Frequently Asked Questions
Question:
Swimming to Lose Weight: Fat vs Carbohydrate

Answers:
From: Larry Weisenthal
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, unit volume 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.

The old wives' tale that fat sends "I'm full" signals to the brain has been disproven by numerous studies of satiety following high fat vs high carb meals. It has been shown repeatedly that carbohydrate has superior satiety to fat and that when fat and carbohydrate content of foods are adjusted covertly, calorie intake increases as fat content increases and vice-versa.

This whole P*R Bar 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, 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 (U of Pittsburg) 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.

Barry 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 and army recruit 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. Did the Stanford women beat Texas because of the Zone Diet or because Mark Schubert moved to USC and was replaced at Texas by Jill Sterkel? Who won last year, by the way?

What about insulin inhibiting fat mobilization and inhibiting fat burning? Sure enough, it does this, but it is not absolute. 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 can make 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.

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 supply extra calories that do nothing to replete glycogen, which is the stimulus for the hunger in the first place.

And, as for the workout itself, it would be a very good thing to do lots of Total Immersion type drills, which involve a lot more lower body work (kicking), and less upper body work. In fact, the best fat burning TI drills are the pure kicking/balancing stuff. The trouble with combined upper body swimming and kicking is that the legs will prefer to use all of that lactate being produced by the upper body as fuel for aerobic metabolism, and not the fat that they would use if the upper body would just be kept quiet and wasn't producing any lactate. So the pure TI kicking drills are most effective at doing this, and will teach the swimmer good balance in the bargain. Other types of long kicking sets are good, as well. But you can lose fat with swimming, even without burning fat.

Basically, burn up all of the glycogen, and a high carb/low fat diet has a great chance to do what it does best. Those carbs have a place to go. There will be fewer excess carbs to hang around and get converted to fat (at only 76% efficiency, not at the 98% efficiency that fat is stored as fat). And the basal metabolic rate may be reved up and the body will be burning plenty of fat as the swimmer just goes about his/her daily activities. So you are burning more fat through a mechanism which doesn't require the intake of greater amounts of dietary fat. And it only takes a slight increase in fat burning, multiplied over 365 days a year, to result in gradual and sustainable loss of body fat. But the secret, swimming-wise, is not to ruin this great benefit through the consumption of more calories that results when you try to replete glycogen though a higher fat/lower carbohydrate diet.

This was posted ealier by a member of the board. It would be interesting to get feedback from those wiser than myself.

As a former competetive swimmer and a current biology teacher I can say that swimming and running made me equally "hungry". The one thing that swimming does is pull huge amounts of water out of the body, moreso than running. In addition to sweating during the workout (yes swimmers sweat), the chemical composition of the pool water also strips water from the body through osmosis. That is one of the reasons your fingers and toes get pruny and wrinkly looking after a long bath, swim, etc. For me a huge glass of water after a workout goes a long way to helping snub that hunger. Many times the body will read thirst as hunger pangs. Since many LC programs are naturally diuretic as well, a quick dip for some excercise will further dehydrate an athlete. Just my own opinion, a post workout meal with lots of fiber also helps to ease hunger and keep me from feeling hungry again before bed. I supplement my LC diet with extra fiber to make sure I am in the 20-30 g range every day. I don't know if this answers the question but I hope it helps provide some personal insight.

Happy LCing!
Katie

Katie, mind posting some links if you know of. I wanted know of
specific health benefit ,how different from running, energy
metabolism during swimming etc. swimming sounds like complete
body workout. Off late I had some sleep issue.

Doc. said you have two option, take pill or bump up exercise routine.
I smiled and thanked the doc. At leat this one is good and thinks
outside of pill I added swimming and sleep quality improved so
much .


I did google search.. did not find any great site.

neeam

I've been low-carbing for about 2 years, and I recently started swimming again, I swim about an hour at a time, at a leisurely pace, and I have to wonder, where is this sugar that swimming supposedly burns coming from, in my case?

I googled Larry Weisenthal and found that he has numerous anti-low-carb posts around the web. Most are on swimming related sites. He seems to be a high-carb addict.

Fact is, almost any exercise, short of a 100 meter dash, uses a combination of glycogen AND fat. Better trained endurance athletes tend to burn a little more fat. And so do low-carbers.

People who believe exercise relies only on glycogen and glucose are completely mistaken.

Back in 2002 when i add lower back pain and didnt quit know that my pelvic needed reajustement due to being an idiot and lifting 400 pounds squats and deadlifts with horrible forms.

I could not run, nor jump, nor do any other form of cardio without pain, and couldnt train at all.

So i started swimming and add gained a great amount of weight at that time, 231 pounds to be exact.

