Introduction to low-carb water diet:
After all these years of reporting on diet and obesity, I am sure of one thing: for different people, the effect of the same recipe is very different, and it is even more nonsense to successfully lose weight with a diet that is difficult to adhere to.
Leviathan press:
Pay attention to attention, first of all, we must distinguish one point, "can the low-carb water diet lose weight" and "can the low-carb water diet maintain weight" are two issues. This is also a point that the experiment in this article repeatedly emphasizes: namely, that a low-carb water diet is effective for maintaining weight.
So the question is, for those who are eager to lose weight, can a low-carb water diet work?
Among the various dietary debates, the most controversial question is probably this: how much does carbohydrate intake affect weight loss?
On the one hand, a legion of respected scientists, New York Times reporter Gary Taubes, and adherents of the Atkins diet, regional dieting, and ketogenic diet are adamant that weight loss will be easy if we can control ourselves away from pasta, bagels and cookies.
On the other hand, equally well-known researchers and nutritionists scoff at claims of a low-carb diet. They say the vast majority of studies show that low-carb diets are no different from other diets in terms of weight maintenance.
Reducing carbohydrate:
This low-carbon water debate is in full swing. On the morning of Nov. 11, Dr. Oz joined the fray, stressing on "Today show" that new research suggests that reducing carbohydrate intake can help "ease weight loss and prevent weight regain."
The study, published in the journal BMJ, was led by researchers at Boston Children's Hospital and is arguably the most rigorous dietary study to date. The study, while not proving that Dr. Oz was completely right, provided important arguments. But it should be added here that in the field of nutrition, it is difficult to prove anything.
Diet was high, medium carb or low carb:
The study, which cost up to $1200 million, wanted to see which diet was high, medium carb or low carb was more effective at preventing weight regain over a 20-week period. But they were most interested in whether total caloric intake or calorie-providing foods were more important for weight control.
Key fact:
Some diet and nutrition experts say that the number of calories you eat is the key, and you can lose weight by reducing your total calorie intake. But some experts believe that how calories are consumed is also crucial.
Refined grains and sugar, can lead to obesity:
The carbohydrate-insulin hypothesis is the main scientific basis for the latter camp, and has been strongly promoted by Taubes, Harvard professor David Ludwig, Robert Lustig of the University of California, San Francisco, and others. This hypothesis suggests that a diet high in carbohydrates, especially refined grains and sugar, can lead to obesity. Because the intake of carbohydrates promotes insulin secretion, leading to fat accumulation and inhibiting calorie burning.
Remedy:
According to this hypothesis, to successfully lose weight and prevent rebound, it is necessary to reduce carbohydrate intake and instead consume calories through fat, thereby reducing insulin levels in the body, promoting calorie consumption, and helping fat burning.
Research and Experiments:
The new study was of the highest quality of all the studies that tested the carbohydrate-insulin hypothesis and in which participants were "free people" (not in hospital rooms or energy metabolism laboratories).
Researchers at Boston Children's Hospital, Harvard Medical School and other universities recruited 234 subjects and first asked them to lose 9 percent of their body weight in 10 to 12 weeks.
The reason why the experiment was designed in this way is that it is known that no matter how you diet, most people can successfully lose weight, and the difficulty is to maintain weight. The researchers wondered if a low-carb diet could help people who lost weight burn more calories and prevent weight regain, as the carbohydrate-insulin model suggested.
Of the 234 subjects, 164 completed the weight loss goal and entered the most important second phase of the experiment.
Final words:
The researchers randomly divided the 164 participants into three groups. Participants in the high-carb, medium-carb, and low-carb diet groups accounted for 60%, 40%, and 20% of the total, respectively. Over the next 20 weeks, their meals and snacks were provided by the researchers. To help participants maintain their weight, the diets of all three groups were carefully designed.
By week 100, the carbohydrate effect is significant: the less carbohydrates you consume, the more calories you burn, and according to this logic, a low-carb diet is more conducive to weight maintenance. Participants in the high-carb group did not consume additional calories, compared with those in the medium-carb and low-carb water groups, which burned 200 and <> more calories per day, respectively.
"This longest-fought and largest dietary experiment to date not only supports the carbohydrate-insulin hypothesis, but also amply demonstrates that calorie metabolism patterns differ from different foods," said Ludwig of Harvard University, one of the study's authors, "These findings suggest that focusing on carbohydrate restriction may be more effective in maintaining weight in the long term than restricting calorie intake."
Words of scientist:
Christopher Gardener, a scientist at Stanford University who was not involved in the study, told me that he believes the study yielded remarkable results through a "simple and ingenious" experimental design: "The study determined whether [a low-carb diet] has benefits or disadvantages for maintaining weight loss in the long term." ”
But Gardner points out that these findings may not yet be applied and popularized.
In most dietary experiments, researchers do not provide subjects with all food. These experiments have shown that there is no difference between the low-carb diet and other diets in terms of weight loss effects. In other words, just ask people who lose weight and will find that dieters who adhere to low-carb diets lose about the same amount of weight as those who eat high-carb diets. But that doesn't overturn the conclusions of the new study. The problem is that unless the researchers prepare the food themselves, they can't guarantee long-term adherence to dieters, regardless of the recipe.
