Definition and Measurement
Obesity Is A State Of Excess Adipose Tissue Mass. Although Often Viewed As Equivalent To Increased Body Weight, This Need Not Be The Case, ¾Lean But Very Muscular Individuals May Be Overweight By Arbitrary Standards Without Having Increased Adiposity. Body Weights Are Distributed Continuously In Populations, So That A Medically Meaningful Distinction Between Lean And Obese Is Somewhat Arbitrary. Obesity Is Therefore More Effectively Defined By Assessing Its Linkage To Morbidity Or Mortality.
Although Not A Direct Measure Of Adiposity, The Most Widely Used Method To Gauge Obesity Is The Body Mass Index (BMI), Which Is Equal To Weight/Height2 (In Kg/M2). Other Approaches To Quantifying Obesity Include Anthropometry (Skin-Fold Thickness), Densitometry (Underwater Weighing), Computed Tomography (CT) Or Magnetic Resonance Imaging (MRI), And Electrical Impedance. Based On Unequivocal Data Of Substantial Morbidity, A BMI Of 30 Is Most Commonly Used As A Threshold For Obesity In Both Men And Women. Large-Scale Epidemiologic Studies Suggest That All-Cause, Metabolic, And Cardiovascular Morbidity Begin To Rise When Bmis Are 25, Suggesting That The Cut-Off For Obesity Should Be Lowered. A BMI Between 25 And 30 Should Be Viewed As Medically Significant And Worthy Of Therapeutic Intervention, Especially In The Presence Of Risk Factors That Are Influenced By Adiposity, Such As Hypertension And Glucose Intolerance.
The Distribution Of Adipose Tissue In Different Anatomic Depots Also Has Substantial Implications For Morbidity. Specifically, Intraabdominal And Abdominal Subcutaneous Fat Have More Significance Than Subcutaneous Fat Present In The Buttocks And Lower Extremities. This Distinction Is Most Easily Made By Determining The Waist-To-Hip Ratio, With A Ratio >0.9 In Women And >1.0 In Men Being Abnormal. Many Of The Most Important Complications Of Obesity, Such As Insulin Resistance, Diabetes, Hypertension, And Hyperlipidemia, And Hyperandrogenism In Women, Are Linked More Strongly To Intraabdominal And/Or Upper Body Fat Than To Overall Adiposity. The Mechanism Underlying This Association Is Unknown But May Relate To The Fact That Intraabdominal Adipocytes Are More Lipolytically Active Than Those From Other Depots. Release Of Free Fatty Acids Into The Portal Circulation Has Adverse Metabolic Actions, Especially On The Liver.
Physiologic Regulation of Energy Balance
Substantial Evidence Suggests That Body Weight Is Regulated By Both Endocrine And Neural Components That Ultimately Influence The Effector Arms Of Energy Intake And Expenditure. This Complex Regulatory System Is Necessary Because Even Small Imbalances Between Energy Intake And Expenditure Will Ultimately Have Large Effects On Body Weight. Alterations In Stable Weight By Forced Overfeeding Or Food Deprivation Induce Physiologic Changes That Resist These Perturbations: With Weight Loss, Appetite Increases And Energy Expenditure Falls; With Overfeeding, Appetite Falls And Energy Expenditure Increases. This Latter Compensatory Mechanism Frequently Fails, However, Permitting Obesity To Develop When Food Is Abundant And Physical Activity Is Limited. A Major Regulator Of These Adaptative Responses Is The Adipocyte-Derived Hormone Leptin, Which Acts Through Brain Circuits (Predominantly In The Hypothalamus) To Influence Appetite, Energy Expenditure, And Neuroendocrine Function.
Energy Expenditure Includes The Following Components:
(1) Resting Or Basal Metabolic Rate;
(2) The Energy Cost Of Metabolizing And Storing Food;
(3) The Thermic Effect Of Exercise; And
(4) Adaptive Thermogenesis, Which Varies In Response To Chronic Caloric Intake (Rising With Increased Intake). Basal Metabolic Rate Accounts For About 70% Of Daily Energy Expenditure, Whereas Active Physical Activity Contributes 5 To 10%. Thus, A Significant Component Of Daily Energy Consumption Is Fixed.
