In a study of 10 men, skipping breakfast led to a dip in athletic
performance hours later, even after a larger lunch.
Despite the bigger lunch, skipping breakfast led to a slightly lower
overall calorie count for the day. But if weight loss is not the priority,
researchers say, forgoing breakfast might backfire by reducing the
effectiveness of the day’s workout.
“Many athletes as well as recreational exercisers do so in the evening
and breakfast skipping is a relatively common dietary practice,” said senior
author Dr. Lewis J. Jamesof the School of Sport, Exercise and Health Sciences
at Loughborough University in the U.K.
“Whilst we know that consuming breakfast is likely to be the best
dietary strategy in most situations to maximize exercise performance in the
morning, we did not know how or if breakfast skipping/ consumption influenced
evening exercise performance in a situation where the exerciser ate lunch,”
James told Reuters Health by email.
The researchers had 10 men who were regular breakfast eaters complete
an evening athletic trial twice, once after eating breakfast in the morning and
once after skipping it.
The men arrived at the lab having fasted overnight and either ate a
breakfast of about 700 calories or did not. They then ate lunch about four hours
later and dinner about 11 hours later, and the researchers kept track of how
much the men consumed at each meal.
Between lunch and dinner the men performed an exercise trial of 30
minutes of steady-state cycling at 60 percent of their max effort followed by
another 30 minutes of a performance test, when they were told to push
themselves as much as possible during the remaining time.
After they completed the exercise test and had eaten as much of the
provided pasta dinner as they liked, they were transported home and told not to
eat again until the next morning, when they returned to the lab to be weighed
and complete appetite questionnaires.
On days when they skipped breakfast, the men consumed an average of
almost 200 more calories at lunch compared to days when they ate breakfast, but
total calorie intake tended to be lower on days without breakfast.
Average heart rate and total fat oxidation during the cycling test was
greater after skipping breakfast compared to after eating breakfast.
The men worked harder, expending marginally more calories, on days when
they had eaten breakfast, as reported in Medicine and Science in Sports and
Exercise.
“Skipping breakfast reduces the amount of available energy (glucose)
for muscular activity and therefore it would be important to know if this had a
functional consequence – i.e. reduced performance,” David Levitsky, a professor
of nutrition at Cornell University in Ithaca, New York, told Reuters Health by
email.
But the difference in performance was quite small, and may depend on
the kind of exercise, he said. Some kinds may be impaired by skipping
breakfast, others may not, said Levitsky, who was not part of the new research.
Although it impaired performance, skipping breakfast or exercising with
suboptimal carbohydrate status might enhance training adaptation in some cases,
so sometimes it can be the right choice, James said.
The findings indicate that skipping breakfast could be used as a
strategy to reduce overall energy intake, in habitual breakfast consumers at
least, where weight management is the key goal, he said.
“I would add a word of caution and say that weight loss will depend on
the balance of energy intake and energy expenditure and if skipping breakfast
resulted in more feelings of tiredness and reduced physical activity over the
day this might attenuate the energy deficit created by skipping breakfast,”
James said.
This was only a small study of 10 men who were all fairly similar, he
noted.
“Certainly more work is needed to see whether the effects persist in
other populations,” he said.
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