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Health Options
Alan Titchenal |
Low-carb diet fad first
showed up in 1860sThe popularity of various weight-loss diets swings like a slow pendulum from one extreme to another. The two major extremes are low-carbohydrate and low-fat. It's clear from a quick scan of foods in any supermarket that low-carb diets are now at the top of the hit parade.
Question: Are low-carbohydrate diets a new phenomenon?
Answer: No. The diet pendulum first swung to the low-carb extreme in the 1860s when William Banting promoted a low-carb diet, claiming he had lost 45 pounds without feeling hungry. Since then, many "new and revolutionary" books have appeared that are slight variations on this original theme.
Q: Is the pendulum beginning to swing away?
A: Based on recent rumblings in scientific literature, low-carb popularity may be waning. A hard-hitting article in a major medical journal, The Lancet, reviewed studies conducted on low-carb vs. low-fat diets. It stated that studies lasting three to six months generally observed greater weight loss on low-carb diets but found no significant difference after 12 months. Apparently, dieters are realizing this since low-carb food sales are declining.
Q: Why does the diet pendulum keep swinging?
A: One reason is that it sells books. Everyone is looking for that breakthrough. Few of us know that something has been popular and died off repeatedly during the past 140 years.
Another reason is that it sells new food products. Many of the low-carb foods have replaced sugar and starch in foods with other sweeteners, such as sorbitol, erythritol and glycerine.
All these substances taste sweet and are converted to the common sugar glucose in the body. Their main claim to diet fame is that they do not raise blood sugar levels like sugar and starch. But what is often overlooked is that they do contain as many calories as sugar and starch.
Q: Where should the diet pendulum stop swinging?
A: The pendulum can swing in three major directions, because there are three main sources of calories in foods -- carbohydrate, fat and protein. If one of these nutrients goes down in a diet, one or both of the others must go up.
A sound diet must meet all basic nutrient needs for long-term health and weight management. Among these three calorie sources, adequate protein is most critical to maintaining a strong body structure that functions well.
Carbohydrates provide an energy source essential for brain function and for moderate- to high-intensity exercise. If a diet has too few carbs, the body breaks down protein and converts it to glucose at a rate too slow for optimal mental and physical performance.
The fat in foods provides essential fatty acids and helps the absorption of fat-soluble nutrients such as vitamins A and E, as well as various beneficial phytochemicals.
The diet pendulum is likely to keep swinging among various proportions of carbs, protein and fat. But maybe, in some far-off time, the pendulum will finally stop at a point of balance and the title of the last diet book will be "Grandma's Secret Diet: A Little of Everything, Not Too Much of Anything, and Move That Body."
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Alan Titchenal, Ph.D., C.N.S. and Joannie Dobbs, Ph.D., C.N.S. are nutritionists in the Department of Human Nutrition, Food and Animal Sciences, College of Tropical Agriculture and Human Resources, UH-Manoa. Dr. Dobbs also works with the University Health Services and prepares the nutritional analyses marked with an asterisk in this section.