The Adipocyte and Adipose Tissue
Adipose Tissue Is Composed Of The Lipid-Storing Adipose Cell And A Stromal/Vascular Compartment In Which Preadipocytes Reside. Adipose Mass Increases By Enlargement Of Adipose Cells Through Lipid Deposition, As Well As By An Increase In The Number Of Adipocytes. The Process By Which Adipose Cells Are Derived From A Mesenchymal Preadipocyte Involves An Orchestrated Series Of Differentiation Steps Mediated By A Cascade Of Specific Transcription Factors.
Although The Adipocyte Has Generally Been Regarded As A Storage Depot For Fat, It Is Also An Endocrine Cell That Releases Numerous Molecules In A Regulated Fashion. These Include The Energy Balance-Regulating Hormone Leptin, Cytokines Such As Tumor Necrosis Factor (TNF) A, Complement Factors Such As Factor D, Prothrombotic Agents Such As Plasminogen Activator Inhibitor I, And A Component Of The Blood Pressure Regulating System, Angiotensinogen. These Factors, And Others Not Yet Identified, Play A Role In The Physiology Of Lipid Homeostasis, Insulin Sensitivity, Blood Pressure Control, And Coagulation And Are Likely To Contribute To Obesity-Related Pathologies.
Etiology of Obesity
Though the molecular pathways regulating energy balance are beginning to be illuminated, the causes of obesity remain elusive. In part, this reflects the fact that obesity is a heterogeneous group of disorders. At one level, the pathophysiology of obesity seems simple: a chronic excess of nutrient intake relative to the level of energy expenditure. However, due to the complexity of the neuroendocrine and metabolic systems that regulate energy intake, storage, and expenditure, it has been difficult to quantitate all the relevant parameters (e.g., food intake and energy expenditure) over time in human subjects.
Role of Genes vs. Environment Obesity is commonly seen in families. Inheritance is usually not Mendelian, however, and it is difficult to distinguish the role of genes and environmental factors. Adoptees usually resemble their biologic rather than adoptive parents with respect to obesity, providing strong support for genetic influences. Likewise, identical twins have very similar BMIs whether reared together or apart, and their BMIs are much more strongly correlated than those of dizygotic twins. These genetic effects appear to relate to both energy intake and expenditure.
Whatever the role of genes, it is clear that the environment plays a key role in obesity, as evidenced by the fact that famine prevents obesity in even the most obesity-prone individual. In industrial societies, obesity is more common among poor women, whereas in underdeveloped countries, wealthier women are more often obese. In children, obesity correlates to some degree with time spent watching television. High-fat diets may promote obesity, as may diets rich in simple (as opposed to complex) carbohydrates.
Specific Genetic Syndromes
A number of complex human syndromes with defined inheritance are associated with obesity. Although specific genes are undefined at present, their identification will likely enhance our understanding of more common forms of human obesity. In the Prader-Willi syndrome, obesity coexists with short stature, mental retardation, hypogonadotropic hypogonadism, hypotonia, small hands and feet, fish-shaped mouth, and hyperphagia. Laurence-Moon-Biedl syndrome involves obesity, mental retardation, retinitis pigmentosa, polydactyly, and hypogonadotropic hypogonadism.
Other Specific Syndromes Associated with Obesity
Cushing’s Syndrome Although obese patients commonly have central obesity, hypertension, and glucose intolerance, they lack other specific stigmata of Cushing’s syndrome. Nonetheless, a potential diagnosis of Cushing’s syndrome is often entertained. Cortisol production and urinary metabolites (17OH steroids) may be increased in simple obesity.
Hypothyroidism The possibility of hypothyroidism should be considered when evaluating obesity, but it is an uncommon cause of obesity; hypothyroidism is easily ruled out by measuring thyroid stimulating hormone (TSH). Much of the weight gain that occurs in hypothyroidism is due to myxedema.
Insulinoma Patients with insulinoma often gain weight as a result of overeating to avoid hypoglycemia symptoms. The increased substrate plus high insulin levels promotes energy storage in fat. This can be marked in some individuals but is modest in most.
Craniopharyngioma and Other Disorders Involving the Hypothalamus Whether through tumors, trauma, or inflammation, hypothalamic dysfunction of systems controlling satiety, hunger, and energy expenditure can cause varying degrees of obesity. It is uncommon to identify a discrete anatomic basis for these disorders.
