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INTRODUCTION Obesity is a
disorder of body weight regulatory systems characterized by an accumulation of excess body fat.
Obesity is defined as a process where fat accumulates over a long period of time due to an increased rate of storage of triglycerides in adipose tissue.
INTRODUCTION In primitive society – less favor in
storage of excess calories as fatHigh level of physical activityFood was only available intermittently
The people today:Sedentary lifestyle – obesity epidemicAbundance and wide variety of palatable,
inexpensive foods
As adiposity has increased – increased the risk associated diseases:Arthritis, diabetes, hypertension,
cardiovascular disease and cancer
Obesity is a risk factor for non-insulin-dependent diabetes mellitus, atherosclerosis and hypertension.
Android type obesity is a greater risk factor for these diseases, rather than the gynoid type obesity.
The question of why obesity is a risk factor for these diseases remains mystery, but probably due to:OvereatingEating too much high-fat food & too few
high-carbohydrate foodsSedentary habitsGenetics
TYPES OF FAT
WHITE FAT VS. BROWN FAT Adipose tissue (fat) consists of a mass
of adipocyte cells (fat cells)Loosely held by the collagen fibers
Two forms of adipocyte tissue:White fatBrown fat
WHITE FAT VS. BROWN FAT White fat:
White or yellow colorHas relatively few nerves and blood
vesselsEach cell contains a single large droplets of
TGRole: As a site of energy storage for
physical activity
WHITE FAT VS. BROWN FAT Brown fat:
Contains more nerves and blood vesselsEach cell contains several small droplets
of TG, and large numbers of mitochondria
Role: only for heat productionOccurs in all newborns mammalsAbsent in adult humans, but presence in
adult hibernating animalsDoes not respond much to low- or
overeatingMitochondria – not for ATP production,
but instead to produce heat.
SUBCUTANEOUS FAT VS. VISCERAL FAT
In the body, fat can be deposited as either subcutaneous fat or visceral fat
Subcutaneous fatOccurs as a continuous layer throughout
the body (under the skin)Can be measured using skinfold
techniqueDistribution is not similar in male and
femaleFemale has thicker subcutaneous fat at
certain area (e.g. buttock)
SUBCUTANEOUS FAT VS. VISCERAL FAT
Visceral fatDeep fatFat that is located within the abdomen
In between organsDistribution is similar in male and female
ANDROID FAT VS. GYNOID FAT
Two types of fat distribution in the body:Android fatGynoid fat
Can be measured using waist-to-hip ratio
ANDROID FAT VS. GYNOID FAT Android fat
Male-type, central typeOccurs in the abdomen
Excess abdominal and upper body fatAs men become obese, they tend to
accumulate fat in the android pattern.Occurs above the waistline In women, waistline is often absent.
ANDROID FAT VS. GYNOID FAT Gynoid fat
Female-type, peripheral typeLower body fat
Excess accumulation of fats around the hips and thighs, as well as on the arms
Occurs below the waistline
HYPERTROPHIC VS. HYPERPLASTIC OBESITY Hypertrophic obesity
Development of obesity, in which the size of individual adipocytes cell increases
Hyperplastic obesityDevelopment of obesity, in which the number of adipocytes cells increase
HYPERTROPHIC VS. HYPERPLASTIC OBESITY As triacylglycerols are stored, adipocytes
can expand to an average of 2-3 times their normal volume.However, the ability of fat cell to expand is
limited.
Prolonged overnutrition cause stimulation of pre-adipocytes within the adipose tissuepre-adipocytes will proliferate and
differentiate into mature fat cells, thus increase the number of adipocytes.
HYPERTROPHIC VS. HYPERPLASTIC OBESITY Most obesity is due to combination of
hypertrophy (increase in size) and hyperplasia (increase in number)
Obese individuals can have up to 5 times the normal number of fat cells
HYPERTROPHIC VS. HYPERPLASTIC OBESITY If excess calories cannot be
accommodated within adipose tissue, excess fatty acids spill over into other tissues (e.g: muscle and liver).
This is called as ectopic fat. Ectopic fat is associated with insulin resistance condition.
Weight loss
Weight gain
Pre-adipocytes
Weight gain
Weight gain
Weight gain
Weight loss
SIGNALING PATHWAY FOR REGULATING ADIPOCYTE
FORMATIONSee drawings
TECHNIQUES FOR MEASURING BODY
COMPOSITION
HEIGHT AND WEIGHT Using a ruler and scale. Example: Seca body meter, Tanita
weighing scale
WAIST-TO-HIP RATIO Measurement using measuring
tape Circumference of
waist/circumference of hip Widely used to assess male- and
female-type of obesity Waist/hip ratio that is associated
with high risk of obesity and diabetesMale: ≥ 1.0Female: ≥ 0.8
SKINFOLD MEASUREMENT Skinfold thickness is measured by
pinching the skin Using calipers Measure layers of skin and
subcutaneous fat This method can be used to measure
total body fat
DENSITOMETRY Measurement of body composition Principle: Displacement of air/water as
assumption to body density Air densitometer – example: Bod Pod Water densitometer
BIOELECTRICAL IMPEDANCE Involves connecting electrodes to the
hand and feetPassing a mild electric current
throughout the body Give and indication of total body fat
OTHER TECHNIQUES Body mass index (BMI) Ultrasound Computed tomography Example: CT scan, DEXA
.:: THANK YOU ::.
