With low carb intake, you get low glycogen levels, so minimal water retention. There is your weight loss. You body, specifically, your central nervous system runs exclusively off of pure glucose. The need for glucose remains, even though you deprive your body of it. So you mess with it, it will mess with you. Welcome to the wonderful world of Ketosis, Atkins made millions off of it. In order to keep you functioning, in a state of carb deprivation, the nervous system will start to run off of ketone bodies (products of incomplete fat oxidation, in other words our body can't break down fat properly because there is no "match" to fire it off completely, remember the comment that has been thrown around this forum before, burn fat in a carb fire, this is why). So these ketones bodies, trick (I'm being basic here) the nervous system into thinking they are glucose molecules, so it continues to "run", but not in the same why. It would be like inflating your tires to 20 psi, instead of 120. Hang around a person in the state of ketosis and you will never attempt to do it. Weightlifters/wrestlers/MMA fighters that are trying to make weight can get to this state if they don't know how to make weight properly.

The next step in trying to get more levels of glucose in the blood, is to get after protein. So say bye bye to your lean muscle mass, and say hello to chronic injuries. If you are looking for looks, go for it. If you are looking for a sustainable healthy, long life, stay away. You'll appreciate your connective tissue in your cardiovascular system when you are in your 70's

Ketosis is not a good thing. It is a state your body needs to get in, in order to fuel the central nervous system since you are actively depriving it of glucose. So yes it breaks down fat, but for neural functions (primarily, it will fuel other aspect). So in the long run, you won't be able to maintain training/fuel performance. Body builders can get away with it, since their "race" is standing and flexing a dehydrated body. Go into a tri, dehydrated and in a state of ketosis and you'll drop like a fly once you go upright after the swim. You'll look fantastic doing it, all ripped and cut as you get carted off to the med tent.

The best way to reduce storage fat, is too be patient and follow that ratio I gave you (for meals outside of your workout window). Part of this, is changing your internal chemistry by how you train. Stressing fat burning zones, causes the body to produce more enzymes to aid in lipolysis, HDL/LDL ratios get altered, etc.
This does take years, especially if genetics is not on your side. You can turn on genes, that have been off, or never turned on before by the way you stress the body, but the ease of how this happens is predetermined.
The more lean muscle you have, the more likely you will set up a desire for it to require more energy form the body, thus it it may tap into stores more. In order to stimulate lean muscle to need energy, it has to be contracted, over and over and over again...... what causes a muscle to contract.... a signal from the nervous system... what does the nervous system work off... sugar (strictly glucose). Carbs need to be present to burn fat, since the carb fires the nerve which fires the muscle, etc, etc... Hence, ketosis will not allow your nervous system to perform properly, thus not allowing your muscles to work properly, thus you can't workout at the right intensity for the proper durations of your plan, and you don't burn enough calories during and post exercise for your body to tap into storage fat during the after burn (post workout,which is when you actually "burn" more calories). The better your after burn, the more likely you will get after storage fat. How do you improve your after burn, by working out. How do you maintain working out, by fueling pre/during/post to maintain effort levels (shift your thought process away from fueling muscle, and instead fuel the nervous system, since that ultimately causes the muscle to move properly and with more intensity and consistency). People walk at the end of marathons/IM's because they failed to fuel their nervous system.

If you want quick gains, take drastic measures, but these gains will be short term. If you want to be a sustainable athlete, that grows, and improves, and changes metabolically over time you have to help yourself to a serving of patience pie, with a side of consistency. It doesn't taste good, it isn't easy but it is the only thing that works, long term.

Dr. Peter Attia is THE MAN when it comes to a working knowledge of ketogenesis. There's a really good video with him here: http://pacificfit.net/items/generation-ucan-sports-drink-mix/

And if you go to http://www.bengreenfieldfitness.com and do search for "Peter Attia" a lot of really good podcasts/articles with him...

I just like to do lots of stuff. Personal enjoyment. In college, I started off playing collegiate tennis, then I switched to playing middle for the men's volleyball team and holeset for the water polo team. Then I switched to bodybuilding. Then I did a triathlon and liked that, so I switched to triathlon. Past year I've been getting back into competitive tennis, and next up I plan on trying to make it to Crossfit Games...I just want to make sure I don't get stuck in a rut sportswise and I enjoy living life to fullest!

This article anecdote may help too:

Let’s say you decide you want to join the growing list of individuals who have decided to limit intake of starches, bread, pasta, sugars, gels, sports drinks, bars and other traditional endurance foods.

