medwireNews: A randomized trial published in Science Translational Medicine demonstrates that the benefits of complete fasting can be obtained from a plant-based, restricted calorie alternative, particularly in people with cardiometabolic risk factors.
The study participants followed a diet that supplied around 4600 kJ (1100 kcal) on the first day and 3000 kJ (720 kcal) on the subsequent 4 days, which the researchers describe as “more practical and safer” than complete fasting. The calorie content came from vegetable-based soups, energy bars and drinks, chip (crisp) snacks, tea, plus a multivitamin, mineral, and essential fatty acid supplement.
When following this diet for three cycles of 5 days per month, 52 study participants experienced benefits similar to those seen with complete fasting. They had a significant reduction in insulin-like growth factor-1 levels, of 21.7 ng/mL compared with an 8.7 ng/mL rise in 48 control participants who continued with their usual dietary patterns, and in systolic and diastolic blood pressure, with reductions of 4.5/3.1 versus 0.7/0.7 mmHg.
There were no significant changes in fasting glucose, C-reactive protein, or in any lipid measure, but participants following the fasting-mimicking diet had significant reductions in bodyweight (2.6 kg) and body mass index (BMI; 0.9 kg/m2), as well as in total body fat and trunk fat.
The researchers note that the calorie intake of participants on the intervention diet should only have been around 10% less than that of those on the control diet, meaning that the benefits seen were unlikely to be caused simply by reduced calorie intake.
After the first phase of the trial, the control participants crossed over to the fasting arm, with similar results.
Post-hoc analyses showed that the effects of the fasting-mimicking diet were greatest in participants who had cardiometabolic risk factors at baseline. Indeed, at-risk participants experienced significant improvements in all measured indices except for high-density lipoprotein cholesterol.
For example, BMI fell by 0.5, 0.7, and 1.4 kg/m2 in participants who were normal-weight, overweight, and obese, respectively, at baseline. And fasting glucose fell by 11.8 mg/dL in those with baseline levels above 99 mg/dL. “[N]otably, this reduction brought glucose in these subjects within the healthy range,” observe Valter Longo (University of Southern California, Los Angeles, USA) and study co-authors.
They note, however, that 25% of the participants dropped out of the trial during the fasting-mimicking phase, compared with 10% during the control phase. Six of the 24 dropouts did so because of nonadherence to or dislike of the diet.
“This indicates that, despite our efforts to reduce the burden of low-calorie/protein diets, adherence to this dietary regimen requires committed study participants,” concludes the team.
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