Low-carb diet
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* Sucrose (table sugar) is broken down into fructose and glucose by sucrase in the gut. | * Sucrose (table sugar) is broken down into fructose and glucose by sucrase in the gut. | ||
* Lactose (milk sugar) is broken down into galactose and glucose by lactase in the gut, unless you're lactose intolerant in which case it isn't broken down or absorbed at all. | * Lactose (milk sugar) is broken down into galactose and glucose by lactase in the gut, unless you're lactose intolerant in which case it isn't broken down or absorbed at all. | ||
| − | * Fructose and glucose are already monosaccharides, and don't need to be broken down. | + | * Fructose and glucose (e.g. honey or [[high fructose corn syrup]]) are already monosaccharides, and don't need to be broken down. |
In fibrous carbohydrate sources, such as whole grains or fruits, most of the carbohydrate is still in the form of starches or sugars; only a small percentage is dietary fiber. A typical apple, for example, contains 13 grams of sugar and 3 grams of fiber, while a cup of whole grain wheat flour contains 72 grams of starch and 15 grams of fiber. | In fibrous carbohydrate sources, such as whole grains or fruits, most of the carbohydrate is still in the form of starches or sugars; only a small percentage is dietary fiber. A typical apple, for example, contains 13 grams of sugar and 3 grams of fiber, while a cup of whole grain wheat flour contains 72 grams of starch and 15 grams of fiber. | ||
Revision as of 22:46, 8 January 2013
| Deliciously edible! |
| Dubious diets |
| Food woo |
The low-carb diet has been popularized in recent years through many fad diets such as Atkins, SugarBusters!, The Zone, South Beach Diet, Protein Power, the paleo diet, Tim Ferriss' slow-carb diet and several others. The variety of low carb diets, and the revisions of existing low/lower carb diets has produced a range of low and lower carb diets that are healthy ways to lose weight. However, there are still a host of woo-related low carb and no-carb fad diets out there.
Contents |
The basic low-carb theory
In theory, foods with a high glycemic index, such as most sugars and refined carbohydrates, cause the body to retain more body fat and cause increased hunger due to fluctuating insulin levels. With some of these diets such as Atkins, an "induction phase" at the beginning of the diet seeks to induce a state of ketosis, tricking the body into consuming its own body fat and shedding water retention by reducing the carbohydrate intake below a certain threshold.
Several of the popular low-carb diets (specifically Atkins) are high in saturated fats and excessive in protein intake, leading to increased risk of several diseases from kidney stones to heart disease. Critics note that the same weight loss could be achieved through other diets which do not involve such an unhealthy intake of saturated fats.
Low-carb diets became popular after sensational stories of rapid weight loss, but the real reason for the weight loss is low-carb diets are so restrictive that most people who try to follow them wind up drastically reducing their caloric intake, especially that consisting of sugary foods. Proponents claim the diets make the subject want to eat less in total, and there is some evidence for this.[1]
History
Low-carb diet plans have been around since at least the 1860s.[2] In 1863, an obese Englishman named William Banting was placed on a zero sugar and starch diet by his doctor, William Harvey. Banting published a tract praising the diet.[3] As with most diets, it eventually fell out of favor with people who found it difficult to stick to the regimen.
The first true public resurgence of the low-carb diet occurred in the 1950s and 60s after a Canadian Air Force physician stationed in the far north reportedly noticed that the local Inuits, who ate high-fat diets consisting mostly of whale blubber, exhibited few of the health problems that the CAF personnel suffered from. When he and others at the base experimented with a high-fat, low-carb diet, they lost weight.[4] This was the inspiration for the 1960 book Air Force Diet.
