By Dr. S.P. Pradhan on 8th May, 2023
Obesity is a part of the metabolic syndromes like diabetes, hypercholesterolemia. It is a bigger burden now than the infectious diseases.
Obesity overview
The incidence of overweight and obesity is rapidly increasing as a comorbid factor in lifestyle diseases. By an estimate global obesity may reach about 18% in men and 21% in women by 2025.
The etiological factors of obesity involve interplay of genetic, physiological, environmental factors. Overweight and obesity are interrelated to body mass index. Normal range of body mass index(BMI) is 18-24.99. Overweight is BMI between 25-29.99. BMI more than 30 is obese.
The etiological and risk factors for Obesity
Genetics
Some obesity related genes run in families causing their children obese. Many genes can be involved in its linkage with obesity. But particularly the MC4R gene or the melanocortin 4 receptor gene mostly linked to the obesity.
In most obese people no single genetic etiology can be identified. It is most often an interplay of genetic and environmental factors.
Brain responds to the food intake by getting the signals from the receptors from the adipose tissue, pancreas and digestive tract.
It is regulated by hormones like leptin, insulin and ghrelin respectively. The change in genetic responses modify the responses and govern obesity tendency.
Familial factor
Overweight and obesity may be a familial problem due to genetics or familial inactivity of food habits.•
Food habits- The trans fats are big risk factors for hypercholesterolemia. The processed foods, packaged foods, high calorie beverages, chocolates, chips contribute to high cholesterol and obesity.•
Sedentary lifestyle- Physical inactivity also another etiological factor. Physical inactivity decreases the metabolism and incidences of obesity increase.
Medical conditions – Cushing syndrome, Prader-Willi syndrome are associated with obesity.
Gut microbiome – Microbial flora has also a link to the obesity. They play a symbiotic role in the host. Actively involved in metabolism and regulate the fatty tissue composition. The physiological process like digestion is affected by our gut microbiota. Obesity related disorders are associated with specific alterations in composition and function of human microbiota. Research are on for targeting our gut microbiota to alter the metabolism by supplements in form of probiotics, prebiotics or both.
Complications due to Obesity
Diabetes
Obesity is associated with insulin resistance and type 2 diabetes. Obesity is the primary cause of metabolic syndrome associated with diabetes and hypercholesterolemia. Hypercholesterolemia further complicates the diabetes leading to complications such as heart attack and stroke. Obesity is the most vital modifiable risk factor of diabetes and treatment of diabetes is confined on reduction of body weight.
Recent data shows lifestyle intervention on patients with impaired glucose tolerance results in prevention of development to overt diabetes. The most important recommendation for obese patients with type 2 diabetes is to have a moderately hypocaloric diet with reduced intake of saturated fat with increased physical activity(Hans Hauner et al).
Potential risk factors in the pathogenesis of diabetes in obese patients are increased free fatty acids level, increased cytokines, increased leptin levels(A D Mooradian et al). Epidemiological studies suggest modest loss of body weight significantly affects the amelioration of insulin resistance and therapeutic goal of controlling dual problem of diabetes with obesity.
Coronary heart disease
Obesity leads to hypercholesterolemia, which causes partial blockage of coronary vessels supplying heart. Hypercholesterolemia leads to formation of plaques of fatty acids in the lumen of blood vessels supplying heart. It gradually narrows the lumen of major vessels. This compromises the blood flow to a major organ like heart causing ischemia. Ischemia further compromises the situation resulting in structural loss of cardiac tissue. These series of events ultimately cause heart attack and heart failure.
Now a days obesity is prevalent in all ages. Due to this the incidence of young age heart attack is on the rising trend. Young age heart attack means those get heart attack in their fourth decade of life. The increase in incidence of heart attack is attributed to faulty food habits, lack of exercise and stress.
Foods lacking green vegetables and fruits but significant trans fats aggravates the obesity and coronary diseases linkage. Trans fats are abundant in fast foods, deep fried foods, chocolates, ultra processed foods. These trans fats gradually accumulate in the major vessels leading to thrombosis, ultimately heart attack.