Gardner said: "If the feasibility of a weight loss method is low, even if you can prove that it works, it won't help."”
Experiment demonstration:
The point is that in other control variable experiments that tested the carbohydrate-insulin hypothesis, subjects were in the energy metabolism laboratory, but none of these experiments demonstrated that a low-carb diet significantly promoted calorie burning and weight loss.
But these studies are flawed:
They are largely focused on losing weight, not maintaining it, and don't last as long as the new study. Therefore, the new study may show that dieters can only burn more calories after 10 weeks of sticking to a low-carb diet.
Among the researchers caught up in the low-carb diet debate, others point to another problem with the new study. It's professional, but it's fun, so be patient and keep watching.
Kevin Hall, an obesity researcher at the National Institutes of Health, has studied low-carb diets. He pointed out that this time, both before the experiment and throughout the experiment, the researchers used doubly labeled water to measure caloric expenditure. This method requires subjects to drink water labeled with the stable isotope deuterium and heavy oxygen (oxygen-18). These isotopes are not common in the human body, so by taking a sample of the subject's urine and measuring how quickly they are excreted, the researchers can determine the subject's metabolic rate and thus know how much energy they consume each day.
Hal says that in cases where the subject is a "free man" (not in the energy metabolism lab), the double-standard water method is the industry gold standard for measuring energy consumption. But the problem lies in the way the new study applies the double-standard water method.
Change is necessary:
If the subject has just lost weight successfully, or if the eating habits are changing, the double-standard water method is not so reliable. In the original study proposal, a statement of intent before the experiment began, the researchers said they would measure baseline data using the double-labeled water method before the subjects began to lose weight, after which the subjects' weight would stabilize. "Researchers should have used the double-standard water method at this time," Hal said.
However, due to a mistake, the researchers started the double-standard water method only after the subjects had lost weight, and used the measurements before the randomization as the baseline data. To their credit, they did not hide this in their report.
The researchers published the data before the subjects lost weight, which Hal used to recalculate and report on it at the recent Obesity Week symposium. He found that if the measured results of the subjects before losing weight were used as the baseline data, the effect of the low-carb water diet on calorie consumption was far less significant - compared with the high-carb group, the low-carb water group subjects consumed less than 100 more calories per day, which was not statistically significant.
Conclusion:
Sam Klein is an expert in metabolism and obesity research at Washington University in St. Louis. He said the study, published in the British Medical Journal, was a "masterpiece of science". Klein agrees with Hal's doubts, and agrees that the conclusions of the new study contradict existing knowledge on energy expenditure most likely because of the methodological problems that Hal pointed out. He concluded: "If the data before weight loss is used as a baseline, the effect of a low-carb diet is not so obvious. ”
Ludwig said the criticisms are based on misconceptions, and that the new study focuses on preventing weight regain, and that benchmarking pre-weight loss data conflicts with the purpose of the study and creates other biases.
In an email to Vox News Nov. 11, after the publication of the article, Ludwig said that benchmark data measurements were performed before randomization, so the researchers could not manipulate the results of the experiment to make a certain diet look better using any individual differences, including weight. Ludwig and the study's collaborators also issued a statement in response to Hal's questioning in the British Medical Journal about his choice of baseline data.
Should you stay away from carbohydrates:
"All scientists have the right to ask questions, to reanalyze the data, to question our interpretation of the data," Ludwig adds, "and in order to be as transparent as possible, we have published all the data and statistical methods so that anyone can analyze them."
Let's get back to the most important question: Should you stay away from carbohydrates if you want to prevent weight regain?
If you're confused right now, that's normal. The debate over dieting is getting fiercer, we're getting more critical, and personal biases and vested interests make it hard to decide what to believe. In fact, nutrition research is unlikely to draw seamless conclusions, so it is often criticized for being able to interpret it in different ways and easily criticize it.
My final words of debate:
Aside from this new study, I haven't found any evidence of irresistible benefits of a low-carb diet. However, it may also be that I was blinded by my love of pasta, bread and cake, and my efforts to limit my carbohydrate intake failed, and I was unable to accept a low-carb lifestyle (in fact, I ate more carbohydrates than before during my long-term weight loss time).
After all these years of reporting on diet and obesity, I am sure of one thing: for different people, the effect of the same recipe is very different, and it is even more nonsense to successfully lose weight with a diet that is difficult to adhere to.
Those scientists who are much smarter than me have long said that a weight loss recipe that you can stick to is the best for you. If your weight loss diet happens to be low-carb water, that's great, and if the conclusions of the new study hold up, you may be able to burn more calories. Ludwig and other authors also called on scientists to do more research. Given that the conclusions of the new study contradict the existing evidence base, the reproducibility of the experiment will be crucial.
Either way, Gardner said, "I haven't seen anyone oppose reducing sugar and refined grains, which are an important part of the American diet." It doesn't hurt to eat fewer less nutritious carbohydrates.
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