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It is true that we are all more alike than we are different. But just how useful is that fact when we are in fact dealing with a subject on which many of us ARE different?

Men and women are much more alike than they are different. But as Spencer Tracy says at the end of Adam's Rib, "Hurrah for that little difference!" One does not focus on the similarities between men and women when trying to cure gynecological disorders; there are also differences in everything from heart disease to how we metabolize alcohol.

Generalizations are only useful to a certain point. No human can derive any energy from eating rocks. We need to eat food instead. There are essential fatty acids and essential amino acids that we all need to get from the diet. We all need vitamins and minerals. We need to get energy from our diet. Beyond those very simple and obvious facts, how much usefulness is there in emphasizing how similar everyone is - when we all have different genetics, different tastes, different foods available to us at different times, different lifestyles, different pre-existing conditions, and different attitudes and beliefs about food?

When a doctor is considering what medication to give two different patients suffering from the same disease, he has to take a lot of individual differences in the patients into account, not just blindly prescribe the same medicine to everyone. Even if the disease is the same, the patients are all different.

Food has a profounder influence on the body than any medicine. Shouldn't we take individual differences as seriously in the area of nutrition as we do in the area of pharmacology?

"Calories in, calories out" is a concept with a certain amount of usefulness, but that usefulness is limited. It's an overly mechanistic model, as if we were cars that get a certain predictable number of miles per gallon. But in fact that model doesn't even work on cars, because we all know that different models of cars get different mileage, and the same car might get different mileage according to the driving conditions, how much air is in the tires, how much gunk is in the engine, how much wear and tear the engine has sustained in the past.

I believe it's pretty clearly established that there are genetic differences with regard to the production and utilization of insulin. And it's not surprising that the people who tend to over-produce insulin in the face of certain diets, and who therefore tend to store more fat and become progressively more insulin resistant, appear to make up a large portion of the population. It makes sense that this should be so, because the ability to easily store fat when there is an abundance of food, particularly carbohydrate food, is a useful trait when food availability is uncertain.

Some populations, like the Pima Indians, who apparently passed through a narrow genetic bottleneck at one point in their past, have this trait very strongly. These people have the highest rate of Type II diabetes of any known population in the world. Their genetic tendency is compounded by a generally poor diet and low levels of physical activity. What we see so vividly in the Pima Indians is also illustrated in many other groups, and expresses itself most fully in an age when the diet typically contains high levels of refined carbohydrates and sugars, and when physical activity is low.

Nobody does really well under those conditions; but some people, due to their genetics, do a lot worse than others.

When it comes to specific (non-pharmacological) interventions to treat the problem of insulin resistance, there are three basic strategies. Reduce caloric intake overall, increase physical activity, and reduce carbohydrate intake, most especially refined and starchy carbohydrates, which are nutritionally speaking not very valuable and which have a disproportionate effect on the blood sugar.

Do we have to choose just one of these strategies? Of course not. We can employ all three. If we use just one, we might get some good results, but there are definitely going to be difficulties in the way. If we only increase physical activity and don't do anything about the diet, we put ourselves in a situation where the amount of physical activity needed to overcome the effects of the diet is potentially huge, and not practical for most patients. Remember, we are trying to think about real people here, not mechanistic abstractions.

If we only decrease caloric intake, we run into a pretty serious real-world problem, which is hunger. All that body fat really wants to maintain itself as long as possible, and a high insulin level will help keep it right where it is, while sending the blood sugar into deep dips that drive disproportionate levels of hunger. The current (and already widely questioned) orthodoxy of reducing fat intake while replacing it with carbohydrate tends to rather seriously backfire in this respect, making the hunger problem ever worse. Reducing fat in the diet often has the unintended side effect of reducing protein, and lowering both protein and fat in the diet while increasing carbohydate makes the hunger problem worse, and doesn't really address the insulin problem unless you bring the total caloric intake down to a ridiculously low level. The long-term success rates of extremely calorie-restricted diets have not been good.

There remains this idea of carbohydrate restriction, which makes caloric restriction more possible by better controlling hunger, and ensuring adequate intakes of protein and fat. Those diets that are very restrictive of carbohydrates are called 'ketogenic' diets because they produce a measurable levels of ketones and tend to rely upon protein intake for the small amount of glucose that is still needed by certain tissues (I am sure you are aware that protein can be converted to glucose when it is needed.)

I realize that it is difficult for many people to accept the idea of carbohydrate restriction as a dietary strategy. There are a lot of old prejudices and a great deal of misinformation that needs to be overcome first. For instance, many people assume that because ketones are found in dangerous conditions like starvation and diabetic ketoacidosis, that ketones are therefore dangerous in and of themselves. This is a leap of logic, not actually supported by any evidence. Not all restricted-carbohydrate diets are ketogenic, of course, but those that are tend to be tainted by these prejudices.

Nevertheless, since we are dealing with the real world and a very real public health emergency, I think we need to be very careful about what we reject out-of-hand from our toolkit of strategies. Even with all the combined forces of the pharma industry working on the problem, because Lord knows there's lots of money to be made, we have yet to come up with a really effective anti-obesity drug that does not produce unacceptable side effects. We all know that 'eat less and exercise more' is an easy thing to say, but constant repetition of this fact does not go very far in solving this major social and medical problem.

We need, above all else, a dietary strategy that is not physically painful to adhere to, and which can be easily adapted for long-term maintenance of weight loss. Both of these criteria can be met by low-carbohydrate diets, which are NOT best understood as an irresponsible quick fix.

No one is claiming that low-carbohydrate diets make calories totally irrelevant or that they make exercise unnecessary. But as I believe I explained in previous posts of mine that were linked by InParadise, low-carbohydrate diets can and often do make identical calorie intakes MORE effective for losing weight. This is due, as far as we know, to a combination of factors: the fact that gluconeogenesis is a process of several steps and thus is 'lossy' of energy (I borrow the term from data compression), the fact that lower insulin levels mean excess calories are less efficiently stored as fat, and the fact that higher protein levels tend to increase the resting metabolic rate as well as supporting muscle mass better (which also in turn affects the overall metabolic rate.)

I don't believe that low-carbohydrate diets are right for everyone, but they have enormous potential usefulness, especially among people with a certain genetic profile with regard to hyperinsulinemia and insulin resistance. More and more researchers and clinicians are taking them very seriously these days, and you should too.

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