Researchers compared the effects of two dietary strategies on metabolic markers, cardiovascular disease risk estimates, and blood pressure in obese and overweight adults. Compared to daily calorie restriction, 5:2 intermittent fasting led to modestly greater improvements in systolic blood pressure and pulse pressure, as well as a larger reduction in body mass index-based cardiovascular risk scores, while triglyceride levels declined only within the intermittent fasting group and not significantly more than with calorie restriction.
Study
Using data from the Iranian National Obesity Registry, researchers compared the real-world effects of 5:2 intermittent fasting and daily caloric restriction on cardiovascular risk factors and estimated long-term CVD risk scores in obese and overweight adults.
Adults aged 18 to 65 years with a body mass index (BMI) of at least 25 kg/m² and at least 3 months of follow-up were included. Participants were excluded if they were breastfeeding, using weight loss medications, had conditions affecting metabolism, or did not adhere to their prescribed diet.
Participants were categorized, rather than randomly assigned, into either a 5:2 intermittent fasting regimen or a daily calorie restriction regimen, per routine clinical protocols and clinician guidance. In the intermittent fasting group, women consumed 500 kcal and men 600 kcal for two non-consecutive days each week, with normal energy intake on the remaining days. The calorie restriction group followed a daily diet that provided a 500-1000 kcal energy deficit. Macronutrient composition was similar across groups, and all diets were supervised by trained dietitians.
Findings
Anthropometric measures, blood pressure indices, laboratory markers including glucose and lipid profiles, and physical activity were assessed at baseline and after three months. Long-term cardiovascular risk was estimated using BMI-based and lipid-based 30-year Framingham risk scores, as well as additional atherogenic indices. Statistical analyses compared within-group and between-group changes, adjusting for age, sex, BMI, and baseline values.
Out of 345 individuals initially enrolled, 82 were included in the final analysis, with 40 assigned to the intermittent fasting group and 42 to the calorie restriction group. The average age was about 36 years, and most participants were women. Baseline demographic characteristics, lifestyle factors, and energy intake were similar across measured variables, indicating reasonable balance in observed characteristics, though unmeasured confounding cannot be excluded.
Over 12 weeks, both dietary approaches led to significantly lower rate pressure product, mean arterial pressure, and systolic blood pressure. Systolic blood pressure was considerably lower in the intermittent fasting group after the study compared with the calorie restriction group. Pulse pressure also declined more in the intermittent fasting group. Within this group, diastolic blood pressure and pulse rate decreased significantly, although these latter changes did not differ significantly between groups.
Triglyceride levels fell significantly within the 5:2 intermittent fasting group, but between-group differences were not statistically significant, while total cholesterol, low-density lipoprotein cholesterol (LDL), high-density lipoprotein cholesterol (HDL), fasting glucose, and glycated hemoglobin remained unchanged in both groups. Liver enzymes improved within the intermittent fasting group, with no between-group differences. Kidney function markers showed no changes.
Both groups experienced significant reductions in BMI-based 30-years Framingham cardiovascular risk scores, but these reductions were greater in the intermittent fasting group. Lipid-based risk scores declined within the intermittent fasting group but did not differ significantly between groups. Adjusted analyses confirmed significant between-group differences for pulse pressure, systolic blood pressure, and BMI-based cardiovascular risk.
Conclusion
These findings align with previous studies reporting blood pressure benefits of intermittent fasting, while confirming that short-term interventions may have limited effects on lipid fractions and glycemic markers in largely non-diabetic populations. Observed between-group differences were modest in magnitude, and cardiovascular risk outcomes were based on estimated risk scores rather than clinical events. Potential mechanisms include improved autonomic regulation, reduced inflammation, enhanced fat oxidation, and metabolic switching during fasting periods, although these pathways were not directly measured.
Key strengths include the registry-based design reflecting routine clinical practice, comparable baseline characteristics, and the use of comprehensive cardiovascular risk scores. However, the observational design, short follow-up, modest sample size, missing laboratory data for a substantial proportion of participants, and reliance on self-reported dietary data limit causal inference. Blinding was not possible, making it difficult to account for all confounding factors.
Overall, the findings suggest that intermittent fasting may offer small but potentially meaningful improvements in certain blood pressure measures and estimated cardiovascular risk, particularly in a relatively young, predominantly female population, warranting longer and larger studies to confirm sustainability and clinical impact.
Source:
https://www.news-medical.net/news/20251217/Intermittent-fasting-edges-daily-calorie-cuts-for-blood-pressure-and-long-term-cardiovascular-risk-estimates.aspx