Pathogenesis of Common Obesity:
Obesity can result from increased energy intake, decreased energy expenditure, or a combination of the two. Thus, identifying the etiology of obesity should involve measurements of both parameters. However, it is nearly impossible to perform direct and accurate measurements of energy intake in free-living individuals. Obese people, in particular, appear to underreport intake. Measurements of chronic energy expenditure have only recently become available using doubly-labeled water or metabolic chamber/rooms. In subjects at stable weight and body composition, energy intake equals expenditure. Consequently, these techniques allow determination of energy intake in free-living individuals. The level of energy expenditure differs in established obesity, during periods of weight gain or loss, and in the pre- or postobese state. Studies that fail to take note of this phenomenon are not easily interpreted.
There is increased interest in the concept of a body weight “set point.” This idea is supported by physiologic mechanisms centered around a sensing system in adipose tissue that reflects fat stores, and a receptor, or “adipostat,” that is in the hypothalamic centers. When fat stores are depleted, the adipostat signal is low, and the hypothalamus responds by stimulating hunger and decreasing energy expenditure to conserve energy. Conversely, when fat stores are abundant, the signal is increased, and the hypothalamus responds by decreasing hunger and increasing energy expenditure.
Pathologic Consequences of Obesity
Obesity has major adverse effects on health. Morbidly obese individuals (>200% ideal body weight) have as much as a twelvefold increase in mortality. Morality rates rise as obesity increases, particularly when obesity is associated with increased intraabdominal fat. It is also apparent that the degree to which obesity affects particular organ systems is influenced by susceptibility genes that vary in the population.
Insulin Resistance and Type 2 Diabetes Mellitus Hyperinsulinemia and insulin resistance are pervasive features of obesity, increasing with weight gain and diminishing with weight loss. Insulin resistance is more strongly linked to intraabdominal fat than to fat in other depots. The molecular link between obesity and insulin resistance has been sought for many years, with the major factors under investigation being: (1) insulin itself, by inducing receptor downregulation; (2) free fatty acids, known to be increased and capable of impairing insulin action; and (3) the cytokine TNF-a, which is produced by adipocytes, overexpressed in obese adipocytes, and capable of inhibiting insulin action. Despite insulin resistance, most obese individuals do not develop diabetes, suggesting that the onset of diabetes requires an interaction between obesity-induced insulin resistance and other factors that predispose to diabetes, such as impaired insulin secretion. Obesity, however, is a major risk factor for diabetes, and as many as 80% of patients with type 2 diabetes mellitus are obese. Weight loss, even of modest degree, is associated with increased insulin sensitivity and often improves glucose control in diabetes.
Reproductive Disorders Disorders that affect the reproductive axis are associated with obesity in both men and women. Male hypogonadism is associated with increased adipose tissue, often distributed in a pattern more typical of females. In men >160% ideal body weight, plasma testosterone and sex hormone-binding globulin (SHBG) are often reduced, and estrogen levels (derived from conversion of adrenal androgens in adipose tissue) are increased. Gynecomastia may be seen. However, masculinization, libido, potency, and spermatogenesis are preserved in most of these individuals. Free testosterone may be decreased in morbidly obese men whose weight exceeds 200% ideal body weight.
The waist/hip ratio may be the best predictor of these risks. When the additional effects of hypertension and glucose intolerance associated with obesity are included, the adverse impact of obesity is even more evident. The effect of obesity on cardiovascular mortality in women may be seen at BMIs as low as 25. Obesity, especially abdominal obesity, is associated with an atherogenic lipid profile, with increased low-density lipoprotein (LDL) cholesterol, very low density lipoprotein and triglyceride, and decreased high-density lipoprotein cholesterol. Obesity is also associated with hypertension. Measurement of blood pressure in the obese requires use of a larger cuff size to avoid artifactual increases. Obesity-induced hypertension is associated with increased peripheral resistance and cardiac output, increased sympathetic nervous system tone, increased salt sensitivity, and insulin-mediated salt retention; it is often responsive to modest weight loss.
Obesity may be associated with a number of pulmonary abnormalities. These include reduced chest wall compliance, increased work of breathing, increased minute ventilation due to increased metabolic rate, and decreased total lung capacity and functional residual capacity. Severe obesity may be associated with obstructive sleep apnea and the “obesity hypoventilation syndrome”. Sleep apnea can be obstructive (most common), central, or mixed. Weight loss (10 to 20 kg) can bring substantial improvement, as can major weight loss following gastric bypass or restrictive surgery. Continuous positive airway pressure has been used with some success.
