Background and Aim
There are few long-term trials comparing intermittent energy restriction (IER) to continuous energy restriction (CER) for weight loss. We compared the effects of CER to two forms of IER; a week-on-week-off energy restriction and a 5:2 program on weight loss, body composition, blood lipids and glucose.
Subjects and Methods
In a one-year randomised parallel trial 332 overweight and obese adults, 18 - 72 years, who were randomised to 1 of 3 groups: CER (4200 kJ/day for women and 5040 kJ/day for men), week-on-week-off energy restriction (alternating between the same energy restriction as the continuous group for one week and one week of habitual diet), or 5:2 (2100 kJ/day on modified fast days each week for women and 2520 kJ/day for men, the 2 days of energy restriction could be consecutive or non-consecutive). Primary outcome was weight loss, and secondary outcomes were changes in body composition, blood lipids and glucose.
Results
146 individuals completed the study (124 female, 22 male, mean BMI 33 kg/m2), weight loss, and body fat loss at 12 months was similar in the three intervention groups, -6.6kg for CER, -5.1kg for the week-on, week-off and -5.0kg for 5:2 (p=0.2 time by diet). Attrition rates were not different (p=0.4). HDL-cholesterol rose (7%) and triglycerides decreased (13%) at 12 months with no differences between groups. No changes were seen for fasting glucose or LDL-cholesterol.
Conclusion
We conclude that the two forms of IER were not statistically different for weight loss, body composition and cardio-metabolic risk factors compared to CER.