Download Chapter 2: Healthy and Active Lifestyles

4HEALTHY AND ACTIVE LIFESTYLES
2
Factors that will raise your BMR
Diet
Activity
Outcome
If energy in equals
energy out
then body weight is maintained over time.
If energy in is greater than
energy out
the body will store this excess energy as body fat.
If energy in is less than
energy out
the body will use stored fat as energy and fat loss will occur.
Factors that will
lower your BMR
Despite these claims the facts are outlined in Table 2.1.
The act of digestion requires energy to break down the
food and convert it into usable nutrients. The key is lots
of small meals throughout the day
Exercise
This will increase the need for energy during the activity,
and depending upon the intensity, duration, time of
day and type of exercise undertaken may also lead to an
elevated BMR for several hours after exercise
Rate of fat loss
Muscle mass
Muscle is a fat hungry tissue and requires more energy
than other tissues even at rest
The rate of fat loss should be steady and slow, and
1-2 pounds of fat loss per week is considered a good
rate. A slow rate such as this is sustainable over a long period because the body is able to adapt to any changes. As a result these losses tend to be more permanent.
Age (up to peak physical maturation,
mid 20s)
Increase in lean muscle mass
High levels of natural growth hormone and anabolic
steroids
Apply it!
Vigorous cycling will burn between 500
and 700 calories per hour. There are 3200
calories in one pound of fat (or 7040 calories
to 1 kg of fat).
Assuming an average of 600 calories is the norm,
calculate the appropriate amount of time in days
or weeks that it should take a 14 stone man to get
down to 12 stones in weight (a loss of 12.72 kg).
Explain your result.
• The body loses fluids which are essential for efficient
functioning, resulting in lethargy and demotivation.
• The body will automatically assume that it is
enduring a famine and will:
a. become more efficient at surviving on less fuel. It will use less calories than before to carry out the same activity
b. hold on to what it considers to be the most
essential elements, such as fat, and lose the nonessential elements such as lean muscle mass!
c. ensure that muscle burns fewer fat calories even
at rest in order to conserve the supply of fat stores
d. lower the basic metabolic rate (BMR).
Remember
Take it further
If your weighing scales say that you have
lost ‘6 pounds of weight this week’ have
you really done 36 hours of cycling or
the equivalent?
If calorific restriction is used in an attempt to reduce
body mass then initially weight will be lost, but the
rate of weight loss will eventually slow down and
then stop altogether until the calorific content is
reduced further. However, while this is happening
you will probably be encouraged to continue
because the weighing scales indicate that you are
losing weight. It appears to be working. While the
number of calories are being reduced the following
things are happening in your body:
4 24
Age (after peak
physical maturation,
early 30s onwards)
Tall, thin people have a higher BMR
Getting pregnant
The growth of the unborn baby and the changes taking
place all require significant quantities of energy
Environment
Extremes of both hot and cold temperatures require the
body to work hard in order to maintain a balanced body
temperature
Hormones
Fasting/Starvation
The body hoards what it has
Hormones
Thyroxin produced by the thyroid can raise or lower BMR
by 50%
large cheese burger, fries and a strawberry milk
•A
shake contains 1330 calories.
Smoking/Caffeine
If caloric restriction is
too severe:
If body weight loss is
too rapid, some fat is
lost, but:
Loss of significant
amounts of lean tissue is
likely (muscle and bone
nutrients).
Overall nutrient intake is
less likely to be balanced.
It might initiate a habit of
binge eating.
Large amounts of fluid
are lost.
Some lean tissue is lost.
Table 2.2 Dangers of restricting calorific intake alone
Decrease in muscle mass
More likely to be sedentary
Less growth hormone and anabolic steroids produced
Height
KEY TERM
basic metabolic rate (BMR) the rate at which calories are burned
Reason for increase
Eating frequent meals
Table 2.1 The three energy expenditure statements
3
HEALTHY LIFESTYLE
Raises energy expenditure
Sleep
The body is at its least active and so requires less energy
Table 2.3 Comparison of high and low BMR
Simply cutting back on the amount you eat will not
be enough to help you if your goal is fat loss. You
will hold on to the fat, lose muscle tissue first and
slow your metabolism down. It will be easier for you
to gain fat at a faster rate if you ever resume your
previous eating habits.
Basic metabolic rate
successful fat loss is to maintain a high BMR. People
with a high BMR are usually thin, while people with
a low BMR are usually carrying excess weight in the
form of fat.
Exercise is seen as offering significant positive
benefits to many of the contemporary concerns
identified earlier.
Your basic metabolic rate (BMR) is the speed at
which your body converts and uses calories to fuel
the activities that you undertake. One of the keys to
25 3