The Carb Question

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Thoughts on low carbohydrate diets in conjuntion with triathlon training.

It's tough to find a person who has not heard about the miraculous weight loss secrets of a low carb diet. From the Atkins Diet to the South Beach Diet, everyone seems to be going low carb. And for most, the results seem to be a success - at least the ones we hear from. Even medical research seems to be supporting some of the claims of low carb followers that this type of diet, which ends up being a rather high protein and fat diet initially, reduces a lot of the markers of heart disease such as improving blood lipid profiles and reducing triglycerides.

But not everyone is torching the potatoes in the pantry. In fact, some research indicates that a low carb diet can actually cause some negative responses in the body similar to that
found in a person who is under constant long-term stress. And for an athlete, especially someone who is training for any kind of endurance event, the effects of a low carb diet leaves him or her feeling sluggish and unable to recover or perform at any level that would be considered optimal.

Let’s look a little deeper into what is going on in the body to find out what gives the health improvements people are after. At the same time, let’s look at what might be behind some of the negatives showing up in athletes who do not have a good enough base of health to undertake such a regime.

The Weight Loss

There are three reasons why a low carb diet results in weight loss. The first is a chemical reason. Carbohydrate is stored in the body along with water molecules.  (This is one reason why carbohydrate loading, a process where one cuts out carbs completely for three days, then super loads them for three more, can have such a positive effect on endurance performance. Not only does it cause an athlete to store up more of this precious workout fuel, but in addition to carbs, the athlete will store up additional water molecules that get released when the carbs are broken down.

As far the low carb diets go, they all have an induction phase in common during which all but the lowest glycemic carbohydrates like vegetables are cut out. The reason for this initial period is purported to be to help reset the person's metabolism to start burning fat. But on the motivational level, people will lose a lot of weight very quickly in these initial weeks simply because they are burning up the stored carbohydrates, which then releases
stored water into the system. This water is either used by the body or excreted. In either case, the end result is a big initial drop in weight purely from water loss. In fact if you are losing more than about 1.5 pounds per week, it is either because of the water loss due to carb restriction or it is because you are starving your body with too few calories, in which
case you are losing both fat and lean muscle, which is absolutely not good for long terms health.

After this initial phase, small amounts of carbs are added in until a person finds they plateau in weight, at which point they must drop back down on the carbs once again until weight loss continues. The "low carb" that the diets recommend for people after they reach their goal weight is in actuality a balanced carb approach. But most people need to restrict something in their diet to get down to their goal weight, and the easiest and perhaps most
effective culprit to cut out is indeed the carb.

This is an oversimplification of the process, but essentially it describes the plan. The cutback in carbs is supposed to increase metabolism away from carb burning and to stimulate fat burning. We know the reverse happens in a high carb diet. Excess carbs cause an insulin spike, which indeed does turn off fat burning. Excess carbs shut off fat burning and cause sugars to be stored. This means that the only way to get blood glucose levels back up once insulin has done its job is to eat more carb. This is the vicious sugar
cycle of craving that causes a person on a high carb diet to always feel hungry and to overeat.

Excess carbohydrates in a person's diet get stored in the liver and muscle as glycogen. They also get converted into fat for deposit at the unsightly places on a person's body. This of course is one thing that the low carb diet will correct. A low carb diet will shift the metabolism back toward fat burning, which in theory will reduce body fat. Keep in mind that by restricting carbohydrate intake, most people end up reducing their overall daily calorie intake. So while these diets do indeed increase fat burning, a lot of the weight loss is due to a simple reduction in overall calorie intake.

Protein on the other hand helps increase fat burning and helps stabilize blood sugar levels, which reduces food cravings. Fat has the effect of turning off the part of the brain that tells you that you are hungry. So eating a higher amount of protein and fat in one's diet will naturally shut down the food craving cycle that carbs can set up, with the result of
helping a person cut back on their overall daily calorie intake.

So you can see that a low carb diet works to both decrease your feeling of needing more food and helps shift your metabolism toward fat burning rather than shutting it off like a high carb diet will.

Not All Bodies are Created Equal

This is good in theoretical terms for weight loss. However, there are some problems that we can see if we dig a little deeper into the low carb physiology. The first is what happens in your body when you put it under a restricted carbohydrate intake. This is not a normal state, and your body perceives it as a stress. This causes the release of one of the major stress handling hormones called Cortisol. The release of Cortisol is normal and
fine if you are not under other stresses already.

However, if you have been under prolonged stress either emotional or chemical (like a high carb diet will cause), Cortisol is already present and adding the low carb stress will increase this even further. Some of the things that happen under high Cortisol levels at this level are that fat burning is turned off, carb burning is increased, emotional distress is
increased, and a general increased perception of life as a stressful situation ensues. This causes even more stress in the body and even more Cortisol to be released, which keeps you in the stressed state where among other things fat burning is turned off. None of this helps give you what you need to stick with a restricted diet, even for a short time, and it is not healthy for your body.

If you feel you have been under a lot of stress for a long period of time or if you also know you have overdone your carb intake, a less stressful and more effective way to get down to a healthy carb level is to cut back gradually over several weeks instead of the cold turkey approach of most low carb diets.

