Eat small meals 5 to 6 times a day to minimize hunger and maximize muscle gains. No, that’s all wrong…eat once a day, that’s how we are designed to eat! Wait, that’s seems extreme–maybe intermittent fasting is the answer–eat all your meals within an 8 hour window!! Or should I try to fast every other day, or every two days, or…ahhhhh!! So many opinions, so many books, so many testimonials! Optimal meal timing, optimal meal frequency, and fasting for optimal health–what does the research say?
Warning: certain medications (including but not limited to diabetic medications, blood pressure medications, and “blood thinner” medications) may need adjusted if there are major changes made to a diet regimen. Consequences may include harm or even death if these medications are not adjusted appropriately to match significant changes in your dietary patterns. If you take medications or have an underlying medical condition, discuss any plans to alter dietary patterns with your medical provider PRIOR to altering your current patterns.
Intermittent fasting and meal timing in the world’s longest lived populations
Researcher and professor Valter Longo PhD has an impressive resume. He serves as Professor of Gerontology and Biological Sciences and Director of the Longevity Institute at the University of Southern California –Leonard Davis School of Gerontology. Not only that, he also serves the role of Director of the Longevity and Cancer Program at the IFOM Institute of Molecular Oncology in Milan, Italy. His research into diet, meal timing, fasting, and aging are science-based and powerfully insightful. Much of his research to date is summarized in his book, The Longevity Diet (2018), available here.
Dr. Longo describes dietary habits of the world’s longest living, healthiest aging populations. His findings match the findings touted at Bluezones.com. Blue Zones are global hot spots where populations are found to age well, with:
- Lower rates of cancer
- Lower rates of osteoporosis
- Lower rates of heart disease and vascular disease
- Lower rates of Alzheimer’s disease
- Preservation of sex lives into their 90’s in some cases! (Mishra, 2009)
Dietary patterns of long-lived populations supports the value of breakfast and feeding time windows of 11 to 12 hours per day
Meal patterns in these regions note a concentration of calories in the first part of the day, with the evenings consisting of little to no caloric intake (Bluezones.com, 2020). The vast majority of these calories are plant-based, coming from beans, fruits, grains, and vegetables. Dr. Longo (2018) agrees with these dietary patterns, strongly recommending those desiring optimal health consume breakfast and eat a plant-based diet.
Additionally, Long (2018) recommends eating meals two to three times per day with one small, low-sugar, approximately 100-calorie snack. These meals should be consumed within 11 to 12 hours, to allow a fasting state of 12-13 hours. If your goal is weight loss, Longo (2018) recommends two meals with a separate 100 calorie small snack replacing the third meal. If your weight is low or your caloric needs are higher, recommendations are for three meals and a 100 calorie, low sugar snack consumed within an 11 to 12 hour period. Longo (2018) also recommends small servings of low mercury fish twice per week, whereas Bluezones.com recommends 95-100% plant-based diets.
Interestingly, while recommending fasting periods of 12-13 hours, Longo (2018) recommends against regular intermittent fasting of longer time periods such as 14-16 hours. He argues that such prolonged fasting periods raise stress hormone levels, are unnecessary, raise risks of gall stones, and even potentially increase risks of cardiovascular disease (Longo, 2018). Instead, for those who desire to explore the benefits of more intensive fasting periods, he proposes periodic fasting mimicking diets of 4-5 days duration.
Longo (2018) emphasizes the need for clearance from a medical provider before trying a fasting mimicking diet. The fasting mimicking diet consists of a 4-5 day period of restricted calories, such as 1,100 calories on the first day, then 800 calories daily from days 2-5. There are numerous important nuances to the fasting mimicking diet that are beyond the scope of this post. Those interested in learning more should refer to Longo’s book referenced above. Research studies on fasting mimicking diets are fascinating, though mostly consist of animal studies with some limited human studies to date.
Meal timing, frequency, and current research findings
“Eat like a king in the morning, a prince at noon, and a peasant at dinner” (Moses ben Maimon or Maimonides. 1135-1404) (as cited in Paoli, Tinsley, Bianco, & Moro, 2019, para 1)
Historical eating patterns versus modern patterns
Researchers note the frequent food intake pattern of three meals per day plus two or more snacks per day (5 or more episodes of food intake per day) is a modern phenomena (Paoli et al., 2019). For example, Romans were noted to eat a light, quick breakfast, light lunch, and heavier meal around 4:00pm (Paoli et al., 2019). Any more than this was believed to be unhealthy. Breakfast took on a more significant role during the medieval ages and again during the industrial revolution time period. These patterns appear to align with findings in both the Blue Zones and Dr. Longo’s recommendations described above, supporting 3-4 episodes of food intake per day. Eating late at night, including heavy meals later at night, became more common with the advent of artificial lighting (Paoli et al., 2019).
