下载掌阅APP，畅读海量书库
立即打开
DNA testing won't guide dieters to the weight-loss regimen most likely to work for them, scientists reported on Tuesday. The most rigorous study so far found no difference in weight loss between overweight people on diets that “matched” their genotype and those on diets that didn't.
The results underline “how, for most people, knowing genetic risk information doesn't have a big impact,” said Timothy Caulfield, of the University of Alberta, a critic of quackery. “We know weight loss is tough and sustained weight loss is even tougher. Genetics are relevant…but it seems highly unlikely that providing genetic risk information is going to be the magical formula that is going to fix this complex problem.”
The study randomly assigned 609 overweight adults, aged 18 to 50, to either a healthy low-fat or healthy low-carb diet. The volunteers got 22-hour-long classes with dietitians on healthy low-fat diets or low-carb ones, as well as on the dangers of eating mindlessly. Both groups were instructed to eat lots of vegetables and very few foods with added sugars, trans fats, or refined flour. There was virtually no difference in weight loss between the two groups after 12 months: 11.7 pounds in the low-fat group and 13.2 in the low-carb one, a difference that was not statistically significant or meaningful in real life.
The researchers then analyzed weight loss among people whose DNA “matched” or clashed with their assigned diet. That was based on which variants of three genes—called PPARG, ADRB2, and FABP2, which are involved in processes such as fat and carbohydrate metabolism—they had. Earlier research suggested that these variants could predict who would successfully lose weight on which kind of diet.
Of the 244 people with the low-fat genotype, 130 happened to land in the low-fat diet group, meaning they were on the “right” diet for their DNA. That was the case for 97 of the 180 people with the low-carb genotype. The others were mismatched.
“There was no significant difference in weight change among participants matched vs mismatched to their diet assignment,” the researchers wrote. There was also no DNA/diet interaction for waist circumference, body mass index, or body fat percentage.
6. According to the first paragraph, overweight people with diet matched to their DNA ______.
[A] succeed in losing more weight
[B] fail to achieve any weight loss
[C] have tried many types of diets
[D] show no signs of better effect
7. Why the low-carb diets and low-fat ones are mentioned in Paragraph 3?
[A] To prove that the low-carb diet is more effective in weight loss.
[B] To demonstrate the dangers of unhealthy eating habits.
[C] To verify the causal relationship between genotype and diet.
[D] To show that genetics is overestimated as a fix to overweight.
8. According to Paragraph 4, variants of PPARG, ADRB2, and FABP2 were previously used to ______.
[A] estimate whether a diet could work for certain people
[B] predict fat and carbohydrate metabolism in weight loss
[C] provide a successful solution to weight loss
[D] function as an honest indicator of people's weight
9. It can be inferred from the last two paragraphs that ______.
[A] 97 of the 180 with the low-carb genotype were on the mismatched diet
[B] DNA/diet interaction could be found in many body indices
[C] participants with matched diet lost similar weight to those without
[D] the low-carb group came up with different results from the low-fat one
10. Which of the following is the best title for the text?
[A] Matching DNA to a Diet Does Not Work
[B] Overweight Adults Try to Lose Weight
[C] Low-Fat and Low-Carb Diet Take Effect
[D] Variants of Three Genes Call for Attention