Few things garner as much attention as the latest diet craze. You cant escape it. Internet spam, TV ads, infomercials, news programs, magazines, radio segments, billboards, junk mail, bestsellers, and airplane banners bombard the brain. Unfortunately, historically, this is an endless cycle -- only the media changes. In brief, about every decade or so a new faux scientific diet emerges and is hyped up to such an astounding degree that the only way to miss being blasted by this massive assault would be if you happened to have been assigned prolonged duty at an extremely remote locale such as the bottom of a deep trench in the Pacific ocean. Eventually the new diet, which promises to cure every known human affliction, becomes the old diet that has failed to withstand scientific scrutiny -- or maybe people have just grown tired of hearing about it and want to leap the latest new diet and it just fades away. Repeat cycle.
The current fad involves several different diets that are variations on the same theme, low-carbohydrate. There are several contenders Atkins, the Zone, Sugar Busters, Protein Power and a few others that vary in the severity of the carbohydrate restriction recommended, but the evil carbohydrate concept is the same. Another similarity is the lack of scientific evidence supporting the assertion that these diets are healthy. To understand why so many nutritional experts have significant concerns about these diets it is first necessary to review a few basics about dieting and weight loss.
At the core of most dieting plans is the simple concept that if you spend more calories than you consume you will lose weight. This is because your body must make up the difference in energy by breaking down and utilizing some part of itself, essentially converting matter into energy. This self-cannibalism, or catabolism as it is correctly called, usually starts with breakdown of the biggest fuel depot, stored body fat. Thus any diet in which there is caloric restriction will result in weight loss.
Many overweight people also have a variety of secondary health problems directly related to being overweight. These problems include things like elevated blood pressure, high cholesterol, and insulin resistance. Correspondingly when they lose weight these related health problems get better or go away. Most of the pseudo-scientific arguments given in support of fad diets will point out a whole host of these physiological variables. The fad diet creators and proponents will argue that not only does someone on their diet plan lose weight, but all these bad physiological variables get better too. Therefore, they argue, the fad diet is scientifically valid and is healthy (and is the best thing to ever have been invented and I should get a Nobel prize). You can of course use this argument to prove that eating dirt is healthy. After all the nutrient value of dirt is low when compared to a hunk of meat. Thus one may hypothesize that the Dirt Diet, in which you get to eat all the dirt you want -- of course not just any dirt but our Dirt which we sell in a variety of convenient forms (e.g., Dirt bars, Dirt soufflé, instant tear-open Dirt pouches, etc.) -- for breakfast and lunch followed by a sensible meal at dinner time, will result in weight loss, lower cholesterol, lower blood pressure, etc.
Low-carb diets (LCD), such as the Atkins diet, have a few selling points. There is initial weight loss and they may be easier for people to maintain due to the tasty foods included. However, despite claims to the contrary, the weight loss is due to calorie restriction and to a diuretic effect. There is not some magical transformation of internal biochemical pathways due to the special composition of the foods eaten (approved foods, bars, snacks and cookbooks are now on sale, by the way, at a steep markup). Weight loss due to calorie restriction was covered above. The diuretic (pee your way to a lower body weight) effect of the Atkins diet, for example, occurs because water is used to flush out ketones generated by stored fat catabolism due to reduced calorie intake and because the body trying to get rid of excess amino acids from the high protein intake.
Now that the short-term positives are out of the way we can examine the long-term ramifications of LCDs. Many of these diets accelerate atherosclerosis because they are high in saturated fat and cholesterol. Additionally, because LCDs significantly limit the intake of fresh fruits, whole grains, and vegetables all the well-described preventive health benefits of these foods are lost. For starters, these benefits include reduced risk of cancer and heart disease, and enhanced immune function. These are benefits that should not be chucked out the window just because an unproven fad diet says so. Finally, the high protein load of LCDs may have negative consequences for the liver, kidneys, and bone (osteoporosis). These last have not been conclusively proven but I think that is exactly the point. The other glaring fact for athletes is that there is no better way to completely trash your performance than a low-carb diet.
To their credit LCDs proponents have helped many people understand that too many poor quality carbs (i.e., simple sugars) are not healthy. You will gain a lot of fat if you eat nothing but doughnuts. This of course is not a shocking, new headline. Moms all over the country have for centuries imparted several important dietary lessons to their offspring. Many will recall those anecdotes,
1. Eating nothing but cookies and cake all day is bad for you (i.e., you will get fat and suffer severe consequences)
2. Eat your fruit and vegetables theyre good for you (i.e., this will help prevent disease)
3. Too much junk food is bad for you (i.e., dont sue McDonalds because you were too stupid to follow my advice)
It is astounding that the LCD crowd could just shove all these collective Moms aside. Rather than lump all carbohydrates into the evil bin it would be nice if the LCD folks did not ignore the extensive data on the health benefits of complex carbohydrates. Fresh fruit, whole grains, and vegetables are actually good for you. In fact as our current understanding, derived from legitimate science, grows we are learning that the more fruits and vegetables you eat the better your health. (Does anyone reading this actually believe that eating fruit is unhealthy!?)
Understanding the advancements in nutritional science is similar to watching a screen as pixels are gradually added. It seems slow but as more data is added a picture begins to emerge. Educating oneself about nutrition is thus a gradual and on-going process. Perhaps the best starting place for accurate dietary information is the National Institutes of Health. Check out
Another useful site is for health scams is
As a final note, it is difficult to argue with the economic side of fad diets. LCDs have generated such a massive market share of the multi-billion dollar diet industry pie that science has become irrelevant. Money wins over science. This cynical perspective can only be enhanced when one hears that fast-food establishments are now offering Atkins approved fare. Its all about market share.