Mediterranean and low-carbohydrate diets have lasting, healthy effects, even with partial weight regain, according to a follow-up study by the Nuclear Research Center and BGU.
The results were published last week in a peer-reviewed letter in the current New England Journal of Medicine (NEJM) as an update to the landmark study, the workplace-based Dietary Intervention Randomized Controlled Trial (DIRECT), a tightly controlled 24-month dietary intervention.
According to Dr. Dan Schwarzfuchs from the Nuclear Research Center in Dimona where the research was conducted, “Our follow up subsequent data shows lasting, positive effects of Mediterranean and low-carbohydrate diets six years later.” “Data from trials comparing the effectiveness of weight-loss diets are frequently limited to the intervention period,” explains Dr. Iris Shai, a researcher at BGU (pictured above). “The results after four years suggests that the lipid profile (lower cholesterol, triglycerides and arteriosclerosis) improved over the long term, regardless of partial regain,” according to Rachel Golan, another BGU researcher.
Overall six-year weight loss was significantly lower from baseline for Mediterranean and low-carbohydrate diets, but not for the low–fat group. In the four-year post-intervention, participants regained nearly 2.7kg. Total weight change for the entire six-year period was approximately -3.1kg for the Mediterranean diet and -1.7kg for the low-carbohydrate diet.
After four years post-intervention, more than two-thirds (67 percent) of the DIRECT participants had continued with their original assigned diet, 11 percent switched to another diet and 22 percent weren’t dieting at all.
The researchers also found that after six years, the HDL/LDL ratio remained significantly lower only in the low-carbohydrate diet. Triglyceride levels remained significantly lower in the Mediterranean and low-carbohydrate diets. Overall, total cholesterol levels remained persistently and significantly lower in all diet groups as compared to baseline (low fat:-7.4mg/dL;p=0.03; Mediterranean:-13.9mg/dL;p=0.001; and low-carbohydrate diet: -10.4mg/dL;p=0.02; p=0.709 between groups).
In the original study, 322 moderately obese subjects were randomly assigned to one of three diets: low-fat, restricted-calorie; Mediterranean, restricted-calorie; or low-carbohydrate, non-restricted-calorie and provided daily colored food labeling per-diet in the workplace cafeteria. The two-year adherence rate was 85 percent. The results suggested beneficial metabolic effects to low-carb and Mediterranean diets. Moreover, the researchers found a significant diet-induced regression in the carotid vessel wall volume across all diet groups and that this change was mainly dependent on diet-induced reduction of blood pressure.
Currently, the researchers are performing a new long-term dietary intervention trial that targets weight loss mechanisms across different dietary strategies, using novel techniques.
This research was supported by the Nuclear Research Center Negev; the Chief Scientist Office of the Israeli Ministry of Health (Project No. 300000-4850); and the Dr. Robert C. and Veronica Atkins Research Foundation in Jenkintown, PA.