A second problem with a low carb diet has to do with what an athlete needs for working out. Basically, low carb does not cut it. Carbohydrate is needed for energy, both for high-end efforts and for aerobic fat burning efforts. Without sufficient stored carbohydrates in the muscles and liver, when you go to work out, you will not have it to draw on and your body will go once again into a stressed state releasing Cortisol, which as was stated is a
negative over the long haul. So while a low carb diet might work for a sedentary individual, if you are a regular at the club or on the trails, you would be better served to make sure you get at least enough carbs to get through your workouts at a high level.

The way a carb is stored is also important for an athlete to consider. A little insulin is required to store carbohydrate. If you have depleted your carb stores with a long workout or through a low carb diet, you will need to get a carbohydrate back in if you want your next workout to go well. It has been shown that very complexed carbohydrates often cannot get this job done because they do not cause enough of an insulin release to store sufficient amounts of carb to fuel your next training session. It is therefore actually beneficial to get a moderate insulin response through the food you take in, especially just after the workout, to be able to replenish for the next one. This is not to say that it's time to go chow down on a piece of cake and get an insulin spike. An insulin spike is very different than an insulin response. But it is saying that eating a few vegetables probably will not get you ready for a great workout the following day.

Does Normal Carb Work?

You may be wondering if it is possible to lose weight, workout great, and eat a normal carb diet. The answer is absolutely yes. The real quest is to make sure that the amount of calories you eat each day is roughly equal to the amount that you burn throughout the day. And if losing weight along with a great workout is your goal, a reduction from that level of about 500 calories per day will do the trick over time. Of course, it is important to
get a good balance of carb, fat and protein. But even a low carb diet that is too high in overall calories will cause weight gain.

The reverse is true, and we can look around the world to see it. In India, the average person's protein intake is only about 15% of their total daily calories. However, obesity is hardly a problem. The reason is that most of the carbs are in a good form that do not cause an insulin spike (lentils and rice is one example). Their total daily calorie intake is low, yet many also have very physical lives. And the reason that even with a relatively high
percentage of their total calories coming from carbohydrates that there in not a weight issue is because the overall food intake is in line with the caloric expenditure throughout the day.

Let me put this all together in a few points for you:

The Pluses

- A low carb diet (high protein and fat) will help to stabilize blood sugar and reduce carb cravings and frequent feelings of being hungry.

- A low carb diet helps an individual restrict calories better than cutting back on either fat or protein alone, which results in weight loss.

- People often feel energy because they are not being stuck in the blood sugar swings of a high carb diet.

The Negatives

- If you are under stress, a low carb diet will cause more stress and further destabilize your system.

- If you are an athlete, a low carb diet will not provide you with enough stored fuel calories in the form of glycogen to workout efficiently. It will also put you in a stress state if you are not getting enough carbs to cover your energy expenditure during exercise.

What You Can Do:

- If weight loss is an issue and you cannot structure a way of eating that reduces your overall caloric intake, then a low carb diet is worth trying.

- If you have not tried to cut back on intake before, it is better to start with an overall assessment of your diet. If you eat a high amount of simple carbs, you might find that exchanging these for more complexed forms of carbohydrate will be enough to get you the results you are after without the structure (and risk of body stress) of a low carb diet.

- If you are an athlete who watches what they eat but still cannot lose weight, look at the way you do your workouts. Too much anaerobic (speed) training will shut off your fat burning mechanisms and it will be very difficult to lose the weight you are after even if you are on a low carb diet. First try reducing your workout intensity for several months and
use a heart rate monitor to regulate your effort instead of your ego. This will help increase fat burning and change overall composition in your favor.


- One is the Weight Watchers program that has been around for years and provided a simple way for people to easily cut back on calories, but still maintain the percentage of carb, fat and protein that will work for them.

- Another is a book called The Schwarzbein Principle II, The Transition. This addresses the differences in people's stress levels and helps them adjust the transition from high carb out of balance diet to one that is a moderate carb in balance way of eating.

Best of luck with your training and your diet!

Mark Allen


Mark Allen is the six-time winner of the Ironman World Championship in Hawaii. He uses these incredible stories of his journey to the top of the toughest one-day sporting event in the world as the backdrop for speeches he gives to companies worldwide. For further information about Mark's speaking availability, please call 1-800-994-5306.

Based in Santa Cruz, California, Mark has a state of the art online triathlon training program at  On this site you can receive fully customized training programs that last twelve to twenty weeks. Each training schedule is based on your fitness history, age and racing goals.

In addition to the online program, Mark co-teaches a workshop titled Fit Body Fit Soul with Brant Secunda who is a shaman, healer, and ceremonial leader in the Huichol Indian tradition. In this unique workshop the themes of Sport and Spirit are explored and integrated together to give people a blueprint for fitness on all levels and for the healing of body, heart, and spirit.

For more information on the next Fit Body Fit Soul seminar please call:
The Dance of the Deer Foundation
or go to


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date: September 4, 2004

1989-1995 Ironman Champion, Mark runs, a online triathlon training system for athletes.

1989-1995 Ironman Champion, Mark runs, a online triathlon training system for athletes. 

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