Aug 25 2009

Low-Carb Diets and Heart Disease

Eat a balanced diet, containing foods from all the good groups, especially fruits and vegetables.

There – for the vast majority of people that is all the diet advice that you need for overall health. Get regular exercise, don’t smoke, maintain a healthy weight, and have good sleep habits – now we have covered most lifestyle risk factors. If people followed this basic advice they would significantly reduce their risk of the most common diseases and disorders.

Often, however, I meet or hear people who add unneeded complexity to what it means to have a healthy lifestyle, even while simultaneously ignoring more basic advice. I can’t tell you how many patients I have who spend hundreds of dollars a month on useless supplements while they still smoke.

The media, weight-loss, and supplement industries are no help. They offer a constant barrage of complex, often conflicting, misleading, or downright false health information. Meanwhile, many people have lost sight of the basics.

Dieting for weight loss is the same. Everyone wants to know the secret to maintaining a thinner waistline. Low-carb diets have been all the rage for at least a decade, despite the fact that they don’t work. What does work is calorie control and exercise – eat a balanced diet in moderation and get regular exercise. Not always easy, but at least it is simple. (Again – this is for most people. Certain health conditions do require special diets.)

The major problem with most diet plans is that they are restrictive. They generally focus on good foods vs bad foods and counsel elimination of the “bad” foods from the diet. This makes it more difficult to get a well-balanced diet, and also reduces compliance. Most such plans will produce short-term weight loss from calorie reduction, but long-term failure. Ninety-five percent of people who go on a diet to lose weight will regain all of their short term losses within a year or two.

A recent study also suggests that low-carb diets may increase vascular risk. Researchers fed mice their regular diet, a western diet high in fat, and a low-carb/high protein diet. They found that the high fat diet had a 9% increase in atherosclerosis (clogging of the arteries) while the low carb diet had a 15% increase. Of course, this is an animal study so translation to humans is not clear. And it was a single study and needs replication. Prior studies have shown that low carb diets do not increase cholesterol levels, probably because short-term weight loss offsets any adverse effect from having higher fat content, but this is still not clear. What we need are long term studies in humans. This animal data is preliminary, but suggests that there is a potential problem and further research is warranted, especially given the popularity of low-carb diets.

This study highlights the fact that restrictive diets may have unintended consequences. Humans are omnivores and we are dependent upon a varied diet.

There is a principle in medical research known as the “intention to treat” model. What this means is that two or more treatment strategies are compared based upon as close to real-life experience as possible and the intention to treat with one or the other. Treatment A may be superior to treatment B in a carefully controlled clinical trial, but if in the real world compliance with treatment A is low because it is complex and unpleasant, while treatment B is cheap and simple, B may yield the best statistical outcomes.

With regard to specific patients I often tell my students that you have to make sure you don’t overwhelm them with details and with a complex regimen. Often the more important basics are lost in the complexity of fine-tuning. This is also part of the individualization of medicine – some patients can tolerate more complexity than others. A hectic executive, for example, may not be able to take a middle-of-the-day dose of medication.

What all this means, in my opinion, is that we need more public health education focusing on the basics – those things that are easy for most people to do that will have the biggest health benefit.

In terms of diet – eating a balanced diet in moderation with plenty of fruits and vegetables is what most people need to focus on.

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