I started with 10 minutes and moved up to 30 minutes 5 times a week, anyone that has been swimming knows that its pertty intense.

I did the CKD at that time and swimming got me into ketosis real fast it was unbeleivable.

Right now i can train again and do stairmaster and cross country skiing machine, plus light weight training, and of course i still keep some swimming twice a week cause its a great exercice, and if you are sore from training, muscle sorness then swimming can really help un tense the muscles.

Swimming with a good mix of cardio and weight training will get you thin and even more important in great shape.

Great post btw and great subject.

Ok, this is all fine and good for the various types athletes who transform vast amounts of energy daily. Perhaps, because of the muscle groups involved in swimming, swimmers would be better served to garner the majority of their calories from sugar and not fat. Let's assume he is correct (even though I doubt he is - I am entirely sure those sugar-hungry muscles could at least partially switch over to ketone usage if forced to in a sugar-depleted state; I acknowledge performance might not be as good however).

What about 99.5% of the rest of the population? I don't see what relevance this has for the rest of us. The majority of human beings aren't even facing glycogen depletion. What impact do those "bagels and bananas" have on the rest of us? Where does all that quick fuel go? I'll tell you where, the sugar is stored as fat we can't even burn, leaving us with more adipose and low energy levels (reactive hypoglycemia).

Because we ate so much sugar before from the bagel and banana, this necessitated an abnormally high secondary insulin response. The author fully acknowledges this. Seeing as our glycogen is already full, and seeing as we won't be doing much exercise, the insulin turns sugar into fat. No problem you're thinking, you'll just seamlessly make the transition into fat burning and use up the energy that way! Wrong.

When insulin is high, the catabolic (body fat burning) hormone glucagon is low. You can't burn body fat in a hyperinsulinemic environment, it is physiologically impossible. Insulin is an anabolic hormone, insulin rises in the fed state. It acts on consumed energy to mobilize it for energy, use it for tissue building, store it as fat. The logic behind an elevated insulin level means there is (or your body thinks there is) more than enough energy being consumed. This is what your body thinks, so it will never raise the catabolic, tissue wasting hormone (glucagon) when it knows insulin is high. The problem is, modern high carbohydrate food (either selectively bred or processed) is not a natural part of the human diet. The insulin/glucagon axis did not evolve to handle it. Such foods overwhelm the body with so much energy in a relatively short period of time that it "fools" the body into thinking it is in a feast-state even when it might not be.

For example, say you drink a small snack of 120 calorie fruit juice. The fruit juice, despite its low calorie level, is absorbed almost immediately and entirely into the blood. Your body sees that 120 calorie cup of fruit juice, and it thinks you are positively GORGING yourself. You’re body has evolved to see that kind of rise in blood sugar and think "WOW look at how high our blood sugar is... this is really weird… we must be eating a TON of berries, nuts, and meat! What a feast! Better shut off glucagon to stop body fat burning ASAP!! Better raise insulin to store all this precious fuel for later!!"

Your body has no idea that you merely “spiked your sugar” with a processed fruit juice snack. It’s never seen the types of sweet fruits humans have selectively bred, nevermind their more refined higher glycemic state known as “fruit juice”. Your body also did not evolve to handle the added refined grain sugars consumed with the fruit juice. Your body was not designed to know what “high glycemic” or “high carb” is and how to handle it effectively. That your snack contained only a grand total of 120 calories, but as far as your body is concerned you must be gorging yourself on hundreds if not thousands of calories of meat, nuts, berries, low sugar fruit, and veggies. Your body was designed to assume that all foods are like the foods it evolved on, and therefore it has no efficient regulation mechanisms to handle rapid rises in sugar. Your body responds to this the only way it knows how. It responds as it would if it were in a feast state – it raises insulin, and shuts off body fat burning.

The author expects us to believe the body seamlessly regulates sugar levels; that the abnormal spikes in sugar are always so neatly handled by our hormones to keep energy balance evened out in the end. This is far from the truth. Even for relatively young, healthy human beings, high carbohydrate consumption is associated with energy highs (sugar rush) and lows (sugar crash). The high happens when sugar spiked (like when a kid eats some candy). The low happens when the sugar is all gone but the insulin/glucagon axis is still disturbed and out of balance (insulin levels are high, but sugar is now too low and because of the high insulin your body can’t switch over to fat burning… thus putting you in an energy-depleted state). The older you are, the more likely it is that you have or will develop significant intolerance to handle this unnatural diet. Genetic potential also plays a role – some human “families” have a better ability to handle it than others (hunter-gatherer type peoples have less tolerance for it, Europeans and Asians have slightly better tolerance). If high carbohydrate consumption were normal, this wouldn’t be. A higher fat, low sugar diet does not produce these energy level peaks and valleys. Everyone would be able to tolerate it, except in isolated instances of abnormality (genetic or environmentally induced). That’s not the case. Virtually every single human being has some problem with sugar. If nothing else, almost everyone feels more energetic and less dependent on consumption when they eat more fat & protein and less sugar.