Cancer
The cause of many cancers like breast, ovary, endometrium, prostate, liver, gall bladder, pancreas, thyroid, oesophagus have their root in obesity as a risk factor. This may be attributed to the level of inflammation, increased level of insulin, insulin like growth factor, sex hormones. Obesity may be responsible for around 20% of cancers overall.
There is growing evidence of physical activity and breast, colon cancers(Kathleen Y Wolin et al). The overall mortality is increased in overweight and obese patients(Eugenia E Calle et al). Increased BMI(Body mass index) has a higher prevalence of common and less common cancers(Andrew G Renehan et al).
The obesity related cancers can be diagnosed by proper screening.
• Screening for inflammatory diseases like Chrohn’s disease, ulcerative colitis
• Family history of cancers
• Breast self palpation
• Unusual menstrual bleeding
• Non-healing oral ulcers
• Abnormal pap smear in case of cytological examination in women
Stroke
It can lead to stroke due to cerebral vessel thromboembolism.
Obstructive sleep apnoea
Growth of soft tissues in floor of mouth may obstruct the upper respiratory passage causing respiratory distress requiring life threatening ventilatory support. In obstructive sleep apnea syndrome, the patient experience episodes of apnea and hypopnea episodes due to partial or complete closure of the upper airway. It decreases the ventilatory drive and leads to the respiratory failure. Episodes of apnea can decrease the oxyhemoglobin level drastically depending on the period of apnea.
Leptin hormone is involved in feeding and metabolism. Its level are increased in obstructive sleep apnea syndrome. Some studies show that it is directly associated with the severity of the syndrome.
Link between obstructive sleep apnea and diabetes
Obstructive sleep apnea results in intermittent hypoxia. Frequent desaturation reduces the glucose drived insulin secretion. Many clinical studies have proven increased association between patients with obstructive sleep apnea and diabetes.
In pediatrics population also the link between intermittent hypoxia with glucose induced insulin secretion is studied and clinical studies have shown a link between obesity related obstructive sleep apnea and prediabetes and diabetes.
Arthritis aggravation
Obesity may aggravate the joint disorders like arthritis as it puts pressure on the weight bearing joints. Degeneration of cartilage is further aggravated by metabolic syndromes induced free radical damage.
Gynaecological problems like Poly cystic ovarian disease is also aggravated by obesity.
Edmonton Obesity Staging System(EOSS) tool
Stage 0
- No obesity related risk factors identified
- No intervention required
Stage 1
- Subclinical risk factors
- Mild physical symptoms or mild impairment of well being
Stage 2
- In this stage established symptoms along with comorbidities are seen.
- Moderate obesity related symptoms and moderate impairment of well being.
Stage 3
- Heresignificant obesity related end organ damage occurs with significant functional limitations and ability.
Stage 4
- Severe end organ damage resulting organ failure and severe functional disability.
WHO response
Adopted in WHO health assembly in 2004 and a political declaration in 2011 on non communicable diseases(NCD) the “WHO Global strategy on Diet, Physical activity and Health” describes action needed to support healthy diet and regular physical activity. The strategy calls upon all stakeholders to take action at central, regional and local level to support the campaigning on healthy diet and regular exercise.
How to prevent Obesity?
1. Avoid trans fats and junk foods
Fatty foods with increased trans fats like deep fried foods, pizza, burgers, chowmin, chocolates, cheese , oils like mustard oil have increased trans fats. They not only increases the chances of obesity but also raise the incidence of of high cholesterol and diabetes.
2. Regular exercise
Regular physical activity keep the lean muscle mass and BMI in check and fight obesity. At least we must devote twenty minutes for aerobic exercises to keep away from metabolic syndromes.
3. Avoid smoking and alcohol
4. Regular health check ups like measurement of blood pressure, blood sugar, total cholesterol level to avoid unforeseen complications.