Meal frequency and health implications: where we got the notion of five or more “meals” (meals and snacks) per day
Research findings in the 1960’s noted higher cholesterol profiles in persons who gorged themselves with one or two meals daily versus those that ate more frequently with smaller meals (Paoli et al., 2019). The research findings held up even when accounting for age, alcohol intake, smoking, blood pressure, waist to hip measurements, body mass index and calorie/ nutrient intake. These findings were further supported with additional research conducted through the 80’s, 90’s, and up to current times (Paoli et al., 2019).
Indeed, eating one to two meals per day versus four to five meals per day has been associated with increased risk of diabetes (Mekary, Giovannucci, Willet,, van Dam, & Hu, 2012 as cited in Paoli et al., 2019), cardiovascular disease (Cahill, Chiuve, Mekary, Jensen, Flint, Hu, & Rimm, 2013 as cited in Paoli et al., 2019) and obesity (Holmback, Ericson, Gullberg, & Wirfalt, 2010 as cited in Paoli et al, 2019). While research supporting four or more meals per day spans more than 5 decades, more recent research on more than 50,000 Seventh Day Adventists has found that having more than three meals per day is associated with a greater BMI. Additional recent research also has linked frequent snacks to obesity and diabetes (Paoli et al., 2019). So what are we to believe?
Meal timing, content, and regularity appear to be more important than meal frequency
Meal time regularity, timing during the day, and content appear to be a key factors in determining the impacts of meals, satiety, and weight management. This is as opposed to focusing necessarily on meal frequency (Longo, 2018; Paoli et al., 2019). Our hormones, metabolism, and circadian rhythms appear to favor predictability (Kessler & Pivovarova-Ramich, 2019; Paoli et al., 2019). For example, those that eat only one or two meals per day may be less consistent in terms of their meal timing…
This in turn can lead to excess sensations of hunger and overfeeding. Conversely, when these meals are regularly timed, particularly if associated with a longer fasting period overnight, less frequent feedings are associated with better weight management (Paoli et al., 2019). Gorging in relation to excess hunger can lead to surges in insulin and cholesterol production (Paoli et al., 2019).
Front load your calories: breakfast with the most intake, taper down through the day
Our bodies are wired to respond with heightened metabolic activity early in the day, tapering off towards the evening as we wind down and then sleep (Kessler & Pivovarova-Ramich, 2019). In both animal and human studies, eating during the “wrong time”–such as when nocturnal animals are fed during daylight hours, or when humans eat larger meals late in the day to overnight hours–leads to metabolic and hormonal disruptions with significant health implications. Such patterns result in decreased insulin sensitivity, increased blood sugar levels, decreased metabolism of fatty acids, and disruptions to our circadian rhythms (Kessler & Pivovarova-Ramich, 2019).
Patterns established in the research show favorable health results when humans consume a larger breakfast versus when humans consume the exact same number of calories late in the day (Kessler & Pivovarova-Ramich, 2019). Those that ate the larger breakfast instead of the equivalent-calorie large supper had improved blood sugar levels, reported less hunger, had lower insulin levels, and lower grehlin (hunger hormone) levels. Also interesting, late or delayed eating resulted in disruptions in sleep hormones and stress hormones.
Those trying to lose weight when following a low calorie diet lost more weight if they ate breakfast versus delaying their intake till lunch time (Kessler & Pivovarova-Ramich, 2019). Why is this? It appears that our pancreatic beta-cells (which produce insulin), our body tissue’s sensitivity to insulin, along with our ability to metabolize calories effectively are governed by our circadian cycles to function most effectively in the early part of the day. These processes decrease in function later into the day and evening (Kessler & Pivovarova-Ramich, 2019).
Research on 51,529 healthy males (monitored from 1992 up to 2008) found that those that regularly ate breakfast had lower rates of cardiovascular disease during the study’s time period (Cahill, Chiuve, Mekary, Jensen, Flint, Hu, & Rimm, 2013 as cited in (Paoli et al., 2019). These findings were further supported in a subsequent study of 26,902 American men aged 45 to 82 years. Those that ate breakfast regularly had an approximately 30% lower rate of heart disease. Late night eating on the other hand raised cardiovascular disease rates by 55% (Cahill, Chiuve, Mekary,, Jensen, Flint, Hu, & Rimm as cited in Paoli et al., 2019).
Research supports eating your meals within an 8-12 hour period
Intermittent fasting is gaining recognition both in the popular media and in the research literature for its ability to improve health through a number of physiologic mechanisms. For example, overweight individuals who restricted their meal intake to a 10 hour window were able to sustain weight loss, boost their energy levels and reported improved sleep (Gill & Panda, 2015 as cited in Kessler & Pivovarova-Ramich, 2019). While fat mass decreased during time restricted feeding protocols in resistance-trained males, muscle tissue was preserved (Moro et al., 2016 as cited in Kessler & Pivovarova-Ramich, 2019) Intermittent fasting is also useful in stimulating cellular autophagy.
