Intermittent Fasting—Short- and Long-Term Quality of Life, Fatigue, and Safety in Healthy Volunteers: A Prospective, Clinical Trial

Abstract

Background: Intermittent fasting (IF) is defined as an eating pattern without calorie restrictions, alternating between periods of fasting and eating. In the past decades IF has not only become a popular weight-reducing diet but is thought to improve Quality of Life (QoL) and fatigue. However, very little evidence exists for the general population. Thus, we aimed to assess the impact of a 16-h fasting period per day over a three-month study period on QoL and especially fatigue in healthy people. Methods: We conducted a prospective cohort study including healthy subjects. All participants fasted 16 h for at least five days a week while maintaining their normal lifestyle. In the study, we analysed blood samples as well as QoL through standardized questionnaires (WHO-5 questionnaire, Short Form Health 36). Furthermore, we measured the degree of fatigue with the Fatigue Assessment Scale (FAS) and Fatigue Severity Scale (FSS) as well as compliance, activity records, and weight alterations. All endpoints were evaluated at baseline, after two weeks, four weeks, and three months of IF. Results: A total of 30 participants fasted for the entire study period. The results of the WHO-5 questionnaire (15.6 ± 4.6 vs. 18 ± 3.6, p < 0.0019) demonstrated a significant increase in QoL. For long-term QoL six out of eight domains measured by the Short Form Health 36 (SF-36) significantly improved (e.g., physical health: 92.3 ± 11.6 vs. 96.5 ± 6.3, p = 0.015; mental health: 75.5 ± 12.0 vs. 81.7 ± 9.0; p < 0.001 and body pain: 74.1 ± 31.8 vs. 89.5 ± 14.9; p = 0.008) after three months. Fatigue significantly decreased from 10.3 ± 3.2 to 8.4 ± 2.5; p = 0.002 for mental fatigue and from 12.6 ± 3.8 to 10.7 ± 3.3; p = 0.002 measured by the FAS. The mean FSS-Score at baseline was 3.5 ± 1.2 compared to 2.9 ± 1.1 (scale 1–7) after three months (p < 0.001). Notably, the proliferation marker IGF-1 was significantly reduced. No clinically significant changes in laboratory parameters were observed that would have endangered a participant’s safety. Conclusions: IF according to the 16:8 regime over a fasting period of three months significantly improved several aspects of the QoL and decreased fatigue in healthy people, while maintaining a good safety profile. The practicability of this diet was also demonstrated for shift workers and people with a high percentage of active labour. Apart from the improvement in QoL and fatigue, the significant reduction in IGF-1, which can act as an accelerator of tumour development and progression, might be an indicator of the potential benefits of IF for patients with cancer.

Therapeutic Fasting and Vitamin D Levels: A New Dimension in Type 2 Diabetes Mellitus Prevention and Management—A Brief Report

“…29 Therapeutic fasting is known to improve the quality of life and general well-being. 30 Our inferences indicate that fasting is associated with significant improvements in perceived energy levels, quality of life, and disease perception. This suggests fasting as a potential holistic tool that can be integrated into the management of diabetes.…”

Nutrition Strategies Promoting Healthy Aging: From Improvement of Cardiovascular and Brain Health to Prevention of Age-Associated Diseases

“…Several types of diets have been developed to promote healthy aging [ 27 ]. Intermittent fasting significantly improved several aspects of the quality of life, decreased fatigue and significantly lowered IGF-1, which can act as an accelerator of tumor development and progression [ 27 ].…”

“…Several types of diets have been developed to promote healthy aging [ 27 ]. Intermittent fasting significantly improved several aspects of the quality of life, decreased fatigue and significantly lowered IGF-1, which can act as an accelerator of tumor development and progression [ 27 ]. Longevity-promoting diets include caloric restriction, intermittent fasting (ideally with an 11–12 h daily eating period), restriction of methionine intake, and consumption of fruits and vegetables, legumes, whole grains and oilseeds rich in beneficial fats (e.g., nuts) [ 139 ].…”

“…One of them is an unhealthy diet accompanied by diseases related to a poor diet [ 22 ], such as overweight, obesity [ 23 ] and metabolic syndrome, which may affect up to 75% of the population aged over 60 [ 24 ]. Preclinical studies provide ample evidence that several components of diet, such as protein, carbohydrate and fat content as well as intake of calories, play important roles in regulating aging processes and longevity and development of age-associated diseases, including cardiovascular and cerebrovascular diseases, cognitive impairment and dementia, and malignant diseases [ 19 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 ]. Dietary regimens that favor reduced calorie intake were shown to delay aging and the genesis of age-associated diseases [ 31 , 47 ].…”

Does Timing Matter? A Narrative Review of Intermittent Fasting Variants and Their Effects on Bodyweight and Body Composition

“…Overall, the IF variants included in this review do not appear to pose greater safety risks compared to conventional/linear dieting. Emerging research has shown TRE to improve subjective ratings of quality of life [ 60 , 61 ]. Systematic reviews and meta-analyses consistently report a lack of serious adverse events across studies [ 3 , 62 , 63 ].…”