A frequently repeated phrase from the retreat earlier this year was "sperm & egg" referring to the significant impact that our genetic makeup has on our potential in most areas of our development. Here's another Christian Finn article that addresses the role of genetics on weight loss:
What you should know about genetics and weight loss
Part I:
http://thefactsaboutfitness.com/research/genetics.htm
The distribution of subcutaneous fat (the fat under your skin) is
also strongly affected by your genetics. This means two people
could follow exactly the same exercise program, but the loss of
subcutaneous fat would not be the same.
Research using identical twins also shows the rate at which
stored fat is broken down during a low-calorie diet varies
widely. This has an influence on the number of fat calories
your body burns for energy.
Just like a car, your fat cells have a series of brakes and
accelerators. The parts of a fat cell that accelerate the release
of fat are called beta-receptors. The parts of a fat cell that
slow the release of stored fat are known as alpha-receptors.
The distribution of brakes and accelerators on each fat cell
might help to explain why some people lose fat faster than
others.
One study, published in the Journal of Lipid Research, shows a
greater alpha-receptor response in overweight men compared to
lean men. However, it's not clear whether this is a consequence
(rather than a cause) of obesity.
Your genetics also determine where subcutaneous fat is stored.
Japanese scientists have identified three different "patterns" of
fat accumulation in young women in their early twenties.
The trunk and upper arm accumulation pattern. Fat tends to gather
on the whole trunk — chest, waist and back — and the upper arm.
In the waist accumulation pattern, fat gathers around the waist.
In the abdominals and hip accumulation pattern, fat gathers — as
you can probably guess — at the abdomen, side abdomen, hip and
lower hip.
The work of Bouchard and Tremblay suggests that there are genetic
influences at work. However, research by a group of Italian
scientists shows that a strong family history of obesity doesn't
make it inevitable you'll follow the same path.
A total of 16 young healthy men took part in the trial. The
parents of eight of the men were overweight. The other eight had
parents with a normal weight.
The men with a strong family history of obesity burned almost 50%
fewer fat calories in the eight hours after a meal than the men
with parents of a normal weight.
What's interesting is that the men with overweight parents
weighed about the same as the men with normal-weight parents.
That's despite the fact their genetics appear to put them at a
"high risk" of getting fat. In other words, your genetics may
load the gun, but it's your environment — the food you eat and
the exercise you do (or don't do) — that pulls the trigger.
The rapid rise in obesity over the past 20 years has occurred
despite a constant genetic background. The human body is exactly
the same as it was more than 10,000 years ago. Back then, most
people were relatively free of obesity and its related diseases.
Given the slow pace of human evolution, it's unlikely that your
genetic makeup has altered in such a way that it's now solely
responsible for the obesity epidemic gripping Western society.
Unlike the Windows operating system, a new version of the human
body is not released every few years. It takes tens of thousands
of years just for minor changes to your genetic makeup.
Significant changes can take millions of years.
Your body still "thinks" that it's living in a world that
requires you to hunt for food, walk 20-30 miles each day and
graze on food as you find it.
You won't be surprised to learn that muscle size and strength are
also under the influence of your genetics. Scientists have
isolated one particular gene that, through a protein called
myostatin, actually slows your rate of muscle growth.
Not only does myostatin affect how fast you gain weight, studies
on mice show that it can also slow the gain in fat that normally
occurs as you get older.
Myostatin is expressed in developing and mature muscle tissue. A
specific gene encodes for the transcription of the myostatin
protein, which is a "negative regulator" of muscle growth. In
simple terms, if you want to gain weight in the form of muscle,
the less myostatin the better.
Much of the early research on myostatin has been conducted in
animals. In mice where myostatin has been "knocked out",
individual muscles weigh twice as much as those of normal mice.
This increase in muscle size seems to be a combination of muscle
fiber hyperplasia (an increase in the number of muscle fibers)
and hypertrophy (an increase in the size of those fibers).
More interesting still, researchers from the University of
Maryland have shown that myostatin affects muscle growth in women
too. The study tracked a group of men and women taking part in a
weight training program for nine weeks. Muscle growth in the
quadriceps (the set of muscles in the front of your thigh) was
measured at the end of the study.
Analyzing the results, the research team found that myostatin
genotype didn't appear to be responsible for the different rates
of muscle growth between men and women (the increase in muscle
volume in the thigh was twice as great in the men). However, when
only the women were analyzed, muscle growth in those with the
less common myostatin genotype was almost 70% greater.
Variations in myostatin genotype could explain why some people
gain weight in the form of muscle far more quickly than others.
Muscle fibers in elite bodybuilders, for example, are often no
bigger than someone who has never picked up a barbell in their
life. Their muscles are larger because they contain a greater
number of small to average sized fibers.
Hyperplasia (remember, hyperplasia describes an increase in the
number, rather than the size of muscle fibers) may be more likely
to occur in bodybuilders with a less common myostatin genotype.
This could be one of the reasons — apart from drugs — they gain
weight so quickly.
Genetic variations mean that no two people will respond in the
same predictable way to the same program of diet and exercise.
Be realistic. If you have a body designed for long-distance
running, it's unlikely that you'll be winning the Mr. America
contest in the next few years.
All you can do is get the most out of your own body. There'll be
times when you see results very quickly. But there will also be
times when you feel like you're stuck on a plateau, and nothing
seems to be working.
Your genetics do have an influence on how easy or difficult you
find it to lose weight or gain muscle. But genetics are just that
— an influence.
The important thing is to stay committed to your goal, while
remaining as flexible as you can in the approach you're using to
get there. The right program of diet and exercise will make a big
difference to the way you look and feel, no matter where you are
today. What counts is where you end up, not how long it takes you
to get there.
To view this update on-line, including the full list of
references and a printable version, please visit:
http://thefactsaboutfitness.com/research/genetics.htm
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