Obesity is associated with enhanced biliary secretion of cholesterol, supersaturation of bile, and a higher incidence of gallstones, particularly cholesterol gallstones. A person 50% above ideal body weight has about a sixfold increased incidence of symptomatic gallstones. Paradoxically, fasting increases supersaturation of bile by decreasing the phospholipid component. Fasting-induced cholecystitis is a complication of extreme diets.
Obesity in males is associated with higher mortality from cancer of the colon, rectum, and prostate; obesity in females is associated with higher mortality from cancer of the gallbladder, bile ducts, breasts, endometrium, cervix, and ovaries. Some of the latter may be due to increased rates of conversion of androstenedione to estrone in adipose tissue of obese individuals.
Bone, Joint, and Cutaneous Disease:
Obesity is associated with an increased risk of osteoarthritis, no doubt partly due to the trauma of added weight bearing. The prevalence of gout may also be increased. Among the skin problems associated with obesity is acanthosis nigricans, manifested by darkening and thickening of the skin folds on the neck, elbows, and dorsal interphalangeal spaces. Acanthosis reflects the severity of underlying insulin resistance and diminishes with weight loss. Friability of skin may be increased, especially in skin folds, enhancing the risk of fungal and yeast infections. Finally, venous stasis is increased in the obese
1. Agaricus Muscarius
2. Ambra grisea
3. Ammonium carbonicum
4. Ammonium muriaticum
5. Antimonium crudum
7. Aurum Metallicum
8. Baryta Carbonica
9. Borax veneta
10. Bryonia alba
11. Calcarea ostrearum
13. Cantharis vesicator
15. China Officinalis
16. Cocculus Indicus
17. Conium maculatum
18. Euphorbium officinarum
21. Guaiacum officinale
23. Kali Bichromicum
24. Kali Carbonicum
26. Lac vaccinum defloratum
28. Lycopodium clavatum
29. Magnesia Carbonica
31. Muriaticum Acidum
32. Natrum Carbonicum
33. Nux Moschata
37. Pulsatilla nigricans
40. Senecio Aureus
41. Sepia officinalis
42. Spongia Tosta
44. Thuja occidentalis
45. Veratrum Album
Leucophlegmatic, blond hair, light complexion, blue eyes, fair skin; tendency to obesity in youth.
Psoric constitutions; pale, weak, timid, easily tired when walking. Disposed to grow fat, corpulent, unwieldy. Children with red face, flabby muscles, who sweat easily and take cold readily in consequence. Head sweats profusely while sleeping, wetting pillow far around. Profuse perspiration, mostly on back of head and neck, or chest and upper part of body.
During either sickness or convalescence, great longing for eggs; craves indigestible things, aversion to meat.
Girls who are fleshy, plethoric, and grow too rapidly.
Coldness: general; of single parts; head, stomach, abdomen, feet and legs; aversion to cold open air, “goes right through her”; sensitive to cold, damp air; great liability to take cold.
Feels better in every way when constipated.
Cold air; wet weather; cold water; from washing; morning; during full moon.
Dry weather, lying on painful side.
Persons with light hair, blue eyes, nervous but stout and plethoric habit.
Phlegmatic diathesis; lack of reactive force, especially with fat people, easily exhausted;
Indolent, dreads any kind of exercise; persons inclined to be jovial, yet get angry at trifles.
Children; dread open air; always chilly; refractory, clumsy, fat dirty, and disinclined to work or think.
Desires to be let alone; wants to lie down and sleep.
Homesickness [of the indolent, melancholic], with red cheeks and sleeplessness.
BETTER; while eating, from heat.
WORSE; open air, uncovering, draughts.
Suited to women, inclined to obesity, who suffer from habitual constipation; with a history of delayed menstruation.
“Excessive cautiousness; timid, hesitates; unable to decide about anything.
Sad, despondent; music makes her weep; thinks of nothing but death.
Takes cold easily, sensitive to draught of air.
Suffering parts emaciate.
Hears better when in a noise; when riding in a carriage or car, when there is a rumbling sound.
Sensation of cobwebs on forehead, tries hard to brush it off.
Decided aversion to coition.
WORSE; warmth, at night, during and after menstruation.