In 1964, Robert Cameron made the low-carb diet appealing to alcoholics with his book The Drinking Man's Diet. This was basically the Air Force Diet plus low-carb distilled spirits, most notably gin, vodka, rum, brandy, whisky, etc. (Note that although grain alcohol isn't a carbohydrate, that doesn't mean it has no calories.) In 2006, Forbes Magazine tried to reintroduce the Drinking Man's Diet to its readers.[5]
The Atkins Diet
The Atkins Diet is the best known low-carb diet. Started by Robert Atkins, it has been around since the early 1970s and considered quackery by most of the medical community for most of its life. After years as a fringe fad diet, for some reason it took off in popularity from about 1998-2004 and spawned a low-carb diet craze that peaked in 2003-04. Several imitators, most notably South Beach and The Zone, remain popular; others like SugarBusters! (a brief craze in 2001) came and went during this time. The inevitable special product lines of low-carb foods proved to be a boon for bargain shoppers when they were marked down to clearance prices once the fad was over. Ironically, the special product lines branded with the South Beach Diet and The Zone brands are laden with - guess what - sugar (although the Atkins and SugarBusters! product lines, to their credit, were not.) So much for "low carb" - sugar is sugar. Both Coca-Cola and Pepsi even got in on the fad with special "half the carbs" mixes (both now discontinued), which were still nonetheless full of high fructose corn syrup (which is sugar).
The reality of low carb, higher protein diets
There is a two fold reality to truly low carb diets: 1) They work[6] 2) They are dangerous[7][8]
The reality with any "Very high protein"(VHP)[9] or "Very low carbohydrate"(VLC)[10] is that they are helpful for short periods of time, but pushing the body into ketosis for extended periods, or asking the body to process high levels of protein leads to a variety of mild to major conditions, including: increased risk of coronary heart disease; kidney dysfunction, liver dysfunction, bone density loss, arthritis, water retention, kidney stones and bad breath (ketoacidosis causes a fruity smell on the breath due to increased acetone in the body) and body odor[11]. So while it does work, it is something best done under the guidance of a physician or dietician (not a nutritionist) and only for short periods of time.
The other problem with high protein diets is that according to several studies, the weight is more quickly regained than with dieters who followed a moderate reduction in calories over a longer time, presumably do to the fact that the weight was lost under the body's "duress", and not simply because more calories were spent than eaten.
Lower carbs + meat = higher mortality
On 7 September 2010, two cohort studies on L-C diets were published together in the Annals of Internal Medicine (Harvard). The participating subjects were 85,168 women (aged 34 to 59 years at baseline) and 44,548 men (aged 40 to 75 years at baseline) without heart disease, cancer, or diabetes. The women were tracked from 1980 to 2006; the men from 1986 to 2006. The results: Animal-based L-C diets were associated with higher all-cause mortality, while vegetable-based L-C diets were associated with reduced all-cause mortality in general, and cardiovascular mortality in particular.[12] This is an important distinction because ol' Doc Atkins claimed that eating a lot of meat was good for your heart.[13] It should be noted that the fats consumed in an animal-based diet tend to contain a higher percentage of saturated fats than the fats in a vegetable-based diet, which would go a long way toward explaining the differences in cardiovascular mortality risk between such diets.
Incidentally, Dr. Atkins died of a slip-and-fall accident in 2003. At six feet and 258 pounds, he would have been described as obese by the CDC, and his death certificate is listed as such. However, his wife has contended that he only weighed 195 pounds (which is listed on medical records at the time he was admitted to the hospital) and the 60+ pounds of weight gain was attributed to bloating during a 9-day coma. There would be an irony in his weight, were it not under dispute.[14]
Saner alternative
More "moderate" low-carb diets can be very useful. Sometimes, but not always, obesity can worsen due to excess carbohydrates from unhealthy sources like white bread and pasta, desserts, and soda. By eliminating or drastically reducing these things from one's diet, one is essentially cutting carbs, and people have lost 30+ lbs. by doing this alone. Other carbs like whole wheat, fruits, and veggies are very much essential, however, and probably shouldn't get the axe. The key is to not overdo it as deprivation of carbohydrates can induce ketosis.[citation needed]
"Good" or "bad" carbs?
