I can see why Larry hardly posts here anymore. Been there, done that.
Swimming is notorious for not being nearly as good at weight loss as
land based exercise. Here's a partial post of his with references to
data which is over 7 years old.
This subject always comes up.
Here's what I wrote about it exactly 7 years ago, in one of the many
chapters
of this debate. I have found no reason at all to revise my thinking on
it...
RunnSwim Jan 8 1998, 12:00 am
Newsgroups: rec.sport.swimming
From: [email hidden] (RunnSwim) -
Date: 1998/01/08
Subject: Re: % body fat of swimmers
I've posted on this subject before, but Phil Whitten dismisses the
issue with too much certitude, so here's an r.s.s. replay as
a rejoinder:
In article <1998 [email hidden]>,
[email hidden]
(Swim Phil) said:In my book (The Complete Book of Swimming, Random House, 1994) I include data
on elite athletes in a variety of sports. Swimmers, male and female, have
among the very lowest. (They appear bulkier than, say, runners, because of
upper body -- muscular--development). More to the point, I print the results
of a survey I conducted of Masters swimmers (ie, adults age 25 to, I believe,
70+) by age group which shows: (1) swimmers have low body fat percentages;
(2)
there is very little, if any, increase in body fat as they age.
The notion that swimming might increase body fat is absurd!
.....
While in no way disputing the facts cited in Whitten's book, the
interpretation of those facts offered by Whitten is superficial
and misleading.
Swimming could increase body fat through the following mechanism:
Compared to running and cycling, swimmers burn more sugar and
less fat. Swimmers leave a workout more glucose and glycogen
depleted. This is a stimulus for eating. Swimmers tend to be hungrier
post workout than are runners and cyclists. Controlled studies
show that when fat content of post-workout meals are covertly adjusted,
there is greater caloric intake than calories burned when higher fat
meals are consumed. However, there is greater calories burned
than calories taken in when high carb/low fat meals are consumed.
Thus, swimming could theoretically result in increased body fat
were certain swimmers to unwisely eat high fat meals in the
post-workout, glycogen recovery period. There is a greater "risk"
of this happening with swimming than with running or cycling because
of the relatively greater amount of sugar burning, compared to
fat burning.
This issue is debated in the Dec 97/Jan 98 issue of Fitness Swimmer.
Noted swimming physiologist Costill agrees with me on this.
Actually, the evidence is completely consistent and quite
persuasive. For starters, the Gwinup study (abstracted below) was very
clear
cut.
60 moderately obese young (20-40) women. 20 did front
crawl and/or back crawl an hour a day 6 days a week for 6
months. 20 walked. 20 stationary cycled. Land exercisers
lost both weight and body fat. Swimmers lost neither. All
groups dropped resting pulse rate to the same degree,
confirming equal training effect. This doesn't apply to
serious masters competitors, but it certainly does relate to
what exercise you recommend to a young, moderately obese
woman, who wants to lose weight.
Costill studied competitive swimmers, cyclists, and
runners. Each did 40 minutes at 70% VO2 max (just sub
lactate threshold). Swimmers metabolized sugar almost
exclusively and emerged from the water glucose (and
presumably glycogen) depleted. Land athletes metabolized
substantial amounts of fat and less sugar.
This goes well with both evolution and muscle anatomy.
Upper body muscle is more "white muscle," with fewer
capillaries and mitochondria per unit volume. Also, total
volume is much smaller for upper body than lower body muscles.
Fat burning absolutely requires capillaries and mitochondria
(i.e. "red muscle," as it is exclusively aerobic). Cross
country skiers (who equally use and train both upper and
lower body), develop significantly more lower body aerobic
(capable of fat burning) capacity with training than do
their upper body muscles. This fits with evolution, were
lower body evolved to meet aerobic demands of migration,
hunting, and fleeing. Upper body activity was virtually all
anaerobic (sugar burning): i.e. spear throwing, tree
climbing.
True enough, elite swimmers are all thin and "ripped." But
this is selection, not causation. You can't make it to the
top without favorable passive drag. Likewise, Whitten's
surveys of runners vs. swimmers is selection and not
causation. No one who wants to lose weight will stick with
a sport where they do not lose weight. Contrariwise, obese
people who are losing weight will stick with a sport where
the weight loss is occurring, even if they do remain
overweight in an absolute sense. So you have a tendency to
lose obese swimmers who are swimming primarily to control
obesity, while you retain runners who are losing fat, even
though they haven't yet achieved slimness. People who
stick with swimming long term (like my 84 year old father,
who has been a competitive swimmer since 1920), are
obviously not those who are predisposed to significant
weight gain while doing it.