BETTER; in the dark, from wrapping up.
Stout, fleshy women with various trouble in consequence of leading a sedentary life;
Haemorrhagic diathesis, fluid blood and degeneration of red blood-corpuscles; ulcerations tend to gangrene.
Children dislike washing
Loses breath when falling asleep, must awaken to get breath.
Ill-humor during wet, stormy weather.
Right sided affections.
Aggravation; Cold, wet weather ; wet poultices; from washing; during menses.
Amelioration; lying on abdomen, on painful side, in dry weather.
Especially adapted to those who are fat and sluggish; or body large and fat, but legs too thin.
It is especially adapted to fat and sluggish patients who have respiratory troubles.
All mucous secretions are increased and retained.
Its periods of aggravations are peculiarly divided as to the bodily region affected; thus the head and chest symptoms are worse mornings, the abdominal in the afternoon, the pains in the limbs, the skin and febrile symptoms, in the evenings.
Desire to cry, but cannot.
BETTER; open air.
WORSE; head and chest symptoms in the morning; abdominal symptoms in the afternoon.
For children and young people inclined to grow fat; for the extremes of life.
Sensitive to the cold < after taking cold.
Child is fretful, peevish, cannot bear to be touched or looked at; sulky, does not wish to speak or be spoken to; angry at every little attention.
Great sadness, with weeping. Loathing life. Anxious lachrymose mood, the slightest thing effects her; abject despair, suicide by drowning.
A thick milky-white coating on the tongue, which is the red strand of the remedy;
Longing for acids and pickles.
Disposition to abnormal growths of the skin; fingernails do not grow rapidly;
Cannot bear the heat of sun; worse from over-exertion in the sun.
When symptoms reappear they change locality or go from one side of the body to the other.
Aggravation; After eating; cold baths; acids or sour wine; after heat of sun or fire; extremes of cold, or heat.
Amelioration; in open air, during rest, after a warm bath.
Complaints in fat women around climacteric.
Slightest emotion causing palpitation.
Worse from slight exertion.
Flying or swimming sensation, as if feet did not touch the ground
Especially in diseases of women and children. Women inclined to be fleshy, with scanty and protracted menstruation.
Adapted to persons of indecisive, slow, phlegmatic temperament; sandy hair, blue eyes, pale face, easily moved to laughter or tears; Affectionate, mild, gentle, timid, yielding disposition the woman’s remedy.
Weeps easily: almost impossible to detail her ailments without weeping.
The first serious impairment of health is referred to puberic age, have “never been well since”.
Secretions from all mucous membranes are thick, bland and yellowish-green.
Symptoms ever changing; no two chills, no two stools no two attacks alike; very well one hour, very miserable the next; apparently contradictory.
Thirstlessness with nearly all complaints;
Great dryness of mouth in the morning, without Thirst.
Aggravation; In a warm close room; evening, at twilight; on beginning to move; lying on the left; or on the painless side; very rich fat, indigestible food; pressure on the well side if it be made toward the diseased side; warm applications; heat.
Amelioration; in open air, lying on painful side, cold air or cold room, eating & drinking cold drinks, cold applications.
Fat, light-haired persons who suffer from catarrhal syphilitic or psoric affections. Fat, chubby, short-necked children disposed to croup and croupy affections.
Affections of the mucous membranes – eyes, nose, mouth, throat, bronchi; gastro-intestinal and genito-urinary tracts – discharge of a tough, stringy mucus which adheres to the parts and can be drawn into long strings.
Complaints occurring in hot weather. Liability to take cold in open air.
Pains: in small spots, can be covered with point of finger; shift rapidly from one part to another; appear and disappear suddenly.
BETTER, from heat.
WORSE, beer, morning, hot weather, undressing.
For disease of old people, dropsy and paralysis; with dark hair, lax fibre, inclined to obesity.
Great aversion to being alone.
After loss of fluids or vitality, particularly in the anaemic.
Pains stitching, darting, worse during rest and lying on affected side.
Cannot bear to be touched; starts when touched ever so lightly, especially on the feet.
WORSE, after coition; in cold weather; from soup and coffee; in morning about three o’clock; lying on left and painful side.
BETTER, in warm weather, though moist; during day, while moving about.
Dr Ajith Kumar D.S MD(Hom)
Department of Physiology
Govt. Homeopathic Medical College. Calicut. Kerala