Ultimately, all carbohydrates — other than dietary fiber, which is not digested — enter the blood stream as monosaccharide sugars:
- Starches get broken down into maltose and maltotriose by amylase in the saliva, which in turn are broken down into glucose by maltase in the gut.
- Sucrose (table sugar) is broken down into fructose and glucose by sucrase in the gut.
- Lactose (milk sugar) is broken down into galactose and glucose by lactase in the gut, unless you're lactose intolerant in which case it isn't broken down or absorbed at all.
- Fructose and glucose (e.g. honey or high fructose corn syrup) are already monosaccharides, and don't need to be broken down.
In fibrous carbohydrate sources, such as whole grains or fruits, most of the carbohydrate is still in the form of starches or sugars; only a small percentage is dietary fiber. A typical apple, for example, contains 13 grams of sugar and 3 grams of fiber, while a cup of whole grain wheat flour contains 72 grams of starch and 15 grams of fiber.
A crucial difference between different kinds of carbohydrates is how rapidly they're broken down and absorbed into the blood stream, and how "sharp" a spike in blood sugar one experiences after eating them. The glycemic index is one (popular) attempt to quantify this. The glycemic index of a particular foodstuff is calculated by making test subjects eat an amount of the foodstuff that contains 50 grams of total carbohydrate; the subjects' blood glucose is then measured at regular intervals over the next two hours, and the glycemic index is derived from the size of the response curve. Unfortunately, the glycemic index isn't scaled for a reasonable portion size; measuring the G.I. of carrots, for example, requires the test subject to eat a pound and a half of carrots, and nobody does that except Bugs Bunny.[15] A more sane quantity, called the glycemic load, is scaled for portion size, but glycemic load data are much more difficult to come by than glycemic index data.
External links
See also
Footnotes
- ↑ Anne L. Stock, John Yudkin. "Nutrient Intake of Subjects on Low Carbohydrate Diet Used in Treatment of Obesity." Am J Clin Nutr July 1970 vol. 23 no. 7 948-952.
- ↑ It's possible that low-carb diets were prescribed before the 1860s, when the earliest-known low-carb treatise was published.
- ↑ "A Critique of Low-Carbohydrate Ketogenic Weight Reduction Regimens: A Review of Dr. Atkins' Diet Revolution", AtkinsExposed.org website, reprint of an article from Journal of the American Medical Association 224 (1974):1415, accessed 10 May 2010.
- ↑ But remember, this occurred at an isolated air force base where the personnel's diet could be strictly enforced by the chain of command. It's easy to follow a diet when you have no choice.
- ↑ Farnham, Alan. "The Drinking Man's Diet", Forbes website, unknown date in 2006, accessed 10 May 2010.
- ↑ Effects of a LC diet vs. MC diet in obese men
- ↑ http://www.ncbi.nlm.nih.gov/pubmed/15007396 pub med: long term benefits and risks
- ↑ http://www.hopkinsmedicine.org/diabetes/news/highprotein.html. Johns Hopkins, Dangers of High Protein
- ↑ Diets are classified in medical literature as VHP, HP, MP (moderate) and LP
- ↑ Here too, VHC (Very High Carbohydrate), HC, MC, LC (Low Carb), VLC.
- ↑ http://women.webmd.com/guide/high-protein-low-carbohydrate-diets
- ↑ Fung, Teresa T., et al. Abstract of "Low-Carbohydrate Diets and All-Cause and Cause-Specific Mortality: Two Cohort Studies", Annals of Internal Medicine, 153.5 (2010): 289-98.
- ↑ Ornish, Dean. "Atkin's Diet Increases All-Cause Mortality", Huffington Post, 7 September 2010.
- ↑ Even Snopes isn't sure yet
- ↑ http://www.straightdope.com/columns/read/2326/is-the-glycemic-index-the-new-key-to-healthy-eating