Obesity (BMI >30) has exceeded the WHO definition of epidemic ( >15% world wide)

Prevalence of BMI  <18.5 and > 40 is about 1-2% in the general population

In most countries, the prevalence of overweight is about 2-3 times as great as the prevalence of obesity.

Obesity is usually more common in those with low socio economic status. ( but in India china etc where the incidence of obesity is less, it is the affluent people who are affected )

A 40 year old man with a BMI >30 can expect to lose 7 years of his life compared to a normal weight individual

Myth: OBESITY is due to low BMR.  Obese individuals have a higher resting BMR!! A low BMR is normalised by about 5-10 kg weight gain. Thus while up to 10 kg weight gain is probably explainable by a low BMR, further increases are unlikely unless excessive food intake or low physical activity contributes.   Int J Obes. 1985;9 Suppl 2:1-7.  Note that a low BMR would result in a low energy intake, unless eating is taken up for the pleasure of it!

The proportion of fat as percentage of body weight may increase by more than 2 fold between 25 and 75 years of age, despite BMI remaining steady.

Obese individuals use a greater amount of energy than lean individuals in walking the same distance, contributing to the greater energy expenditure seen in the obese

In UK men, the risk of CHD increases by 10% for every 1 kg/m2 increase in BMI above 22.

For every 10% increase in weight there is a BP increase of 6 mm Hg systolic and 4 mm Hg diastolic.

One third of obese people have hypertension.

Hypertension in obese is due to sodium retention due to RAA axis changes, sympathetic activation, and insulin resistance.

Increased sympathetic activity in the obese results in increased urinary nor adrenaline excretion

In men and women with a waist circumference of more than 102 cm or 88 cm respectively, the risk of CHD is similar to that at BMI >30 kg/m2

In practice, some degree of Obstructive Sleep Apnoea (OSA) occurs in all men with a neck circumference of >42 cm.

People tend to walk 25 miles less a week than a man in 1950

There is a direct relationship between BMI and LV mass ( as an adaptation to meet the high metabolic demands of the greater body mass)

Higher BMI is accompanied by expansion of total circulating volume with consequent increase in the preload and LV end diastolic volume
 

Satiation is the suppression of hunger by a meal, and this determines meal size. Satiation is followed by a variable duration characterised by absence of hunger and is referred to as satiety. Satiation and satiety have separate mechanisms.

Visceral fat is more dangerous than subcutaneous fat due to:

1. venous effluent delivering higher NEFA levels to the liver
2. less responsiveness to insulin effect
3. higher response to catecholamine stimulated lipolysis
4. less leptin secretion
5. higher PAI-1 secretion

It has been suggested that the optimal BMI in the older adult might be in the range of 27-30. Thus being overweight  may not confer any extra mortality risk in the older individual.  Arch Intern Med. 2001 May 14;161(9):1194-203   But this may not hold true for type 2 diabetics.  Diabet Med. 1990 Mar-Apr;7(3):228-33.  Interestingly, recent reports seem to suggest that intentional weight loss in older overweight and obese  men might result in reduction in hip bone density. J Clin Endocrinol Metab. 2005 Apr;90(4):1998-2004
 

DRUGS CAUSING OBESITY

Antiepileptics: gabapentin, sod valproate, phenytoin  Drugs Today (Barc). 2005 Aug;41(8):547-55.
Anti depressants: mirtazipine, citalopram, lithium, Timely Top Med Cardiovasc Dis. 2005 Oct 28;9:E31.
Anti psychotics: chlorpromazine, risperidone, Olanzapine  Diabetologia. 2005 Feb;48(2):215-21
Sulphonylureas, insulin
Anti-HIV drugs: indinavir, ritonavir
Pizotifen
Steroids
Progesterone, Estrogens
Atenolol
Cyproheptadine  Appetite. 1986;7 Suppl:85-97

further reading:         Obes Rev. 2004 Aug;5(3):167-70.
                                        J Clin Psychiatry. 2004 Feb;65(2):267-72.

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    This page was last updated on: 07/03/2007

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