Once your training partners, family or other friends learn that you’re eating fewer carbohydrates, you’re probably going to hear several objections, along with some scoffing and raised eyebrows.

And usually, the criticism of a low carbohydrate diet for triathletes falls into three categories of objections or questions. Here is what people are going to say, and what you need to know to respond properly.

Objection #1: Isn’t glucose and carbohydrate necessary for energy during exercise? You’re going to bonk if you don’t eat carbohydrates.

While it is true that your body’s cells can certainly burn glucose from carbohydrate for energy, fat is actually a preferred energy source in nearly every cell of your body, and especially for your mitochondria, which are the energy-creating compounds within most cells. Until extremely high exercise intensities are achieved (which is rarely the case among endurance athletes) or until the body has exhausted all storage carbohydrate by exercising for 2-3 hours continuously, fat is completely useable as an energy source – and even after that point, it only takes relatively small amounts of carbohydrate to continue to tap into the body’s own storage fat. Specifically, natural saturated fats, omega-3 fatty acids, and medium chain triglycerides are extremely dense energy sources that produce very little damaging byproducts from their metabolic use for energy – compared to burning blood glucose for fuel, which can cause a significant amount of free radical damage.

But some specific parts of the body do need glucose on daily basis – such as the brain, the nerves, special proteins called “glycoproteins” (which form important compounds such as mucus), and cells within your immune system, your gastrointestinal tract and the kidneys. However - the maximum daily amount of glucose calories required by these parts of the body is about 500-700 carbohydrate calories, and not the 1500-2500 carbohydrate calories consumed by most endurance athletes!

Objection #2: Isn’t all that fat you’ll be eating as a substitute for carbohydrate dangerous because of high cholesterol, heart disease, and weight gain?

Not only can a high fat, low carbohydrate diet perform better for weight loss compared to a low fat, high carbohydrate diet, but there is no evidence that a high fat derived from healthy, natural fat sources increases risk of heart disease – unless fat consumption is paired with high amounts of fructose and a moderate to high intake of starchy, sugary carbohydrate sources. It is at the point when high fat consumption is combined with high carbohydrate consumption that cholesterol in the bloodstream can become oxidized and lead to risk of heart disease.

As a matter of fact, the whole idea that high cholesterol causes heart disease is a flawed hypothesis, and entire books have been written on it. A very good place to start your journey into learning about the positive and healthy properties of fats would be the website http://www.cholesterol-and-health.com/.

Objection #3: Don’t you need to load with carbohydrate before a race? If you don’t carbo load you’re going to bonk.

Once you begin eating a low carbohydrate diet without cheating and including high carb reload days or meals, your body can, within 2 weeks, become extremely efficient at burning fat – a stark difference from the type of fuel utilization that occurs in the endurance athlete trained to eat a gel every 20 minutes during every single training session, or to constantly have sports drink on the edge of the pool and a bowl of pasta waiting at home to re-fuel after the workout.

This means that once you become “fat adapted” you will need relatively fewer carbohydrates during race week or the day before a race, since your body develops an enhanced ability to conserve storage carbohydrate (glycogen) and also an increased ability to utilize fat as a fuel, both during rest and on race day.

What this also means is that an entire week of traditional carbohydrate loading and high sugar intake will not be necessary before your race, and if your goal is weight loss, health, or longevity, may actually end up doing more harm than good if you repeat this “carb loading” scenario multiple times through a training year.

Since I have personally shifted to a lower carbohydrate intake, I have found that the 85-90% carbohydrate diet I was eating during those last few days leading up to a race is no longer necessary. The only increase in carbohydrate that is necessary during race week is A) a carbohydrate dense breakfast the day before and the morning of the race; and B) avoiding any fasted, carbohydrate depleting sessions in the last few days leading up to the race. Because of the natural reduction in physical activity during a taper, simply maintaining your normal carbohydrate intake would still be considered “carbohydrate loading”, but not in the common tradition of loading, which typically includes 7-10 days of high carbohydrate intake before an event.

For more helpful resources on a healthy race day nutrition plan that falls into the category of “low carbohydrate fueling”, check out this article I wrote after winning Leadman 125 earlier this year: http://www.bengreenfieldfitness.com/2012/09/healthy-race-day-nutrition-p...

For an actual meal plan and more specifics on low carb fueling for endurance, you may also want to check out my Low Carbohydrate Guide For Triathletes at http://www.lowcarbtriathlete.com/lowcarbpackage