Burn Body Fat With Morning
Aerobic ExerciseBy Tom Venuto - author of
Burn The Fat, Feed The Muscle -
for Ironman Magazine
An excerpt from Tom's article in
Ironman, August 2001
Even though morning aerobic exercise has
been embraced by bodybuilders as a "tried and true" fat loss technique, there
is definitely not a unanimous agreement about its effectiveness,
especially in the scientific community. Most competitive bodybuilders are
die-hard advocates of doing aerobic exercise first thing in the morning before
eating their first meal. They believe it will cause them to mobilize more
stored body fat and increase their metabolic rate all day long. There's quite a
bit of scientific literature supporting the a.m. fasted aerobic exercise
theory, but generally, the exercise physiologists and scientists tend not to
buy it. They subscribe to the energy balance hypothesis, which states; as long
as you burn more calories than you consume in each 24 hour period, then the
time of day you burn them doesnt matter, nor does whether you burn them from
fat or carbohydrate.
If you have even the most rudimentary
understanding of human physiology and physics, you have to concede that the
timing of your aerobic exercise is not the most important factor in fat
loss. When you do your aerobic exercise wont make or break you. Simply doing it
whenever its convenient and following a mildly calorie restricted diet is whats
important. However, theres a very strong case for doing fasted a.m. aerobic
exercise and if you want to gain every legal and ethical advantage possible in
your quest to get leaner then its definitely something you should take a closer
The argument in favor of fasted early
morning aerobic exercise goes something like this:
1. When you wake up in the morning after an
overnight 8-12 hour fast, your bodys stores of glycogen are somewhat
depleted. Doing aerobic exercise in this state causes your body to mobilize
more fat because of the unavailability of glycogen.
2. Eating causes a release of insulin.
Insulin interferes with the mobilization of body fat. Less insulin is present
in the morning; therefore, more body fat is burned when aerobic exercise is
done in the morning.
3. There is less carbohydrate (glucose)
"floating around" in the bloodstream when you wake up after an overnight fast.
With less glucose available, you will burn more fat.
4. If you eat immediately before a workout,
you have to burn off what you just ate first before tapping into stored body
fat (and insulin is elevated after a meal.)
5. When you do aerobic exercise in the
morning, your metabolism stays elevated for a period of time after the workout
is over. If you do aerobic exercise in the evening, you burn calories during
the session so you definitely benefit from it, but you fail to take advantage
of the "afterburn" effect because your metabolic rate drops dramatically as
soon as you go to sleep.
Research supports this theory. A study
performed at Kansas State University and published in Medicine and Science
in Sports and Exercise showed that a kilogram of fat is burned sooner when
exercise is done in the fasted state in the morning than when its done later in
the day. The researchers measured respiratory gas exchange, caloric expenditure
and carbohydrate and fatty acid metabolism, and found that the amount of fat
burned during aerobic exercise amounted to 67% of the total energy expenditure
in the morning after a 12 hour fast. This is substantially higher than the 50%
expenditure achieved when the same exercise was done later in the day or after
eating. A similar study from The Journal of Applied Physiology
looked at the effects of aerobic exercise on lipid oxidation in fed versus
fasted states. The researchers concluded, "our results support the hypothesis
that endurance training enhances lipid oxidation in men after a 12 hour
overnight fast." Yet another scientific paper, Optimizing Exercise for Fat
Loss," reports, "The ability of exercise to selectively promote fat
oxidation should be optimized if exercise is done during morning fasted
Despite the fact that increased fat burning
from morning aerobics seems logical and is backed by research, the majority of
scientists and exercise physiologists vehemently deny its effectiveness. They
are quick to point out that you can find a study to support almost any theory
you want to advocate. Interestingly though, even the most dyed in the wool
academics agree that youll burn more fat in the fuel mix as compared to
sugars. The real controversy lies in whether this fact has any impact on
overall fat loss in the long run.
Exercise Physiologist Greg Landry, MS,
author of "The Metabolism System for Weight Loss and Fitness," explains,
"I agree that you burn a fuel mix that is a little higher in fat if youre
exercising on an empty stomach. However, I think the real question is, does
that matter? I believe we have a pool of calories stored in different forms in
the body (fat, glycogen, etc.), so burned calories all come from the same pool.
Thus, it really doesnt matter that the fuel mix has a little more fat in it at
a given time. If its pulling from fat stores at that time, then its pulling
less from glycogen stores and thus future consumed calories will be a little
more likely to be stored as fat because glycogen stores are a little fuller. So
its all a wash."
