Atkins-diet | weight loss
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dimanche 5 octobre 2014 | 14:11

The aim:

Weight loss.

The claim:

You’ll lose up to 15 pounds within two weeks.

The theory:

The body is an engine; carbs are the gas that makes it go. Limiting carbs makes the body turn to an alternative fuel—stored fat. So sugars and “simple starches” like potatoes, white bread, and rice are all but squeezed out; protein and fat like chicken, meat, and eggs are embraced. Fat is burned; pounds come off.

Reducing total carbs isn’t all there is to Atkins. Limiting the carbs you take in at any one time is also in the game plan. A carb-heavy meal floods the blood with glucose, too much for the cells to use or to store in the liver as glycogen. Where does it end up? As fat.

How does the Atkins Diet work?

You go through four “phases,” starting with very few carbs and eating progressively more until you get to your desired weight. Keeping carbs at bay isn’t as simple as saying No to sugar and baked potatoes. You’ll keep acceptable foods lists handy and polish your arithmetic skills. In phase 1, for example, you’re allowed 20 grams a day of “net carbs” (pull out the food list), 12 to 15 of them from “foundation vegetables” (pull out another list) high in fiber. But as for fat, you don’t even have to trim it off your steak.

Will you lose weight?

Atkins and other low-carb diets have been studied longer and harder than most other approaches, and Atkins does appear to be moderately successful, especially in the first couple of weeks. That’s only part of the story, however.

Much of the initial loss is water, say experts, because of the diet’s diuretic effect. That’s true of many other diets, too, and is one of the reasons researchers don’t judge diets based on a few weeks of results. In diet studies, long-term generally starts at two years. Here’s what several key studies had to say about Atkins and other low-carb diets:
  • Over short periods, Atkins results vary. In one study, published in 2006 in the British Medical Journal, Atkins dieters lost an average of 10 pounds in the first four weeks while those on meal-replacement (Slim Fast), caloric-restriction (Weight Watchers), and low-fat (Rosemary Conley’s Eat Yourself Slim book) diets lost 6 to 7 pounds. At the one-month point and thereafter, however, there were no significant differences in weight loss among the groups.
  • A 2007 study that appeared in the Journal of the American Medical Association divided roughly 300 overweight or obese women into groups and assigned them to one of four types of diets: low-carb (Atkins), low-fat (Ornish), low saturated-fat/moderate-carb (LEARN), and roughly equal parts protein, fat, and carb (Zone). At two months, the Atkins dieters had lost an average of about 9½ pounds compared with 5 to 6 pounds for those on the other three diets. At six months, weight loss for the Atkins group averaged about 13 pounds; the other three groups averaged 4½ to 7 pounds. At 12 months, the Atkins group had lost what researchers called a “modest” 10 pounds; the other dieters averaged 3½ to 6 pounds. Drawing firm conclusions from this study is risky, however. The dropout rate in all four groups was significant, and many participants didn’t follow their assigned diet. The Atkins dieters, for example, took in far more carbs than they were supposed to.
  • A third study, published in 2010 in the Annals of Internal Medicine, found no clear advantage either to a low-carb diet based on Atkins or a generic low-fat diet. Both helped participants lose an average of 11 percent of their starting weight at 12 months, but they gained about a third of it back after that. At two years, average loss for both diets was 7 percent of initial body weight. (That’s still not bad—if you’re overweight, losing just 5 to 10 percent of your current weight can help stave off some diseases.) An analysis of five studies that compared low-carb and low-fat diets published in 2006 in the Archives of Internal Medicine concluded similarly—while weight loss was greater at six months for low-carb dieters, by 12 months that difference wasn’t significant.
  • It is still unclear, regardless of claims made for low-carb diets, whether the main reason for weight loss is carb restriction specifically or simply cutting calories. A study published in 2009 in the New England Journal of Medicine found that after two years, participants assigned either to a 35 percent or a 65 percent carb diet lost about the same amount of weight—6 to 7½ pounds on average. In 2003, researchers who analyzed about 100 low-carb studies concluded in the Journal of the American Medical Association that weight loss on those diets was associated mostly with cutting calories and not with cutting carbs.
  • Researchers reviewed 17 different studies that followed a total of 1,141 obese patients on low-carb eating plans, some similar to the Atkins diet. Results were published in 2012 in Obesity. The study shows that low-carb dieters lost an average of nearly 18 pounds over a period of six months to a year. They also saw improvements in their waist circumference.

Does it have cardiovascular benefits?

A few small, short studies suggest Atkins raises HDL cholesterol and lowers blood pressure, reducing the risk of heart attack and stroke. But many of the studies were small and short, and some of the positive findings did not carry enough statistical weight to be trustworthy. And all that fat worries most experts.

Can it prevent or control diabetes?

No good evidence suggests that Atkins accomplishes either.

Prevention: Research into Atkins or other low-carb diets is sparse. Frequent spikes and dips in blood glucose after carb-heavy meals can, according to Atkins literature, lead to insulin resistance, a frequent precursor to Type 2 diabetes where the body doesn’t respond as it should to the hormone. However, diabetes experts emphasize weight gain from excessive caloric intake, regardless of where those calories come from, increases the risk of developing insulin resistance and possibly diabetes. Losing weight and keeping it off, no matter the diet, will almost certainly reduce your risk of developing the chronic disease.
Control: "The New Atkins for a New You" devotes an entire chapter to diabetes management, but cites only five very small studies to support claims that low-carb diets improve blood-sugar control. Diabetes specialists agree that because blood glucose dips and spikes are intimately tied to carb consumption, carefully choosing and restricting some carbs is important. But the 30 or fewer grams a day specified in some Atkins phases is too extreme, concluded the authors of a 2005 report published in Nutrition and Metabolism.
A study published in 2013 in the American Journal of Clinical Nutrition suggests that low-carb diets are as effective as low-GI,Mediterranean and high-protein diets in improving various markers of cardiovascular risk among people with diabetes.
A few recent studies have shown that Atkins or other low-carb approaches help lower blood glucose and insulin levels—suggesting they may stave off diabetes or help diabetics control their condition—but they don’t do it significantly better than other diets.

Are there health risks?

No indications of serious short-term risks have surfaced. Reported side effects are generally minor. They include weakness, nausea, dizziness, constipation, irritability, and bad breath. Atkins hasn’t been studied beyond two years, so long-term risks are uncertain.

Most experts feel that diets high in saturated fat significantly raise the risk of heart disease and cardiovascular events such as heart attack and stroke. The latest Atkins book calls this a “myth,” however, asserting that carb restriction changes the way the body processes fat in the diet.
Keep in mind Atkins isn’t safe for everyone:
  • Pregnant women should go directly to the phase 4 maintenance stage.
  • Adolescents and diabetics on medications to control blood sugar should consult with their doctors.

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