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Does Cardio Make You Fat

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Does Cardio Make You Fat?
Some people say that cardio will make you fat.
This is not true. Cardio does not directly cause you to gain fat. You
gain body fat when the energy that is entering the body is greater
than the energy that is leaving the body.
There are certain situations in which doing cardio exercise along
with other behaviors can increase the likelihood that someone will
gain body fat. But it is very important that everyone understand that
cardio is not directly causing this to occur.
It is true that in this article we wrote, “aerobic exercise is a fat
trap.” It is completely reasonable that the average reader could
interpret this to mean that aerobic exercise—which is generally what
people mean when they talk about “cardio”—makes you fat.
For the sake of preventing further confusion, let us clarify the
statement with points from the literature:
• We know from a 2011 review by Boutcher that "the effect of
regular aerobic exercise on body fat is negligible." Sprint intervals
work better.
• Over the long-term, cardio leads to the loss of lean muscle mass,
which reduces the amount of calories burned by the body at rest
(Westcott, 2009). If one doesn’t reduce calorie intake at the same
rate, fat gain occurs.
• According to a 2009 review by Boutcher, short-term aerobic
exercise studies designed to reduce body fat are “disappointing”
because they produce less than expected fat loss.
• A 1997 meta-analysis by Miller of 493 studies showed that
changing diet is a much more effective way to reduce body fat than
doing cardio in overweight people.
• The purpose of aerobic exercise is to train the body to be as
efficient as possible. The body adapts quickly to repetitive aerobic
exercise with the goal of using the least amount of oxygen and
energy to perform the greatest amount of work. This does not
promote fat loss.
See this effect in action with Williams’ 2006 survey of 12,568
runners in which only those who increased their weekly distance or
running speed over the 9-year study did not gain fat. Those who
maintained or slightly increased mileage and intensity had larger
waistlines by the end of the study.
All this evidence is just the tip of the iceberg indicating that cardio is
not a very useful form of exercise for losing body fat. It begs the
question:
Why do some people gain fat even though they do cardio, and how
can this be avoided?
The following ten rules will answer this question and help you to
experience all of those good things that can come out of exercise: a
perfect body composition, boundless energy, and a workout
program you don’t need to stress about.
#1: Aerobic-style cardio is most effective if you are overweight
and new to exercise. A number of things relevant to fat loss occur
when you first start doing cardio:
• You burn calories during the workout and during the postworkout recovery period.
• Your body increases its ability to burn body fat and to switch
between fat burning and carb burning—an adaptation that is highly
beneficial for fat loss.
• Insulin sensitivity improves and your body uses the sugar in the
blood more effectively.
Depending on the intensity and length of workouts (75 percent of
maximal heart rate for 40 minutes is often used in studies), you can
expect to lose 1 to 2 kg of fat in 3 to 4 months, assuming you don’t
change your diet.
A review of studies reported that cardio interventions of at least 15
weeks led to about 1.5 kg of fat loss, and lean people tend to lose
less fat than overweight folks.
#2: Eventually, the body adapts and uses energy and oxygen
more efficiently during cardio, making it less effective for fat
loss. Workouts will feel easier and if you want to continue
experiencing the same metabolic benefit, you have to either
increase intensity and train faster, or increase the distance.
For example, scientists estimate from calorie balance equations that
it would require upwards of 1 hour of moderate-intensity cardio 7
days a week to produce continual fat loss to the tune of about 1
pound a week in active individuals.
Even this enormous volume of exercise will lead to diminishing
returns in the long run because muscle mass will be lost. Plus, the
repetitive exercise stress could lead to altered hormone balance.
Further, calorie balance equations do not prove to be very
applicable to real life situations.
#3: Too much cardio can lead to increased hunger and food
intake, which leads to fat gain. Not only do people often eat more
when doing cardio, misconceptions about how to “fuel” exercise
have led people to eat high-glycemic foods before, during, and after
exercise, which suppresses fat burning.
Light and moderate intensity cardio such as walking, jogging, or a
bike ride won’t significantly deplete energy stores or cause muscle
damage, and extra protein or carbs aren’t necessary and may
negate a calorie deficit. Plus, both cause the release of insulin,
which is not ideal when the goal is fat loss.
There’s even evidence that some people reward themselves for
exercising by eating carbohydrate-dense, high-fat foods, which
leads to fat gain.
#4: Doing cardio to lose fat in conjunction with calorie
restriction leads to weight cycling. People initially lose fat and
muscle. Then when they increase calories and stop dieting, they
gain the fat back. They also replace the lean muscle that was lost
with fat.
This is a worse body composition, which means their body will burn
fewer calories at rest, and it increases disease risk. For example,
people who do cardio with repeated diets in the hopes of losing fat
have more inflammation and a higher risk of heart disease than
people who don’t diet or exercise and remain the same weight.
#5: People with elevated cortisol from chronic stress are less
likely to lose body fat from cardio because high cortisol causes
the body to store fat. Here’s what happens when cortisol is high all
the time:
• Cells become resistant to insulin, causing inflammation, and
making body unable to access body fat to burn for energy.
• The hormones that regulate hunger can become imbalanced.
Compared to people with normal cortisol, people who suffer more
stress and have high cortisol have 15 percent higher ghrelin, which
triggers hunger, and 15 percent lower leptin, which suppresses
hunger.
