Weight outcome after 2 years of a diet that excludes six processed foods: exploratory study of the "1,2,3 diet" in a moderately obese population.

Background: The Paleolithic diet, a diet devoid of food-processing procedure, seems to produce a greater decrease in weight compared to healthy reference diets but its limited food choices make it difficult to implement in our modern times where refined food is dominant.

Objective: To evaluate the effects of a 2-year diet that excludes only six refined foodstuffs implicated in obesity. Professional contact was kept minimal to approximate the approach used by most dieters.

Design: Single-arm, open-label, exploratory study.

Setting: One academic medical center, outpatient setting.

Patients: One hundred and five subjects with a mean age of 50 (SD, 14 years) and mean body mass index of 30.5 kg/m (SD, 4 kg/m). Thirty-nine percent had type 2 diabetes.

Intervention: An ad libitum diet that excludes six refined foodstuffs (margarine, vegetable oils, butter, cream, processed meat, and sugary drinks) called the "1,2,3 diet".

Outcomes: Weight at 2 years was the primary outcome. Secondary outcomes included number of patients who lost more than 5% of initial body weight, glycated hemoglobin (HbA) level, and changes in dietary behavior.

Results: Average weight loss was 4.8 kg (<0.001), representing 5.6% of their initial body weight. Among completers (51%), the average weight loss was 5.5 kg (<0.001), and 56% had a reduction of at least 5% of their initial body weight. Among diabetics, weight loss was similar to nondiabetics, and mean HbA level decreased by 1% (=0.001) without modification in glucose-lowering medications. A higher intake of bread, dairy products, chocolate, and fresh fruits was the typical trend in dietary changes reported by completers.

Conclusion: In this exploratory study, there was a significant long-term weight loss with the "1,2,3 diet" despite minimal professional contact. Given the lack of a control group and high attrition rate, further evaluation of this diet is warranted.