Obesity – Risk Factors, Complications And Associated Diseases
Obesity is a disease characterized by weight gain due to adipose tissue and is defined by a value of body mass index (BMI) > 30 kg/m².
In clinical practice, assessing the weight status is made by weighing the patient and calculating the body mass index:
- BMI = W / H² (W = weight, H = height).
According to BMI values, the World Health Organization classifies weight status as:
- Underweight: BMI < 18.5 kg/m²;
- Normal weight: BMI = 18.5 kg/m² – 24.9 kg/m² ;
- Overweight: BMI = 25kg/m² – 29.9 kg/m²;
- Obese: BMI > 30 kg/m².
Because BMI does not give indications on the distribution of adipose tissue in the body, the latter is assessed by measurement of some anthropometric parameters:
- Abdominal circumference, it is correlated with abdominal fat mass. As waist circumference is greater, the higher the risk of cardiovascular morbidity and mortality is. Values of abdominal circumference greater than 94 cm in men and 80 cm in women, is the criterion required for defining the metabolic syndrome;
- Waist-hip index represents the ratio of abdominal girth and pelvic girth;
- Abdominal index represents the ratio of waist circumference and height (normal = 0.5).
The weight of a subject is related to the ideal weight and can be calculated by the Broca’s formula:
- Ideal weight = Height (cm) – 100 (in men);
- Ideal weight = Height (cm) – 105 (in women).
Obesity Risk Factors
Etiopathogenesis of obesity is not fully elucidated, but is believed to be multifactorial, the risk factors involved are:
- genetic factor: studies on twins, adopted children and the familial studies support the role of genetic factors in the pathogenesis of obesity;
- Age: although obesity may occur at any age, the risk increases with age;
- Sex: women generally have a higher BMI then men;
- Physiological circumstances: pregnancy, puberty, menopause, andropause;
- Socio-economic conditions: obesity affects mostly the social groups with low economic possibilities and low cultural level;
- Sedentary life;
- Psychological factors: depression, psychological traumas;
- Disturbance of eating behavior: hypercaloric diet, some jobs (chefs, confectioners). Food preferences, in particular, hiperlipidic food, have little effect on satiety, which favors the installation of obesity. Increased consumption of sweets promotes weight gain both by caloric intake, and by hyperinsulinemia and hypoglycemia, responsible for the increase of food intake. Rare and high-calorie meals can lead to the development of obesity;
- Certain medicines: in the presence of genetic predisposition, antipsychotics (chlorpromazine, haloperidol), antidepressants (doxepin, lithium salts), antiepileptics (carbamazepine), beta blockers, corticosteroids, isoniazid, insulin, sulfonylureas, may encourage the development of obesity.
Obesity consists in the increase of total mass of adipose tissue, caused by hyperplasia or hypertrophy of adipocytes, which are overloaded with triglycerides.Normal adult body works after the first principle of thermodynamics, according to which energy intake is equal to energy of consumption. Increased energy intake and decreased energy consumption will lead to a surplus energy which will be stored in the body as fat.
In subjects prone to obesity and obese:
- Adipocytes: these cells in obesity, have an increased volume and a greater number, have a higher turn-over of triglycerides and secrete an increased amount of leptin, resistin, proinflammatory cytokines, plasminogen activator inhibitor, angitensinogen. These substanete, in high concentrations increase the atherogenic and diabetogenic risk. Simultaneously, in the obese people is reduced secretion of adiponectin, a substance with a protective role against atherogenesis and type 2 diabetes mellitus;
- Insulin: in general in obese, there is an increase insulin secretion, which stimulates hepatic synthesis of triglycerides and decreased HDL-cholesterol production;
- Liver and skeletal muscle: in basal conditions, in people with obesity, the takeover of fatty acids by the liver and skeletal muscle is higher than in people with normal weight.
In men with normal weight, body fat is 12% -20% of body weight, while in women is between 20% and 30%.
From the morphological point of view, obesity has two types:
- Hyperplasic obesity, characterized by an increased number of fat cells, which are maintaining their normal diameter. Clinic, this type of obesity has an early onset, before 18 years or before 20 years, and is usually gynoid and resistant to treatment;
- Hypertrophic obesity, characterized by hypertrophy of adipocytes, in the sense that the number of adipocytes is smaller, but fat cell diameter is larger than normal. Disposition is predominantly android, often begins in adulthood and is associated with diabetes mellitus, hyperlipidemia, hypertension and coronary artery disease.
