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The
fundamental cause of obesity is the increase in calorie consumption and
decrease in calorie expenditure. This is termed as energy imbalance. Energy
imbalance is caused due to a number of reasons. The medical term for a range of
causes in combination to cause obesity is termed as obesogenic environment.
Obesogenic environment again involves many factors and we are going to look
upon them in India in relation to obesity.
One such
factor is genetics and heredity. Thriftiness which involves the thrifty gene is seen in Asia and India. This causes
metabolic syndromes, obesity and even diabetes mellitus.
In a nation of
starvation this gene would have been very helpful as it helps to store up fat
in the body and utilize it during food scarcity. Thriftiness is a very important
factor during obesity research. The focus has shifted from the thrifty gene to
the thrifty phenomenon as there has been a connection of low birth rate and
obesity in later life. For a population surviving with not enough nutrition
this thrifty gene would have been beneficial as it would have helped store fat
for times of need; but as a country progressing towards urbanization and
industrialization, this has caused less opportunity for physical activity and
more choice as to what food can be consumed.
This leads to more energy
consumption; this energy is not utilized and therefore stored by the adipose
tissue and further what adds fuel to the fire is the thrifty gene. There are
also other genetic factors which lead to obesity, although genetic deficiencies
are rare, they do exist and are one of the causes of obesity.
Genetic
Variations controlling appetite and metabolism affect the person’s dietary
pattern. Also Leptin Deficiency and Leptin Receptor Deficiency are a few of the
many other deficiencies which lead to obesity.
BMI is not always the best way for determination of ideal
weight in the case of body builders, children and elders.
BMI
percentile
“After BMI is calculated for children and teens,
the BMI number is plotted on the CDC BMI-for-age growth charts (for either
girls or boys) to obtain a percentile ranking. Percentiles are the most
commonly used indicator to assess the size and growth patterns of individual
children”
BMI
for age weight status categories and the corresponding percentiles are shown in
the following table.
Weight Status Category
Percentile Range
Underweight
Less than the 5th percentile
Healthy weight
5th percentile to less than the
85th percentile
Overweight
85th to less than the 95th
percentile
Obese
Equal to or greater than the 95th
percentile
“A child may have a high BMI for age and sex, but
to determine if excess fat is a problem, a health care provider would need to
perform further assessments. These assessments might include skin fold thickness
measurements, evaluations of diet, physical activity, family history, and other
appropriate health screenings.”
The Childs BMI
calculator provides BMI and the corresponding BMI-for-age percentile on a CDC
BMI-for-age growth chart. Use this calculator for children and teens, aged 2
through 19 years old.
BMI number is calculated the same way for
children and adults, the criteria used to interpret the meaning of the BMI
number for children and teens are different from those used for adults. For
children and teens, BMI age- and sex-specific percentiles are used for two
reasons:
·The amount of body fat
changes with age.
·The amount of body fat
differs between girls and boys.
See the following graphic for an example for a
10-year-old boy and a 15-year-old boy who both have a BMI-for-age of 23. (Note
that two children of different ages are plotted on the same growth chart to
illustrate a point. Normally the measurement for only one child is plotted on a
growth chart.
In the simplest terms anthropometry is measurement of the
human body; it helps in identification of under or over nutrition. It is also
used as a screening tool to evaluate adequate growth.
This is done by maintaining a growth chart, where height,
weight, age, head circumference, waist-hip ratio are all taken into
consideration. This can also be done by taking measurements and using
anthropometric tools and ratios such as, skin fold calipers and waist hip
ratios. This is then compared with the general height and weight standard of
the population. This helps evaluate if a person, child or adult is healthy and
adequately nourished.
Skin fold thickness helps estimate the subcutaneous fat.
(Fat that lies directly beneath the skin)
This is an estimate and hence doesn’t help with the
knowledge of one’s body composition.
Hence there are anthropometric body assessment techniques.
1.DEXA
Duel Energy X-ray Absorptiometry
This estimates fat free mass as well as lean mass.
It is used as a research in clinical studies even though its accuracy is very
good. However it causes radiation exposure.
2.Bioelectrical Impedance
(BIA)
This estimates the percentage of body fat depending
on conductivity of tissue fluid and electrolyte content by applying a small
alternating current. This method is not that accurate in measuring the body
composition of obese children. The benefits of BIA are that it does not require
a specially trained professional and it is a non-invasive method, comparatively
inexpensive when compared to MRI and DEXA. This is also available at small
house hold scales.
3.Ultrasound
This measures the subcutaneous fat percentage. It is
used in clinical and research settings.
4.Bod Pod
This works on the principle of air displacement.
This method is supposed to be very accurate in determining body fat
percentages, although it underestimates body fat in children. Hydrostatic
weighing is based on this similar principle but performed under water and hence
measures water displacement.
5.Total Body Electrical Conductivity
This is used to determine body composition and fat
free mass. This works on the principle of disruption of magnetic field by
electrolytes. This is quick method and there is no risk of radiation exposure.
6.CT and MRI
CT is Computed Tomography and MRI is Magnetic
Risonance Imaging. These are expensive methods to determine the body
composition, and requires trained
professionals. Unfortunately it causes radiation exposure. It is used in
clinical and research settings.
7.Deuterium
This measures total body water to further calculate
fat percentages. This is not a commonly used method because of the equipment
time and technicians it requires. It is also not radioactive and is used for
research purposes.