I just got back from swimming a mile, fueled, as always, by my lowcarb diet. I've been swimming a mile a couple of times a week for about 30 years and I did not notice any change in my performance or energy when I switched to low carb eating two years ago (other than an increase in my energy level as I've dropped over 100 pounds). Granted, I don't swim particularly fast, but a mile is a good workout and if I needed lots of carbs to fuel it, I think I would notice.

I prefer to swim below water [Skin Diving, Snorkeling, SCUBA, and such,] but I also swim above water. Not all forms of swimming are all upper body. When you swim underwater you use mostly your lower body [legs.] You get the same effect when you swim on top of the water while wearing fins. You rely more on your legs and less on your arms than you would without them.

Most of the exercises I do work the Lower Body. As a result, I've got strong muscles in my lower body (Quadriceps/Calves/Hamstrings,) but not so much in my Upper Arms (Biceps/Triceps.) Regardless of how me or anyone else is built, one thing is for sure, like others have pointed out, how the body handles Carbs vs. Fat after an intense workout is not really relevant to most Americans.

As for the 76/98% or whatever the exact numbers were efficiencty rates, that's how well the body stores EXCESS food. Preferablly, you shouldn't be eating more than your body needs. Whether you get fat with 76% or 98% Efficiency really doesn't make much difference...because you still get fat. As long as you aren't eating way too much, how efficiently you can store excess doesn't even come into play. They never seem to mention the efficiency of using the fuels. Carbs are way more efficient in this department than Fat or Protein.

His statement about High Fat vs. High Carb and satiation is misleading, because most studies use misleading definitions:

High Fat usually means 35-40% Fat, and can even be as low as just over 30%. 35% seems to be the most common as that is about how much the Average American eats nowadays.

High Carb usually means VERY High Carb/VERY Low Fat. That would be about 10-20% Fat/70-80% Carbs/10% Protein. This would be on par with an Ultra-Low Fat Diet.

High Protein is about the only one they even come close to getting right at 20-30% Protein. But, unless the "High Protein" is paired with "Low-Carb," it usually means about 40-50% Carbs, and 20-30% Fat.

A typical "High Fat" diet in most studies would be something like 35% Fat, 50% Carbs, and 15% Protein. That is still too high in Carbs. 35% is also hardly High Fat. Here's what I would define them as:

Fat:

VLow -- <20%
Low -- 20-35%
Moderate -- 35-50%
High -- 50-75%
VHigh -- >75%

Protein/Carbohydrates:

VLow -- <10%
Low -- 10-20%
Moderate -- 20-30%
High -- 30-50%
VHigh -- >50%

What happens is when they study diets using a misleading definition, such as 35% Fat being a High Fat Diet, or 40% CHO being Low-Carb is that they get incorrect results. 40% is way too high to be Low-Carb...since that would be 150-280g Net Carbs per day, with most men falling at the upper end of that range. 35% is also too low to be High Fat at 60-110g Fat per day. The low-end of that range is barely more than the current USDA Recomendations...and the high end is just barely what I would consider a minimum fat intake (>90g) for a woman at the lower end of the Caloric Scale. What they're really testing is a Moderate Fat/High Carb/Low Protein Diet and calling it a High Fat Diet. What they call a High Carb Diet is a Very Low Fat/Very High High Carb/Low to Very Low Protein Diet. When you combine large amounts of Carbs with large amounts of Fat, you have problems that you don't have when you eat plenty of Fat and Protein without an excess of Carbs.

Oh my gosh, Larry Weisenthal, I used to debate him on Usenet probably 7 years ago when I was on the Zone! Hmm, I hope my writing ability has improved more since then than his has...

Anyway, I totally agree with ItsTheWoo that anything that applies to real athletes (whose bodies probably are different in many ways than mere mortals) can be pretty much disregarded by your average overweight person just trying to get their daily/weekly exercise in.

When I swim for exercise (not too often these days), I spend a significant number of laps with a kickboard, so that I can pull in more of those large muscle groups.

His article would have been reasonable had he not thrown in paragraphs 3 thru 9.

So less fat/more sugar is not an obesity culprit because obesity zoomed while fat consumption dropped a little and sugar consumption went up 20-30 lbs per year...

20-30 POUNDS?! additional?! You achieve that by chowing down with a sack of sugar for 18-27 full-calorie days. It's a great way to lower your physical fitness scores, too.