Lyle McDonald, an expert on bodybuilding
nutrition and author of "The Ketogenic Diet," agrees. He argues that the
body will compensate later in the day and is simply "too smart" for strategies
like this to ever work: "All that research says is that you burn a greater
proportion of fat this way, which I agree with 100%," says Lyle. "The
majority of research shows that as far as real world fat loss goes, it doesnt
really matter what you burn. Rather, 24-hour calorie balance is what matters.
Because if you burn glucose during exercise, you tend to burn more fat the rest
of the day. If you burn fat during exercise, you burn more glucose during the
day. The end result is identical. If that werent the case, then athletes like
sprinters who never burn fat during exercise wouldnt be shredded. Basically,
they burn so many calories that they remain in balance and dont gain any fat.
So, while morning aerobic exercise probably provides some psychological
benefits to bodybuilders who are programmed to do it that way, I cant say that
I think it will result in greater real world fat loss, which is what
When it comes to "real world" fat loss, few
people have more experience than Chris Aceto. A successful bodybuilder and
nutritionist to some of the top pro bodybuilders in the world, Aceto is a firm
believer in morning aerobic exercise. He unequivocally states, "The fastest way
to tap stored body fat is to do aerobic exercise first thing in the morning on
an empty stomach."
Aceto believes that looking at calories only
in terms of energy in vs. energy out is "limited thinking." He asserts that
there are more factors involved in "real world" results than just energy
balance. This all comes back to the old argument, are all calories created
equal? "Absolutely not!" Aceto declares. "A calorie is not just a
calorie and exercise physiologists freak out when they hear this."
"These guys are working from the assumption
that its just a matter of calories in vs. calories out, period," Chris
continued. "With that line of reasoning, theyd be forced to say that if I
consume nothing but candy bars and Coca-Cola, and take in 100 calories less
than maintenance, Id lose weight. We know its not that simple. You
also have to account for ratios of carbs, protein, and fat. Then theres
meal frequency too: From real world results we know you put down more muscle
mass from 5 or 6 meals a day than from 3 meals a day. There are more things
involved than just calories."
Whether or not morning aerobic exercise in
the fasted state increases "real world" fat loss is still the subject of
controversy, but there are many other reasons you might want to consider making
it a part of your daily routine. Landry, despite his doubts about whether the
fuel source matters, admits, "If I had to pick a single factor I thought was
most important in a successful weight loss program, it would have to be to
exercise first thing in the morning."
Here are some of the additional benefits of
doing aerobic exercise early in the morning:
1.It makes you feel great all day by
releasing mood-enhancing endorphins.
2. It "energizes" you and "wakes you
3. It may help regulate your appetite for
the rest of the day.
4. Your bodys circadian rhythm adjusts
to your morning routine, making it easier to wake up at the same time every
5. Youll be less likely to "blow off"
your workout when its out of the way early (like when youre
exhausted after work or when friends ask you to join them at the pub for happy
6. You can always "make time" for exercise
by setting your alarm earlier in the morning.
7. It increases your metabolic rate for
hours after the session is over.
Of all these benefits, the post-exercise
increase in your metabolic rate is one of the most talked about. Scientists
call this "afterburn" effect the "excess post-exercise oxygen consumption" or
EPOC for short.
Looking only at the number of calories and
the type of calories burned during the session doesnt give you the full
picture. You also need to look at the increased number of calories you continue
to burn after the workout is over. Thats right - work out in the morning
and you burn calories all day long. Imagine burning extra fat as you sit at
your desk at work! Thats the good news. The bad news is, the degree of EPOC is
not as great as most people think. Its a myth that your metabolism stays
elevated for 24 hours after a regular aerobic workout. That only happens after
extremely intense and/or prolonged exercise such as running a marathon.
After low intensity exercise, the magnitude
of the EPOC is so small that its impact on fat loss is negligible. Somewhere
between 9 and 30 extra calories are burned after exercise at an intensity of
less than 60-65% of maximal heart rate. In other words, a casual stroll on the
treadmill will do next to nothing to increase your metabolism.
However, EPOC does increase with the
intensity (and duration) of the exercise. According to Wilmore and Costill
in "Physiology of Sport and Exercise," the EPOC after moderate exercise
(75-80%) will amount to approximately .25 kcal/min or 15 kcal/hour. This would
provide an additional expenditure of 75 kcal that would not normally be
calculated in the total energy expended for that activity. An extra 75 calories
is definitely nothing Earth shattering. However, it does add up over time. In a
year that would mean (in theory) you would burn an extra 5.2 lbs of fat from
the additional calories expended after the workout.
One way to get a significant post exercise
"afterburn" is high intensity interval training (HIIT). HIIT is done by
alternating brief periods of high intensity work (85% or more) with brief
periods of lower intensity work. Studies on the effects of HIIT have
demonstrated a much higher EPOC, which can add substantially to the days
calorie expenditure. In one study, scientists from the University of Alabama
compared the effects of two exercise protocols on 24-hour energy expenditure.