• High cortisol makes people favor high-sugar foods to replace the
neurotransmitter serotonin, which is depleted during chronic stress.
• Growth hormone (GH) and testosterone (T) are suppressed,
which is associated with fat gain, particularly in the belly and trunk
area.
Therefore, a few things are indicated if you have high cortisol and
want to reduce body fat. First, you have to adopt stress reduction
methods (focusing on sleep, supplementation, meditation, fun
activities).
Second, fix your diet by choosing lower glycemic, whole foods.
Third, try strength training instead of cardio as your main exercise
mode because it can help to balance cortisol with other hormones
like GH and T, while improving insulin sensitivity.
#6: High cortisol combined with cardio produces changes in
the body making fat gain more likely. The simple act of doing
cardio can increase cortisol.
In normal circumstances this is not a problem and the cortisol
release will be transient. Remember, healthy, sedentary people who
start to do cardio will improve insulin sensitivity and fat burning.
They are likely to lose some fat as well.
But, combine the cortisol spike from daily cardio with an elevated
cortisol curve due to stress, and you have a fat trap. This is most
likely to happen with higher intensity or longer duration cardio
workouts. Also, fasted, intense training can cause elevated cortisol,
whereas going for a walk, or other casual exercise is less likely to be
a problem.
The bottom line is that you could end up gaining fat even though you
do cardio if you have high cortisol because you might end up eating
more than you intend or being less physically active so you burn
fewer calories over the course of the day.
#7: Anecdotal reports suggest women tend to have a greater
difficulty losing body fat from cardio than men over the longterm. A few things make this more likely to happen:
We’ve already established that if you experience weight cycling from
calorie restriction and cardio, you’ll progressively reduce muscle
mass and have a lower metabolic rate. Women are especially
susceptible because they start out with lower muscle mass to begin
with.
Women may be at a greater risk of experiencing elevated cortisol in
response to repetitive training stress because hormone balance may
be more delicate. High cortisol from excessive training stress will
cause a woman’s body to shuttle the hormone pregnenolone into
cortisol production instead of using it to make progesterone, which is
a hormone that facilitates the use of fat for energy.
In turn, this reduces estrogen and testosterone, which need to be
balanced for optimal metabolic health in women.
#8: Cardio interferes with muscle building. This is a well-known
fact in sports science:
When endurance athletes lift weights, they get stronger and
increase the size of the Type II muscle fibers, but they rarely gain
muscle mass. They will often lose body fat as well with the addition
of strength training, which produces a much more favorable body
composition for endurance performance.
A recent study illustrates this. Researchers had both young
untrained men (Strength group) and a group of elite cyclists
(Cyclists) do a strength training program. The Strength group did no
cardio and the Cyclists did their regular aerobic training.
The Strength group gained about 1 kg of muscle, whereas the
Cyclists gained zero. In addition, the Strength group increased quad
and hamstring cross-sectional area by 50 percent more than the
Cyclists.
Scientists believe aerobic type cardio "turns off" muscle building
pathways and promotes catabolism, inhibiting muscle development.
It’s also possible that the high volume of exercise required from both
cardio and lifting workouts led to elevated cortisol, further impairing
muscle growth.
Therefore, if you’re trying to build muscle, which is absolutely the
best plan for reducing body fat and keeping it off, don’t do steadystate cardio.
#9: Interval training is more likely to produce fat loss than
cardio, and it will allow you to save training time because it
builds lean muscle mass.
An abundance of studies show that the many versions of highintensity training, such as sprints, circuit training, strongman, and
even more moderate intervals are all better choices for fat loss than
steady-state cardio for the following reasons:
• You burn more calories in less time. Depending on how hard you
push during the intervals, you can burn more calories in just 25
minutes than you can in double that time when doing cardio.
• You experience a more robust energy expenditure in the 24-hour
post-workout recovery period than with cardio because your body
requires a lot of extra energy to restore metabolic balance and
remove waste products.
• Genes involved in protein synthesis (muscle building) are turned
on and you will be more likely to experience a better hormonal
environment post-workout, with an elevation in GH and testosterone
along with cortisol. This allows interval training to sustain lean
muscle mass and may even build muscle for a better metabolic rate.
#10: Strength training is a superior form of exercise that will
allow you to be satisfied with your physique.
It optimizes lean muscle mass, elevates metabolic rate, and
improves insulin sensitivity. It also improves hormone balance,
reduces inflammation, and supports cardiovascular health.
Take Away Points:
• Prioritize diet, lifting, and stress management if your goal is fat
loss. Add in some form of intervals to accelerate results. The optimal
intensity for your intervals will vary based on individual factors such
as stress levels, carb intake, gender, age, training background, and
so forth.
• If your only goal is to build muscle, avoid cardio completely.
Focus on putting your energy into lifting and strongman workouts.
Prioritize diet and recovery.
• If you are passionate about endurance exercise but need to lose
fat, replace some of your steady-state cardio workouts with
moderate-intensity intervals. Add strength training to your activities.
• If you are training for an endurance race and want to improve
performance, do a strength-type lifting program with heavy loads (80
percent of the 1RM or heavier) in order to optimize body
composition.
• If you are a power athlete, avoid cardio because power is the
performance variable that is MOST compromised by steady-state
cardio—much more than strength or hypertrophy.
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