This also does not mean that it is not possible to lose fat
through swimming. Obviously, many do. The whole purpose of
trying to identify "problems," such as the "fat swimmer," is
that if one understands the problem, then one can develop
solutions to improve the sport, in this case as a weight
loss tool.
In the Fitness Swimmer debate, Laughlin says that
the way to do this is to avoid eating
carbohydrate for 10-12 hours before swimming and then to
swim for a long time at only 60% of maximum effort. I don't
agree at all with this. In the first place, the 60% effort
as continuous motion is probably pretty close to what
Gwinup's moderately obese young females were doing.
Secondly, the carbohydrate avoidance is exactly the opposite
of what a swimmer desiring weight loss should be doing.
This whole idea of eating fat to promote fat burning is
absurd. Sure enough, eat more fat and you will burn more
fat, no doubt about it. But you never burn more than the
extra dietary fat you are taking in. What does it profit a
swimmer to eat 3 extra grams of fat in order to burn 2?
What you would like to do is eat three extra grams of fat
and then burn 4, but that doesn't happen. And you can lose
fat by burning carbohydrate when you exercise; you don't
have to burn fat during exercise to lose fat. And eating
carbohydrates does not make you fat. There have been
many studies of high carbohydrate diets and not a single one
has ever shown weight gain, and most show weight loss, as
long as the diet is followed. And the world's largest
registry of people who have successfully lost 30 pounds and
kept it off for more than 5 years shows that the successfull
weight losers were primarily eating a high carbohydrate
diet. Sears says that the "fatterning of America," is owing
to eating less fat and more carbs. This is not true.
Between 1960 and 1976 average American calories as fat
consumption decreased from 39% to 36%. There was no
significant increase in obesity. Between 1976 and 1994, fat
consumption decreased further from 36% to 33%. Obesity
zoomed. But what also happened during this time was that
average TV viewing time increased to 4.4 hours per day per
person (cable TV, VCRs, Blockbuster Video), use of public
transportation (requires walking) fell significantly, school
children physical fitness scores plummeted on standardized
testing, and per capita sugar consumption increased by 20-30
pounds per year. Also huge numbers of people quit smoking.
What about insulin inhibiting fat mobilization and
inhibiting fat burning? Sure enough, it does this, but it is
very temporary. And carbohydrate gets converted to fat and
stored as fat at only 76% efficiency, while fat gets stored
as fat at 98% efficiency. And when you covertly adjust the
fat content of post exercise meals, you end up with a net
burning of calories when high carb food is eaten, but with
no net burning of calories (calories burned during exercise
minus calories taken in after exercise) when higher fat food
is eaten.
So what do you fear more, an "insulin spike" after a
carbohydrate meal which has a _temporary_ inhibiting effect
on fat burning, or a "fat spike" (i.e. postprandial
hypertriglyceridemia) in which extra fat is absorbed
(because extra fat is taken in at mealtime), which must then
be disposed of or stored (at 98% efficiency)?
What is the difference between having a high insulin level
for one hour or a high load of recently-absorbed fat for one
hour? Actually, the insulin goes promptly back to baseline.
The post-prandial triglycerides stay around longer, while
they are searching for fat cells to go hide in.
So here is really why swimming makes it tough to lose
weight...it doesn't really have all that much to do with fat
burning, per se, as it has to do with energy balance
(calories burned minus calories taken in after exercise).
Swimming burns sugar and leaves muscles glycogen depleted,
this is a powerful stimulus to hunger. Our club's age group,
USS senior, and masters swimmers talk about being
"famished" when they are getting dressed after their
workouts.
But walk from our club pool 200 yards over to the nearby
community college track and talk to the track athletes who
have just completed a typical workout of mixed intervals or
come back from a long run. The last thing they want to do
is eat a big meal. Why is this? Well, the swimmers have
depleted their muscle glycogen, and are hungry to replete
it. If they are foolish enough to try and replete it with
30% fat/30% protein/40% carbohdrate, they will be eating a
lot of unnecessary calories to try and build back up their
muscle glycogen. The track athletes, in contrast, have
burned less glycogen and more fat. Products of fat
metabolism (ketones) are appetite suppressing.
What the swimmers should do is to eat a nice high glycemic,
high carb, low fat snack immediately after getting out of
the pool. A nice plain bagel plus a banana or else a Powerbar
would do just fine. This will blunt the appetite response
and not ...
