A letter has been published in the New England Journal of Medicine giving a follow up to a study comparing low carb, low fat and Mediterranean diets, first published after two years, now after an additional four years.
The results suggest participants on a low carb diet, who had lost most weight after two years, had put a proportion of this back on after six years but still showed significant weight loss overall – but not as much as those on the Mediterranean diet. The low carb and Mediterranean dieters also showed significant improvement in key health markers such as triglycerides, cholesterol and the ratio of HDL to LDL cholesterol. Participants on the low fat diet showed the least benefit in terms of both weight loss and health markers. This is from the New England Journal of Medicine…
For the entire 6-year period, the total weight loss was 0.6 kg in the low-fat group, 3.1 kg in the Mediterranean group, and 1.7 kg in the low-carbohydrate group (P=0.01 for all comparisons) (Figure 1A FIGURE 1Changes from Baseline in Diet-Related Measures.). There was a significant difference in total weight loss between the low-fat group and the Mediterranean group (P=0.01) but not between the low-fat group and the low-carbohydrate group (P=0.44) or between the Mediterranean group and the low-carbohydrate group (P=0.22). Overall, as compared with the weight at baseline, the 6-year weight loss was significant for the Mediterranean group (P<0.001) and the low-carbohydrate group (P=0.02) but not for the low-fat group (P=0.28).
At 6 years, changes from baseline in the ratio of low-density lipoprotein cholesterol to high-density lipoprotein cholesterol were similar in the three groups (P=0.62 for all comparisons), although the change in the ratio was significant in the low-carbohydrate group (a reduction of 0.16, P=0.04) (Figure 1B). Reductions in triglyceride levels from baseline were significant in the Mediterranean group (21.4 mg per deciliter [0.24 mmol per liter], P=0.03) and the low-carbohydrate group (11.3 mg per deciliter (0.13 mmol per liter], P=0.02), with no significant difference among the three groups (P=0.12) (Figure 1C). Overall, there were persistent and significant reductions from baseline in total cholesterol levels in all three study groups, with reductions of 7.4 mg per deciliter (0.19 mmol per liter) in the low-fat group (P=0.03), 13.9 mg per deciliter (0.36 mmol per liter) in the Mediterranean group (P=0.001), and 10.4 mg per deciliter (0.27 mmol per liter) in the low-carbohydrate group (P=0.02; P=0.71 for all comparisons) (Figure 1D).
In conclusion, a 2-year workplace intervention trial involving healthy dietary changes had long-lasting, favorable postintervention effects, particularly among participants receiving the Mediterranean and low-carbohydrate diets, despite a partial regain of weight.