Intermittent fasting (IF) involves alternating between periods of eating and fasting. Many experts praise IF for its potential benefits, including improved weight management, body composition, better overall health, and even increased longevity. But does science truly support its role in extending lifespan?
Dr. Layne Norton recently addressed this topic, sharing his research-based insights. On Nov. 27, 2024, Norton reviewed a study exploring the benefits of intermittent fasting and how it compares to traditional calorie restriction.
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Different Calorie Restriction Types
Dr. Norton highlighted a study examining calorie restriction and various forms of IF, including several different fasting methods:
- Alternate Day Fasting
- 16:8 Intermittent Fasting
- 5:2 Diet
- OMAD Diet (One Meal A Day)
The study compared the effects of intermittent fasting and regular calorie restriction on various health indicators, including cardiometabolic markers, neuroprotective markers (linked to neurodegenerative diseases), and other markers associated with longevity. (1)
Researchers found IF effectively protects these markers and promotes weight loss, improving longevity. Similarly, regular calorie restriction achieves comparable results. According to Dr. Norton, the studies reveal that neither approach outperforms the other, as both rely on the exact underlying mechanisms:
“Excess body fat is anti-longevity regardless of what some extremists in the healthy at every size movement will say,” said Dr. Norton. Obesity is a significant, independent risk factor for mortality, cardiovascular disease, and cancer.
Smoking is one of the most impactful drivers behind serious conditions such as type 2 diabetes, metabolic dysfunction, cardiovascular diseases, and cancer.
When comparing intermittent fasting to traditional calorie restriction in studies where calorie intake is matched, there’s no notable difference in outcomes related to metabolic health, cardiometabolic risk factors, or neuroprotective markers. While intermittent fasting can be an effective tool, traditional calorie restriction — Dr. Norton’s personal preference — is as valid and effective.
Calorie Restriction and Longevity
Dr. Norton cites research suggesting that, for most people who are overweight or obese, reducing food intake and achieving a healthy body weight can significantly enhance longevity.
It’s actually not extending longevity; it’s just getting you the longevity you would have gotten if you hadn’t gained excess body fat.
—Dr. Layne Norton
Numerous studies highlight the link between calorie restriction and improved longevity, though similar benefits have yet to be conclusively demonstrated for intermittent fasting. Research on rhesus monkeys revealed that a 30% reduction in calorie intake led to a measurable lifespan extension.
What these calorie-restriction diets are doing is preventing these animals from becoming obese, and that is why, likely, they are living longer.
—Dr. Layne Norton
If one already maintains a healthy body weight, there’s no need to restrict one’s calorie intake. A healthy weight is inherently better for metabolic health than being overweight, which often requires some calorie restriction, such as intermittent fasting or a specific diet. The key to longevity is choosing a sustainable plan that supports consistency and helps one reach and maintain a healthy weight range.
Regular exercise, particularly resistance training, is as important to health as body weight. Building muscle is crucial since it acts as a “longevity organ,” while excess body fat, which he refers to as a “mortality organ,” poses significant health risks. Excess body fat reduces insulin sensitivity, further underscoring its negative impact on overall well-being.
More Scientific Proof
Dr. Norton discussed a new study comparing intermittent fasting, daily calorie restriction, and intermittent fasting combined with a probiotic. The study, which focused on women with polycystic ovary syndrome (PCOS), found similar results across all approaches in terms of body weight and other health markers. (2)
Key takeaway: when calorie intake is equal, whether through intermittent fasting or regular calorie restriction, the outcomes for body weight, body fat, and health markers are largely the same.
Therefore, choosing the method of calorie restriction that feels the least restrictive and aligns best with one’s lifestyle is critical to losing body fat for increased longevity.
References
- James, D. L., Hawley, N. A., Mohr, A. E., Hermer, J., Ofori, E., Yu, F., & Sears, D. D. (2024). Impact of Intermittent Fasting and/or Caloric Restriction on Aging-Related Outcomes in Adults: A Scoping Review of Randomized Controlled Trials. Nutrients, 16(2), 316. https://doi.org/10.3390/nu16020316
- Talebi, S., Shab-Bidar, S., Moini, A., Mohammadi, H., & Djafarian, K. (2024). The effects of time-restricted eating alone or in combination with probiotic supplementation compared to a calorie-restricted diet on endocrine and metabolic profiles in women with polycystic ovary syndrome: A randomized clinical trial. Diabetes, obesity & metabolism, 26(10), 4468–4479. https://doi.org/10.1111/dom.15801
Featured image via Shutterstock/Raimunda-losantos
