Originally Posted by yannick

I am using swimming has my main exercice right now and i stumbled on this article today on the net.

Now i am doing the CKD and find it works fine, i dont like most of what they say in the article but have decided to post it anyways to have some feedbacks.

This week i was in ketosis very fast after swimming 20 minutes in the morning, it took me around 30 hours to hit ketosis after a lot of junk food eating and fructose.

So my guess is that swimming doesnt burn has much fat has running can speed up entry in ketosis so might be even better.

Here is the article, i dont agree with the high carb diet thing.

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.