer calories and being physically active. If lifestyle changes are not enough then only medicines and weight loss surgery are options. While suffering from any co-morbid condition such as diabetes, high blood pressure, cardiovascular disease, osteoarthritis consult your physician prior to starting life style changes.
Set realistic goals:
- The best way to lose weight is decrease it slowly. A weight loss of 1 to 2 pounds a week is safe and will give the time to adopt new healthy life style changes. Hence 5-10 percent of current body weight can be loosed over six months time.
- If a child in the family is overweight or obese the focus should be to encourage him for healthy eating habits and physical activity and if any health condition related to overweight or obesity is present, pediatrician should be consulted.
(a) Life style changes:
Life style changes include healthy eating habits and physical activity.
(i) Healthy eating habits provide body the sufficient nutrients for maintaining good health, but not so many that it causes weight gain. Healthy diet includes:
- Limit energy intake from total fats and shift fat consumption away from saturated fats to unsaturated fats and towards the elimination of trans-fatty acids. This can be achieved by-
- eating fat-free and low-fat dairy products, such as low-fat yogurt, cheese, and milk
- avoiding whole milk, whole-milk cheese, cream, butter, and ice cream
- avoiding foods containing solid fats(vanaspati ghee, lard, coconut, and palm oils) such as deep fried fast foods
- Limiting foods prepared with partially hydrogenated oils (Doughnuts, cookies, crackers, muffins, pies and cakes)
- Limiting use of ground beef, sausage, and processed meats
- consume whole-grain foods (whole-wheat bread and chapati, oatmeal, and brown rice), legumes and nuts
- increase consumption of fruits and vegetables
- limit the intake of free sugars
- limit salt (sodium) consumption from all sources and ensure that salt is iodized.
Portion size: Cutting back on portion size is a good way to eat fewer calories. Avoid oversized portions. Use a smaller plate, bowl, and glass.
Food weight: Eat foods that are lower in calories and fat for a given amount of food; for example; replacing a full-fat food product that weighs two ounces with a low-fat product that weighs the same. Another helpful practice is to eat foods that contain a lot of water, such as vegetables, fruits, and soups.
Very-low-calorie diet (VLCD): gives less than 800 calories a day. Though these diets can lead to rapid weight loss, but they aren't a safe method for everyone. VLCDs are only recommended when obesity-related complication would need rapid weight loss.
(ii) Physical activity- This is an important part of weight reducing programme. Regular physical exercise is essential to increase energy expenditure. Few important suggestions are-
- Consult the physician before starting physical activity specially those who are having other medical problems along with obesity.
- Start physical activity slowly and increase intensity and duration gradually with time. Low to medium intensity is sufficient. It is not necessary to participate in strenuous activity.
- Choose activities that you enjoy and that fit into your daily life.
- Start activity with doing more everyday activities, such as taking the stairs instead of elevators and doing house hold chores.
- The next step is to start walking, biking, or swimming at a slow pace and increase the exercise time, or increase the intensity level of the activity gradually. (Brisk walk, dancing, gardening, and water aerobics are moderate-intensity physical activity).
(iii) Behavioral changes- Changing behaviors or habits related to food and physical activity is important for losing weight such as:
- Change the habits promoting weight gain such as watching television for long hours.
- Keep a record of your weight loss.
- Ask for help or encouragement from friends, family, and health care provider.
- Reward the success for meeting weight-loss goals.
(b)Prescription anti-obesity drugs can be useful adjuncts to diet and exercise for obese adults who have failed to achieve weight loss with diet and exercise. Drugs are only prescribed when BMI is 28 kg/m 2 or more with other weight related conditions or BMI 30 kg/m 2 or more.
(c)Weight loss surgery-also called bariatric surgery, is sometimes used to treat people who are severely obese (for BMI of 35 kg/m 2 with co-morbidity or BMI over 40 kg/m 2). Common weight-loss surgeries include:
- Gastric bypass surgery
- Laparoscopic adjustable gastric banding (LAGB)
- Biliopancreatic diversion with duodenal switch
- Gastric sleeve
(d)Vagal nerve blockade is another treatment for obesity. It involves implanting a device under the skin of the abdomen that sends intermittent electrical pulses to the abdominal vagus nerve, which tells the brain when the stomach feels empty or full. This new technology is used in adults who have not been able to lose weight with a weight-loss programme and who have a BMI of 35 - 45 kg/m 2 with at least one obesity-related condition, such as type 2 diabetes.
Obesity can increase the risk of developing many health conditions -
- Type 2 Diabetes
- Hypertension (High blood pressure)
- Coronary heart disease and stroke
- Metabolic syndrome (a combination of diabetes, high blood pressure and obesity)
- Cancer- Colon cancer, breast cancer in postmenopausal women, endometrial cancer
- Gallstones (stones in gallbladder)
- Gastro-oesophageal reflux disease(GORD)- (condition in which acids from stomach regurgitates in to oesophagus)
- Osteoarthritis- Pain and stiffness in joints
- Low back pain
- Reduced fertility
- Sleep apnoea (interrupted breathing during sleep)
- Liver disease
- Kidney disease
- Pregnancy complications such a gestational diabetes, Pre-eclampsia, foetal defects
- Obesity reduces life expectancy by an average of 3 to 10 years according to its severity.
This is observed that increase in the prevalence of obesity is largely due to the obesogenic environment rather than medical and genetic problems in the individuals. Therefore prevention of overweight and obesity should aim creating environments that encourage behaviuoral changes in terms of diet and physical activity.
These efforts must not only focus on the prevention of obesity in those who have not yet become obese (primary prevention), but also on prevention of further weight gain and promotion of weight loss in those who are already obese before they develop the complications of obesity (secondary prevention).
Breastfeeding has been suggested as a potential protective factor against weight gain in childhood and this is important because overweight children and adolescents are at risk of becoming overweight adults.
At individual level, people can follow:
Eating a healthy diet can help in preventing obesity-
- Limit total fat intake and shift fat consumption away from saturated fats to unsaturated fats and elimination of trans fats.
- Increase consumption of fruits, vegetables, pulses, whole grains, legumes and nuts
- Limit intake of sugar and salt
Regular physical activity helps maintain a healthy weight-
People should engage in adequate levels of physical activity (60 minutes a day for children and 150 minutes spread through the week for adults). At least 30 minutes of regular, moderate-intensity physical activity on most days reduces the risk of obesity and co-morbidities.
WHO has recommended that food industry can play a significant role in promoting healthy diets by:
- reducing the fat, sugar and salt content of processed foods;
- ensuring that healthy and nutritious choices are available and affordable to all consumers;
- restricting marketing of foods high in sugars, salt and fats, especially those foods aimed at children and teenagers; and
- ensuring the availability of healthy food choices and supporting regular physical activity practice in the workplace.