Converting from a glucose to a ketone metabolism is simple, in principle but may be fiendishly complex in application. Time, expense and availability are big factors operationally, and the way people look at you when they find out what you're doing is another. There are others:

Changing over to a ketone metabolism is a major exercise for your body and at first you will feel wrong, because your body will have to retool all its facilities. The faster you change over, the more pronounced these changes will seem to be. Changing over more slowly may mitigate these effects, but I couldn't tell you. I've always gone cold turkey. Some of the differences to be aware of are:

Hyperactive intestines - one of the things insulin does is depress intestinal motility. That means your intestines will be used to be being constantly held back from their fully vivacious and energetic activity. They have to work "harder" to get make things happen when there is a lot of insulin. Once that brake is removed, your intestines will take off like a NASCAR that's been warming its tires at the beginning of a race. This is the worst case, and if you have IBS it could be a problem.

To reduce this tendency, try cutting down on carbs gradually rather than all at once. If you do get the trots, your body will calm down and adjust to the changing chemical and physical demands upon it, given a little time. Maybe two or three weeks. Induction plans are useful for giving folks a reason to stay low carb by showing off immediate weight loss, but they are not necessary. As long as you get your carb intake below what your body needs are, and get enough protein to generate the needful glucose, your body will adjust and you will lose weight. If you take a month to do that but don't suffer from digestive consequence, then maybe it's worth it to accept the slower results. It is likely that our pre-agricultural predecessors got no more than 50-60 grams of carb per day, and they thrived at that level. There's no need to go down to 20 if you pay for it in the loo all day.

Feeling funny or lethargic. While your body is changing over it just won't be as efficient as you are used to. This does not mean the new diet is bad for you. It's just different. Once your body has adjusted (and this could vary greatly from person to person) you should find you feel just as well as before, in many cases much better. If you are an athlete, try to change your diet when you are not expected to compete for a while.

Sugar Cravings. Your body knows very well that something is different, and doesn't like it. You may find you want sweets, because your body liked things the way they were. Bodies resist change. Try an Atkins caramel chew or something, or just tough it out. If you eat actual sugar, abstainingg from any more will be much more difficult.

Water. Drink lots. If you are using ketostix you will notice that the more water you drink the less purple the sticks get, that's becuase they measure mg/dl - and the more pee you build up the more dl there is per mg - dilution. Don't worry about it, it's better to drink more than you need to than less. Caveat: If your stix don't get dark that doesn't mean you're not losing, because they measure only the excreted, extra ketones. Your body might still be burning fat but it's not wasting a lot of it (efficient!) into your urine. If you're keeping the carbs low then the body will use your fat or dietary fat for the energy, this is why you shouldn't eat too MUCH fat - because then it will just burn what you eat and leave the rest on your butt. Eat enough protein and fat to suppress your hunger and stop there.

Mood changes. These are not bad, usually, just be aware. Another effect of insulin is a depressant one. Depressed people who go low carb often find they have to reduce or eliminate their anti-depressants. Talk with your doctor about this, though, don't just flush all your prozac.* It's bad for the fish.

Blood pressure changes. This CAN be dangerous, if you are on medication to reduce blood pressure, be very careful and get a meter. Low carb diets usually reduce blood pressure, and if you are taking medication to lower blood pressure you might wind up with dangerously low BP. Again, do not flush your drugs, they are also very bad for the fish, but talk to your doctor before you reduce or stop taking any medication.*

Apparent stalls in weight loss. The scale might not move, sometimes for a long time. This can be discouraging and make you feel you're not making progress. That can happen for a few reasons, so don't loose heart. Because one day the scale will "suddenly" drop by about 5 lbs when you haven't changed anything.

This can happen if you started exercising and your muscles have adapted and grown bigger. Muscle is dense and heavy. This is my excuse, because when I'm being careful about my diet (and I'm not always) I am also exercising.

I'll be honest, I'm not up on the other reasons, but I have seen many posts about this on low carb fora, it is mentioned in the low carb books and it happens just about everyone at some point. The more you get close to your goal the more likely it is you'll see an apparent stall. The less you need to lose the more likely it is you'll wind up consciously cutting some calories, but if you're more than 30 lbs from your goal or just starting out, you probably won't need to.

