In “Does new study show that all diets are the same?” (on Dr. Sears.com), Dr. Sears says:
If you look at the all the data, there appeared to be no change in long-term weight loss among any of these diets. Upon closer inspection; however, there was a tremendous regression to the mean. This means that people on the low-fat diet started eating more fat, and people in the high-protein diet started eating less protein. All of this occurred in spite of intensive personal and group counseling for the two-year period of the study.
At the end of two years, when researchers asked what people were actually eating, it turns out that only 20 percent of the people in the higher-protein groups were still consuming 25 percent protein. Those who did were losing a lot more weight than those whose protein intake had dropped to 15 percent (the average protein amount). In fact, these changes had high statistical significance (p < 0.001). Interestingly, the 20 percent of the people in the low-fat, high-carbohydrate group who were consuming the most fat had gained significant weight at the end of two years compared to those who maintained a low-fat content. This result was also statistically significant (p<0.001). These were the only two results that were significant in the whole study and never mentioned by the authors of the article or the media (the data can be found in Figure 4 of the article).
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