“The dietary transition
took place first in the industrialized world. For example, it is estimated that
the per person consumption of fat and refined carbohydrates has increased 5
to10 fold in England over the past two centuries, while the consumption of
fibre-rich grains has declined substantially” (1)
Whole
grain foods
Refined
foods
When eaten travels from mouth to stomach to
upper intestine, the rate of absorption is slow because of the fibre. The
glucose is taken up by the cells and is utilized for energy.
When eaten travels from mouth to stomach to
upper intestine, due to no fibre its rate of absorption is much faster.
Therefore there is a deposition of large amount of glucose in bloodstream,
glucose is taken up by the cells but there is more glucose than required and
so the excess gets converted into fat
refrence:
(1)Globalization, Diets and
Noncommunicable Diseases
Fat is a nutrient like
any other, it is therefore essential for maintaining good health. In excess,
fats cause a lot of damage to a person’s health. The term lipid refers to both
solid and liquid forms of fat. At room temperature fats that are liquid are known
as oils and the ones that are solid are known as fats such as butter.
The essential fatty
acids (EFA) are omega-3 (alpha- linolenic acid) and omega-6 (linoleic acid) and
Omega 9 (arachidonic acid). These cannot be synthesised by the body in any of
its chemical pathways therefore is required to be consumed through the diet.
EFA’s are also known as vitamin F or polyunsatureates. They are required for
cell structure and all body functions.
All omega fatty acids
are very important for the healthy function of our body: (5)
·Prevent
coronary heart disease
·Prevent
stroke
·Prevent
diabetes
·Promote
healthy nerve activity
·Improve
vitamin absorption
·Maintain
a healthy immune system
·Promote
cell development
“Excessive amounts of
omega-6 polyunsaturated fatty acids (PUFA) and a very high omega-6/omega-3
ratio, as is found in today's Western diets, promote the pathogenesis of many
diseases, including cardiovascular disease, cancer, and inflammatory and
autoimmune diseases, whereas increased levels of omega-3 PUFA (a low
omega-6/omega-3 ratio) exert suppressive” (6)
“The ideal ratio of Omega 6: Omega 3 is
believed to be 4:1 or lower. However, many diets, including most Indian
diets have a ratio of 15:1 or higher. This is because most vegetarian foods
such as oils used for cooking, fruits, vegetables and nuts common in the Indian
diet contain higher omega 6 than omega 3. Omega 3 rich sources, such as seafood
and flax-seed are not part of conventional Indian diets.” (7)
Imbalance in this ratio can be the cause
of many degenerative diseases, one of which is obesity. Omega 3 (Linoleic
acid) is vital as in the human body as
it can be converted to omega-3
(alpha- linolenic acid) and Omega 9 (arachidonic acid).
Both are good for are
health but in moderation, saturated and Tran’s fats are considered as unhealthy
as they increase bad cholesterol, which is the reason for many degenerative and
cardiovascular diseases.
Researcher Artemis
Somopoulos, MD, proposes the following “ideal” mix of fats.
Polyunsaturated fat (PUFA)
It is another type of
fat which when consumed lowers the level of LDL cholesterol but at the same
time can also lower HDL cholesterol.
Rich sources: Safflower oil,
sunflower oil and soya bean oil
Monounsaturated fat (MUFA)
Metabolically, it is the
best type of fat because when consumed lowers LDL cholesterol and elevates the
HDL2-4 cholesterol levels.
Rich sources: Olive oil, mustard oil and groundnut oil
However, currently, the
focus of research has shifted from saturated fats to individual fats and
percentage of fatty acids (SFA, PUFA, and MUFA) in the diet. An adequate intake
of both polyunsaturated and saturated fats is needed for the ideal LDL/HDL
ratio in blood, as both contribute to the regulatory balance in lipoprotein
metabolism.
What is the fat metabolism : as simple as it can get
Fats are packed into
lipoproteins in the small intestine
Lipoproteins are called chylomicrons
They help stabilization of
the molecules oflipidsin an aqueous environment such asblood plasma. Another function is to deliver dietary cholesterol to liver.
In the liver cholesterol are
packed into VLDL (very low density lipoprotein) for delivery to other tissues.
As VLDL travel throughout the body they give up lipids to muscle and fat cells,
as this continues they lose most of their lipids to become LDL (low density
lipoprotein)
LDL contains high quantity
of cholesterol.
The cells then take up LDL
through receptor mediated Endocytosis
In the cell there is LDL
breakdown that results in the formation of cholesterol, amino acids and fatty
acids. These components are then
used by the cell
HDL (high density
lipoprotein) is a lipoprotein that helps clear excess cholesterol from the
tissues and returns it to the liver for disposal, it contains fifty % protein
and hence is much higher density.
Body Fat
Body fat percentage studies
Storage fat and Essential
fat
Health is a matter of choice.
Obesity can be eradicated, all we need to do is educate ourselves to understand our food better. Did you ever imagine that your choice of oil could define your body?
*Cooking
oils for heart health, Sundeep Mishra,MD, S.C.Manchanda, MD*
Department
of Cardiology, All India Institute of Medical Sciences (AIIMS), New Delhi,
India*Department of Cardiology, Sir Ganga Ram Hospital, New Delhi, India