Autophagy is described as follows: “an intracellular process that mediates protein degradation, organelle turnover, and recycling of cytoplasmic components, is a fundamental process to combat cellular stress and preserve normal cell function” (Paoli et al., 2019, part 4 para 5). Autophagy is believed to play a significant role in protecting against diabetes, heart disease, hypertension, cancer, neuro-degeneration, and organ dysfunction (Antunes et al, 2018; Paoli et al., 2019). Autophagy occurs normally at a baseline level but can be boosted with fasting times beginning at around 12 hours, but increasing most notably at 16 hours or more, or during alternate day fasting patterns with at least two 24 hour periods of fasting per week, or when fasting for 3 day cycles every two weeks or more (Antunes et al., 2018; Kessler & Pivovarova-Ramich, 2019).
Time restricted feeding is noted to result in lower inflammatory cytokines such as tumour necrosis factor a, interleukin 6, and interleukin 1b in humans (Moro et al., 2016 as cited in Paoli et al., 2019). Further, time restricted feeding appears to boost parasympathetic (rest and digest) nervous system activity, reducing heart rate and blood pressure. However, consistent with research cited above, eating only one meal per day specifically between 5 to 9 pm was associated with elevated blood pressure and cholesterol (Paoli et al., 2019).
In summary, research based on randomized controlled trials, prospective cohort studies, observational studies, and epidemiological studies, along with expert opinion supports the following principles:
- Limit your food intake time windows to 8-12 hours, fast after your last meal of the day for 12 – 16 hours before eating breakfast the next day
- If possible, stop eating by 3 or 4 pm (Paoli et al., 2019)
- Eat the majority of your calories in the early part of the day
- Eat 2 – 4 “meals” per day (“meals” include snacks)
- Do NOT skip breakfast
- Eat a predominantly plant-based diet
- Research at this time supports MORE than 1 meal per day versus eating only 1 meal per day
- Regular intermittent fasting of 12-16 hours per day appears to boost autophagy over baseline rates without the discomfort or risks associated with prolonged fasting.
- More extreme regimens: If cleared and guided by a medical provider, in order to boost cellular autophagy, various PERIODIC longer fasting regimens (such as a fasting mimicking diet, 24-hour fasts up to 3-day fasts, or other options might be explored)–WARNING! Prolonged fasting regimens may be dangerous or even fatal if you take diabetic or blood pressure medications! There may be additional risks to such prolonged regimens based on various health conditions. Check with your medical provider before undertaking prolonged fasting regimens!
As we learn more about the science of meal intake timing, meal content, and fasting windows, it appears we have additional tools to support our goals of prolonging or restoring health. Any adjustment to an existing routine can be uncomfortable initially. For me, I started first by eliminating my 7-8 pm snack.
After getting used to this change, I eventually eliminated my 6:00 pm dinner. My body adjusted pretty quickly, and I routinely now eat my last meal at 3:00 or 4:00 pm. I do not feel hungry at night, and do not wake up hungry in the middle of the night. I believe anyone can adopt these changes in their lives, even if starting out by changing one meal at a time to a plant-based meal, or by eliminating one late snack or meal at a time. Small changes can accumulate into dramatic life changes and new healthy habits in time. Take charge of your health and life, even if only one step at a time!
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Antunes, F., Erustes, A. G., Costa, A. J., Nascimento, A. C., Bincoletto, C., Ureshino, R. P., Pereira, G., & Smaili, S. S. (2018). Autophagy and intermittent fasting: the connection for cancer therapy?. Clinics (Sao Paulo, Brazil), 73(suppl 1), e814s. https://doi.org/10.6061/clinics/2018/e814s
Bluezones.com. (2020). Top 10 best Blue Zones breakfast ideas. Retrieved from https://www.bluezones.com/2018/06/best-breakfast-ideas-for-eating-breakfast-like-a-king/
Longo, V. (2018). The Longevity Diet. New York, NY: Penguin Random House
Kessler, K., & Pivovarova-Ramich, O. (2019). Meal timing, aging, and metabolic health. International journal of molecular sciences, 20(8), 1911. https://doi.org/10.3390/ijms20081911
Mishra B. N. (2009). Secret of eternal youth; teaching from the centenarian hot spots (“blue zones”). Indian journal of community medicine : official publication of Indian Association of Preventive & Social Medicine, 34(4), 273–275. https://doi.org/10.4103/0970-0218.58380
Paoli, A., Tinsley, G., Bianco, A., & Moro, T. (2019). The Influence of Meal Frequency and Timing on Health in Humans: The Role of Fasting. Nutrients, 11(4), 719. https://doi.org/10.3390/nu11040719
Valterlongo.com. (2019). Valter Longo. Retrieved from https://valterlongo.com/biography/