- Mixed obesity, combines the characters of the two types of obesity above.
- Primary obesity: which includes most of the cases, it is a category that remains after the exclusion of secondary obesity and particular obesity;
- Secondary obesity: endocrine (hypothyroidism, Cushing’s syndrome, male hypogonadism, polycystic ovary syndrome in women, growth hormone deficiency), tumors or other lesions involving the hypothalamic areas of appetite control.
- Android obesity, characterized by waist-hip index > 0.85 in women and > 0.95 in men and the abdominal index > 0.5. Adipose tissue accumulation occurs predominantly in the upper half of the body. These patients have hyperinsulinemia, diabetes mellitus, dyslipidemia, hyperuricemia, coronary artery disease, hypertension. This type of obesity is hypertrophic, and the treatment offers slightly better results;
- Gynoid obesity, characterized by waist-hip index <0.85 in women and <0.95 in men and the abdominal index <0.5. Adipose tissue accumulation occurs predominantly in the lower half of the body (pelvis, thigh). It is associated with varicose veins and arthritis. This type of obesity is hyperplasic and resistant to treatment.
According to BMI, obesity has three grades:
- Grade I: BMI = 30 kg / m² – 34.9 kg / m²;
- Grade II: BMI = 35 kg / m² – 39.9 kg / m²;
- Grade III: BMI > 40 kg / m².
Obesity evolutive criteria:
- Dynamic obesity, represents the growth phase, weight gain phase or accumulation phase;
- Static obesity, when the maximum weight is reached.
Obesity Complications And Associated Diseases
Among pathological states associated with obesity, some may be considered complications and other related diseases.
Obesity, particularly the android is associated with increased cardiovascular risk, due to atherosclerosis. This risk grows with the increasing of BMI and waist circumference.
- Hypertension, the disease often associated with obesity, increases the cardiovascular risk. Weight loss will reduce blood pressure, independent of other factors;
- Atherosclerosis, the most severe manifestation beeing the coronary manifestation (coronary artery disease) and the cerebral manifestation (cerebral vascular accident or stroke);
- Heart failure, due to coronary disease. This pathology associated,aggravates the significance of obesity.
Obesity metabolic complications:
Obesity, in particular the abdominal one is associated with insulin resistance and hyperinsulinemia.
- Diabetes mellitus type 2: association of type 2 diabetes and obesity is known, because of insulin resistance and hyperinsulinemia. 80% of patients with type 2 diabetes are overweight or obese;
- Dyslipidemia: obesity is associated with a series of plasma lipid abnormalities, including hypertriglyceridemia, low HDL-cholesterol levels and increased LDL-cholesterol and VLDL-coloesterol levels, which have atherogenic potential;
- Metabolic syndrome.
- Hiatal hernia;
- Gallstones, 50% – 70% of patients with gallstones are obese;
- Acute pancreatitis
- Non-alcoholic fatty liver.
- Mixed ventilatory dysfunction, predominantly restrictive, evolving to respiratory failure;
- Pickwick syndrome, characterized by extreme obesity, intense daytime somnolence, hypoxemia, hypercapnia, cyanosis, and right ventricular dilatation with the picture of decompensated chronic cor pulmonale;
- Sleep apnea, manifested by periods of apnea more than 10 seconds during sleep, often associated with cardiac arrhythmias.
- Arthrosis in the major joints of the lower limbs and spine.
Venous circulatory disorders:
- Varicose veins, two thirds of people with varicose veins are obese;
- Chronic venous failure;
- Deep venous thrombosis.
- Endometrial and breast cancer are twice as common in obese women than normal-weight women;
- Esophageal cancer;
- Colo-rectal cancer.
- Behavioral disorders;
- Bacterial infections;
- Fungal infections.
Obesity Evolution And Prognosis
Obesity has a progressive evolution (dynamic phase), as long as there is a surplus of energy. At one point, the patient is no longer gaining weight (static phase), because in most cases, when maximum weight is achieved, the appetite is reduced. Regression to the ideal weight is possible especially in patients with android, moderate overweight. This is achieved by changing eating habits, exercise and if is necessary medical treatment and surgery. Obesity is a disease with poor prognosis, associated morbidity and mortality are correlated with the level of weight excess.