The first group cycled for 60 minutes at a moderate intensity. The second group
performed HIIT, cycling for two minutes at high intensity followed by two
minutes at a low intensity. The group that performed the HIIT burned 160 more
calories in 24 hours than the low intensity group. That means the HIIT group
would burn an extra 11.8 pounds of fat in one year if they did HIIT five days a
week instead of conventional training.
Ironically, weight training has a much
higher magnitude of EPOC than aerobic training. Studies have shown increases in
metabolic rate of as much as 4-7% over a 24-hour period from resistance
training. Yes - that means bodybuilding does burn fat albeit through an
indirect mechanism. For someone with an expenditure of 2500 calories per day,
that could add up to 100 - 175 extra calories burned after your weight training
workout is over. The lesson is simple: Anyone interested in losing body fat who
is not lifting weights should first take up a regimen of bodybuilding, then
and only then start thinking about the morning aerobic exercise!
A common concern about doing aerobic
exercise in the fasted state, especially if its done with high intensity,
is the possibility of losing muscle. After an overnight fast, glycogen, blood
glucose and insulin are all low. As weve already concluded, this is an
optimum environment for burning fat. Unfortunately, it may also be an optimum
environment for burning muscle because carbohydrate fuel sources are low and
levels of the catabolic stress hormone cortisol are high. It sounds like
morning aerobic exercise might be a double-edged sword, but there are ways to
avert muscle loss.
All aerobic exercise will have some effect
on building muscle, but as long as you dont overdo it, you shouldnt
worry about losing muscle. It's a fact that muscle proteins are broken down and
used for energy during aerobic exercise. But you are constantly breaking
down and re-building muscle tissue anyway. This process is called "protein
turnover" and its a daily fact of life. Your goal is to tip the scales slightly
in favor of increasing the anabolic side and reducing the catabolic side just
enough so you stay anabolic and you gain or at least maintain muscle.
How do you build up more muscle than you
break down? First, avoid excessive aerobic exercise. Aceto suggests limiting
your aerobic exercise on an empty stomach to 30 minutes, and then it would be
"highly unlikely that amino acids will be burned as fuel." He also mentions
that "a strong cup of coffee should facilitate a shifting to burn more fat and
less glycogen. If you can spare glycogen, youll ultimately spare protein
too." You might also want to consider experimenting with the thermogenic
ephedrine-caffeine-aspirin stack (or its herbal equivalent).
Second, give your body the proper
nutritional support. Losing muscle probably has more to do with inadequate
nutrition than with excessive aerobics. Provide yourself with the proper
nutritional support for the rest of the day, including adequate meal frequency,
protein, carbohydrates and total calories, and its not as likely that
there will be a net loss of muscle tissue over each 24-hour period.
Third, keep training with heavy weights,
even during a fat loss phase. Using light weights and higher reps thinking that
it will help you get more "cut" is a mistake: What put the muscle on in the
first place is likely to help you keep it there.
Still petrified of losing your hard-earned
muscle, but youd like to take advantage of the fat-burning and
metabolism-boosting effects of morning aerobic exercise? One strategy many
bodybuilders use is to drink a protein shake or eat a protein only meal 30-60
minutes prior to the morning session. The protein without the carbs will
minimize the insulin response and allow you to mobilize fat while providing
amino acids to prevent muscle breakdown.
In conclusion, it seems that morning aerobic
exercise has enough indisputable benefits to motivate most people to set their
alarms early. But lets talk bottom line results here: Does it really
result in more "real world fat loss" than aerobics performed at other times of
the day or after eating? I have to believe it does. Experience, common sense
and research all tell me so. Nevertheless, this will obviously continue to be
an area of much debate, and clearly, more research is needed. In the meantime,
while the scientists are busy in their labs measuring respiratory exchange
ratios, caloric expenditures and rates of substrate utilization, Im going
to keep waking up at 6:00 AM every morning to get on my Stairmaster.
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Venuto's Fitness Renaissance Newsletter
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Tom Venuto is the Fat Loss Expert
Tom Venuto is a bodybuilder, gym owner, freelance writer, success
coach and author of "Burn the Fat, Feed The Muscle" (BFFM): Fat Burning Secrets
of the World's Best Bodybuilders and Fitness Models. Tom has written over 150
articles and has been featured in IRONMAN magazine, Natural Bodybuilding,
Muscular Development, Muscle-Zine, Exercise for Men and Mens Exercise.
Tom's inspiring and informative articles on bodybuilding, weight loss and
motivation are featured regularly on dozens of websites worldwide. For
information on Tom's "Burn The Fat" e-book,