Chrononutrition, Intermittent Fasting, Time Restricted Feeding: My personal experience and what current research explains.

Over a decade ago I began to experiment with time-restricted feeding. Initially it was due to chronic GI and throat issues. For several years for most of the day I felt like something was stuck in my throat and randomly have deep painful pressure in my chest deep to the sternum. For about two years I visited several doctors like ENT’s and GI specialists, even an had and endoscopy and barium swallow with no findings. To treat the symptoms without any definite, understand or diagnosis from any doctor a general recommendation to take PPI’s and use Gaviscon or other antacids as needed.

Obviously, I thought this advice was garbage from both a long-term health solution standpoint, and they fact these doctors never determined the cause of my symptoms. Thus, investigation because to understand the real physiological issues causing these symptoms. First, I started experimented with time restricted eating after reading though research on it for gut and digestive health. I begin to refrain from eating within 3 hours before bed and delay feeding upon awakening the first 2 hours. This was giving me about a 10-hour feeding window. Within a few months all my symptoms had resolved and have had no recurrence in nearly a decade.

No clear research appears to have investigated these types of symptoms of gastroinestinal origin and immplentation of TRF (time restricted feeding) or "chrononutrution" as an isolated intervention. My working hypothesis is somehow chronically eating throughout the day leads to inflammation or irritation of the gut. A recent narrative review by Bajaj & Sharma (2025) examined how TFR influences the gut microbiome and leaking gut phenomenon leading to inflammation: " microbial diversity and function are enhanced by early-time-restricted feeding (eTRF), which synchronizes with circadian cycles. Changes in tight junction proteins have been linked to irregular meal timing, which increases intestinal permeability and inflammation."

Secondly, I began to experiment with TRF to see about augmenting body composition and hormones (namely my testosterone) since it was in the 200-300s and free testosterone always measuring well below normal ranges. Honestly, the diet made life very simple and uncomplicated and difficult to over-eat since you can only eat so much in a 8-10 hour window. However, Peos et al. (2019) explained continuous energy restriction can be difficult to sustain. If wanting to keep muscle and lose fat or lose weight, this could be a valid strategy. However, when I tried to increase my bodyweight 10-15lbs, I had to expand the feeding window to 12 hours to be able to consume 4500kcal at day at only 140lbs.

However, the article by Peos et al. (2019) is discussing the option of a strategy involving “refeed” or “diet breaks” which means that over the course of several months, the energy intake will undulate, having period of caloric surplus and deficit, but with overall net reduction in caloric intake leading to weight loss/ recomposition. I think it was interesting this review focused a lot on the potential negative/ unwanted endocrine effects of CER (continuous energy restriction).

Previous studies have demonstrated that CER for long periods of time (> 3 years) demonstrated significant changes which may be undesirable. For example, lowered thyroxine levels leading to adaptation in a lower REE (Fontana et al., 2006). Yet, a mild lowering in thyroxine might not be negative, depending on your goals. Lower thyroxine has been associated with slowing the rate of aging when paired with adequate protein and micronutrient intake.

Thus, maybe temporarily reducing thyroxine levels would be akin to doing periodic strict fasting for the purpose of general health. Recommendations of strict fasting for 2-7 days once a month can help stimulate increased autophagy and augment metabolic processes leading to improvement of aging, autoimmune, cancer, neurodegeneration, and cardiovascular diseases (Longo et al., 2021). Thus, health and performance can be tuned with not simply how much or what one eats, but when and how often they do.

References:

Bajaj, P., Sharma, M. Chrononutrition and Gut Health: Exploring the Relationship Between Meal Timing and the Gut Microbiome. Curr Nutr Rep 14, 79 (2025). https://doi.org/10.1007/s13668-025-00670-z

Fontana, L., Klein, S., Holloszy, J. O., & Premachandra, B. N. (2006). Effect of long-term calorie restriction with adequate protein and micronutrients on thyroid hormones. The Journal of clinical endocrinology and metabolism, 91(8), 3232–3235. https://doi.org/10.1210/jc.2006-0328

Longo, V. D., Di Tano, M., Mattson, M. P., & Guidi, N. (2021). Intermittent and periodic fasting, longevity and disease. Nature aging, 1(1), 47–59. https://doi.org/10.1038/s43587-020-00013-3

Peos, J. J., Norton, L. E., Helms, E. R., Galpin, A. J., & Fournier, P. (2019). Intermittent Dieting: Theoretical Considerations for the Athlete. Sports (Basel, Switzerland), 7(1), 22. https://doi.org/10.3390/sports7010022