Vivid dreams. When I keep my carbs low I don't need the ketostix to tell me I'm in ketosis, I can tell by my technicolor, super-realistic dreams. If they are bad dreams this can be a problem, but most of the time they aren't bad, just vivid. I have no higher frequency of nightmares than before. It happens once or twice a year.

Changes in hair and skin. My complexion is much clearer when my carbs are low. However, when going super low carb and exercising heavily I sometimes find a bit of a rash in one place on my body. It's either sweat or yeast or maybe both, but it passes. In fact, I haven't had it come back in nearly a year.

For women, changes in menstruation, in the absence of chemical birth control, anyway. A shorter period with less bleeding is not unusual.

Operational Factors

High quality protein and fat sources are not cheap

You will have to cook, like, for real, because this stuff doesn't come in a box.

Restaurant foods may have hidden carbs

Your friends/family may not respect your change of diet, and will badger you about how "dangerous" it is. If they can show you a valid clinical study proving your diet is unsafe, then by all means quit. But otherwise, you have many, many resources to document the safety and efficacy of a low carb diet, many of them linked to these pages.

Snacking becomes An Issue. Most of the stuff, except the peanuts, in your nearby vending machine are not low carb. Even peanuts and other nuts can stall weight loss if you are close enough to being in caloric harmony with your calorie intake and burn. Fortunately, most people on low carb don't feel a need to snack. I will sometimes grab a light snack before my workout if it's been more than three hours since I last ate. But if it's less than two hours before the training, I keep it very light, because Sensei nearly kills us. If you know me, you know what I mean. If you don't, suffice it to say that an hour of intensive Shotokan Karate is just a little strenuous.

Parties will be a problem. Usually there will be cheese or cold-cuts, but there will also be carbo-bombs that will be impossible to resist once you let the first bite pass your lips. Unless you are Super Powers of Resistance Person. Or wait till the end and snag one treat on the way out. Make sure you have no cash, though, or you'll be at the 7-11 buyin' twinkies before you know it.

You may find yourself not eating enough. Really! Low Carb dieters naturally reduce calories which can be a problem if you, like me, don't get hungry and forget to eat. If you do not get enough protein your body will scavenge itself to generate the glucose and you will lose muscle mass. Your metabolism may slow down further.

* Talk to your doctor. Be aware that your doctor might blow a gasket if you tell him or her you've gone low carb, because most doctors are basing their advice on the training they received in medical school. A long long time ago. For a very short time. And wrong. Much of this advice is based on concepts that are at best of questionable value when it comes to diet and nutrition.

But, in working with your doctor some delicacy must be exercised to avoid offending the doctor by questioning his or her competence while maintaining your right as a patient to be involved with your own care and make your own decisions.

If you are otherwise healthy and just want to lose weight, many find that their doctors, if presented with a fait accompli of 10 or 20 lbs of lost weight and improved lipid profiles** will re-think their beliefs on low carb dieting and start paying attention to reputable low carb resources. However, if you elect to tell your doctor first and change the diet later, you may find your doctor so resistant that it is easier and safer to find a new doctor with credentials and experience with low carb diets.

**Lipid Profiles are of questionable value in defining cardiovascular risk, except for the triglyceride value. High triglycerides are strongly correlated with CVD, whereas more than half of all heart attacks occur in people with "normal" HDL/LDL numbers. Either "normal" is too high or the measurements are meaningless. There's a lot of evidence that higher HDL is protective, and that the larger, fluffier LDL particles are harmless. The small, dense ones are very atherogenic, but because of how these lipoproteins (not Cholesterol!) are measured you won't know which you have unless you look at your triglyceride number (high is bad) or pay for a very complicated and expensive test. LDL is a moving target, it's based on a simple calculation that doesn't yield accurate results when triglycerides are very low or very high.

If you are extremely ill already, consider finding a specialized clinic with a good reputation in your disease and in low carb dieting before you change anything.

The links below may be of some assistance:

Why "low carb" isn't always, and gets a bad rap.

Protein Power web site, with blog by Dr. Mike and lots of food porn by Dr. Mary Dan. This is a commercial site where you can buy stuff, if you need it. Or not. Dr. Mike's blog is full of great information, both on the benefits of low carb and on the frustrations the low carb world deals with, both as eaters and as medical professionals.