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Online Extra: Low Carbs, High Risks


In the 1970s, Dr. Robert Atkins introduced the Atkins Diet to the public: 30 years later, it's one of America's most popular. Although Atkins devotees swear by their carbohydrate-free life, is the diet really safe? On June 22, 2004, the Partnership for Essential Nutrition, founded by Shape Up America!, was launched with the goal of explaining the health risks associated with low-carb diets. BusinessWeek's Sarah R. Shapiro recently discussed this issue with the President and CEO of Shape Up America!, Barbara Moore. Following are edited excerpts from their conversation:

Q: What was former Surgeon General C. Everett Koop's motivation for starting Shape Up America?

A: He was a good friend and colleague of J. Michael McGinnis and William H. Foege, who published a study in 1993 that created a huge stir. The study is an analysis of death in the U.S. and looks at the actual causes of death, rather than what's exactly written on the death certificate.

They determined that a certain proportion of deaths were preventable because they were due to alcohol, smoking, or poor diet and inactivity. The study concluded that the No. 1 cause of preventable death in America was still tobacco usage, but close behind tobacco usage was poor diet and inactivity. The study said that about 300,000 deaths were attributed to poor diet and inactivity. It has been predicted that in the next 10 years, poor diet and inactivity will be the leading cause of preventable death in the U.S.

That study is what made Dr. Koop found Shape Up America in 1993. I joined in 1995. And the mission of this organization is to raise awareness that obesity is not a cosmetic issue -- it's a health issue -- and to provide responsible information on weight management in an area where there's so much fraud. That's our goal: to try to be the voice of reason in this sea of disinformation that's out there on weight loss.

Q: Low-carb diets have become very popular recently.

A: They were very popular in the '70s when Atkins came out with his first book, and a lot of research was undertaken back in the '70s to explain essentially what was going on there. Then it fell into disuse for a couple of years. And then in the late '90s, it became popular again.

Q: Are these low-carb diets healthy?

A: They are not healthful diets, and they are contrary to decades of solid scientific research that shows that we should be eating a low-fat diet. The majority of our calories should be coming from carbohydrates, and we should be eating a moderate protein diet: 15% to 20% of calories from protein, and anywhere from 45% to 65% of calories should be coming from carbohydrates. And fewer than 30% of our calories for sure should be coming from fat.

Low-carbohydrate diets don't conform at all to that balance. And that's the balance that's reflected in the food-guide pyramid and the dietary guidelines that are promulgated by the U.S. Agriculture Dept.

Q: Can you explain the health effects of low-carbohydrate diets?

A: The brain is an organ that requires carbohydrates. The preferred fuel that the brain uses is glucose, which is a carbohydrate. Your brain uses about 130 grams of glucose a day.

Let's say you're on Atkins and you're in the inductive phase that permits you no more than 20g of carbohydrates. Your brain isn't going to get the glucose it needs, so it turns to the storage depots of glucose in the liver and in the muscle where you have about 24-48 hours worth of stored glucose.

When that [glucose] runs out, you start to feel a little lightheaded, fatigued, confused, and maybe even a little nauseated because your brain is now more desperate for glucose. It starts breaking down body protein. Muscle protein, including heart protein, becomes a target for your body to convert to glucose.

Your kidneys are involved in the breakdown of ammonia [from the muscle proteins]. If you have compromised kidney function and you're on one of these high-protein, low-carbohydrate diets, you're asking a lot of your kidneys. All of the glucose in the liver and the muscle is packed away with water. When you mobilize it, the water gets released and excreted by the kidney. So out comes all this water [which causes you to] lose lots of weight - it can be as much as four pounds in that first early period.

There were studies done in 1976 that were published in the Journal of Clinical Investigation that showed that if you have two diets and they're identical in calories -- one was balanced and one was low-carb -- then the weight loss on the low-carb diet was greater. And the reason it was greater was because of that water loss that I just explained. The fat loss on the two diets is exactly the same. The fat loss has nothing to do with the fact that it's low in carbohydrates.

The human body obeys the basic laws of thermodynamics: What dictates the fat loss is the calories. It's true that this water loss is a metabolic phenomenon, and that's weight loss too. But our goal is not to dehydrate you, but to help you decrease your fat content. You can play metabolic tricks, but if you play those tricks there's a danger involved.

Q: Are there any long-term problems with these low-carb diets? Can you cause yourself any harm?

A: Because of all of the protein, you're increasing the acid load in your body. A high acid level will tend to leach calcium from bone. For the first three decades of life, women are putting down bone and increasing bone density. I worry that if women in their 20s and 30s are using these diets, the diets are interfering with their deposition of bone. Over the long run, these women would increase their risk of fractures and osteoporosis. In order to demonstrate that, you would need to do a study that would have to be a very long duration.

Back in the mid-'90s, the Center for Disease Control became concerned by the number of neural-tube defects in babies born in America. They were arguing that the foliate intake of women in childbearing years was inadequate. To combat this, the CDC decided to fortify cereal and bread products with foliate with the purpose of decreasing the incidence of neural-tube birth defects.

Well guess what foods are targeted by these low-carbohydrate diets? The cereals and the bread groups. I'm very concerned that the low-carb diet craze is going to result in an increase in the neural-tube defects because it's going to undermine the strategy of fortifying breads and cereals.

The government has an expansive cancer-prevention program designed to encourage fruit and vegetable consumption. In any study that included a fruit and vegetable control group, that group did the best and had the lowest incidence of tumors. In our research that we did recently with the Partnership for Essential Nutrition, many of the low-carb dieters reported eating no fruit at all. And even when that diet is liberalized, even when the induction phase is over, they don't go back to a normal intake of carbohydrates. They are well below the 130g that the brain requires according to the Institute of Medicine.

Q: How do the Atkins people and the other low-carb diet camps respond to these types of critiques?

A: They have put out a press release that essentially argues that their critics are somehow funded by the food industry -- especially the part of the food industry that has suffered financial setbacks from the low-carb diets. [But that isn't the case.] Our grant came from Weight Watchers and was for $25,000, which wasn't a great deal of money.

Q: What type of diet would you recommend to someone?

A: I would design a diet that's consistent with the food-pyramid guidelines in the dietary guidelines, and that's what we have done. Shape Up America has a program called Shape Up & Drop 10, which is on our Web site (www.shapeup.org). We try to explain to people that any diet that cuts out an entire food group like carbohydrates or protein or fat is unwise and unhealthy.

We try to give people the understanding that they need so they can choose foods more wisely and learn how to control portions and learn about the importance of physical activity in energy balance and how to lead a more physically active lifestyle.


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