Anti-aging therapies: Too good to be true?

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Calorie restriction: Is this anti-aging diet worth a try?

Calorie restriction — Find out whether this so-called anti-aging diet can keep you young.

A diet that has extended the life span of worms, flies and rats is capturing the interest of humans. Believers say the calorie restriction diet, which involves eating less, while still getting enough vitamins and nutrients, makes them healthier. And they hope calorie restriction extends their lives.

But just because a diet works in animals doesn't necessarily mean it will work for people. And even if a limited calorie diet was found to extend your life, would you be willing to stick to it?

Scientists have their doubts about the viability of the calorie restriction diet in a Western culture where overweight and obesity seem to be the norm. Still, calorie restriction research may give doctors clues about the aging process and how its effects may be slowed.

Can calorie restriction extend human lives?

It's not clear that humans can benefit from calorie restriction the way animals have. Some researchers believe calorie restriction diets trigger a survival mechanism in animals with a short life span, such as rodents, that allows them to outlive food shortages. Whether people have this adaptation remains to be seen.

Short trials of calorie restriction diets in people have shown some benefit. People undergoing calorie restriction, whether through a restricted diet only or through a combination of diet and exercise, typically have seen positive changes in their:

  • Blood pressure
  • Blood sugar
  • Body fat percentage
  • Cholesterol levels
  • Heart rate
  • Weight

While these are all healthy changes that may reduce the risk of chronic diseases, such as heart disease, it isn't clear whether these changes translate to a longer life span for humans.

Despite the benefits, researchers have also identified risks of calorie restriction diets, including:

  • Reduced bone density
  • Loss of muscle mass
  • Anemia
  • Memory loss
  • Dizziness
  • Depression

Studies of people who are severely malnourished, such as people with anorexia, show that getting inadequate amounts of vitamins and nutrients can lead to serious complications, such as heart failure and death.

Studies have shown that people with the lowest range body mass index (BMI) scores have a higher risk of death than do those with scores considered normal. These studies aren't perfect — they don't take other important factors into consideration, such as undiagnosed cancer or other serious illnesses that may have caused weight loss. But the results do give reason to be cautious when considering calorie restriction.

Should you try calorie restriction?

Very little is known about the long-term effects of calorie restriction in people who have a healthy weight. If you're interested in trying a calorie restricted diet, discuss this with your doctor. He or she can discuss the possible benefits and risks of a calorie restriction diet. Eating enough vitamins and nutrients can be difficult when you're eating less food, so consulting with a nutritionist may be helpful. He or she can help you determine what types of foods can provide you with the nutrition you need.

Sticking to a calorie restriction diet isn't easy. In some clinical trials, participants had their meals prepared by researchers, attended weekly support groups and had counseling sessions to help them stick to the protocol. Outside of a clinical trial, you don't have that same support, so you may have more trouble sticking to the diet.

You might find it easier to use exercise to help achieve your calorie restriction goals, as some participants have done in clinical trials. Rather than cut their caloric intake by 20 percent, for example, some participants cut their diets by 10 percent and used exercise to make up the difference. For instance, a person who needs 2,000 daily calories to maintain his or her weight might eat 200 fewer calories and exercise enough to burn 200 calories each day.

If you're overweight or obese, calorie restriction may be one strategy you can consider to help you achieve a healthy weight. Discuss this with your doctor.

Last Updated: 05/11/2007
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