Nutrition — Time Restriction

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Avoid or do less.

  • Constant feeding…

What to do.

  •  Routinely:
    • Time restricted feeding most interesting and practical (“FoundMyFitness — Satchin Panda“)
      • Squeeze three meals into relatively short time period.
      • Late breakfast, normal lunch, early dinner.
      • Align with circadian rhythm.
      • Provide fuel in the morning when needed.
      • Reduce fuel intake at night when not needed.
      • More or less, business as usual…
  • Periodic:
    • Longer fasts.
      • 3-5 days water-only fast.
      • Material benefits of fasting and re-feeding cycling program.
      • Ketosis and potentially autophagy.

Three forms of nutrition restriction.

  • Time restriction (when you eat).
  • Caloric restriction (how much you eat).
  • Diet restriction (what you eat).

Key Takeaways:

  • Fasting and feeding are distinct programs within the metabolic cycle.
    • Each part of the cycle has distinct benefits.
  • Fasting activates a shielding and repair mode that we lost access to over time.
    • Ancient program that has evolved for self-repair in times of famine.
    • This program is no longer triggered due to constant feeding.
  • Cycle of destruction (fasting) and reconstruction (feeding):
    • Strengthen normal cells.
    • Weaken (and consume) damaged cells.
  • Daily time restricted eating may be the easiest to maintain.
    • Eating in 4-12 hour window in sync with wake/sleep cycle.
    • Likely to have modest benefits (weight control, better diet, less snacking).
  • Periodic prolonged fasting may be most beneficial.
    • Chance at robust cycling benefits: autophagy, shrinking organs, etc.
    • Likely that 3 day fast is minimum period for achieving benefits.
  • Practical considerations for longer fasts:
    • Water only, maybe supplement with sodium (bouillon), sleep can be affected, likely feel colder, able to exercise (strength rather than endurance).

Three forms of nutrition restriction

  • What you eat: dietary restriction (DR).
    • Restricting some kind of macro-molecule (protein, carbs, fats).
    • Figure out what you to restrict or avoid (eg, sugar, PUFAs, etc.).
    • Figure out what to focus on: macro and micro (vitamins). 
    • Add supplements if/when needed.
  • When you eat: time restriction (TR).
    • Restricting the window during which you eat.
    • Daily:
      • Avoid lengthy eating windows.
      • Late breakfast, normal lunch, early dinner.
    • Periodic:
      • Long fasts (3-5 days water-only).
  • How much you eat: caloric restriction (CR).
    • Reducing the inputs.
    • Don’t overeat.
      • Generally, portion control.
      • Specifically, match to goals (health, training, etc.)
    • Potentially some rules of thumb to consider.
      • Grams of daily protein, fists of veggies, etc.

Fasting = time restriction.

  • Traditionally involves focus on nutrient composition and caloric intake to optimize diets.
    • Food provides energy and nutrients.
    • Necessary to sustain life and allows growth, repair, and reproduction.
    • Proper nutrition can influence health and survival / onset of chronic diseases.
  • Emergence of focus on fasting: adjustments of meal size and frequency.
    • Periodic absence of energy intake appears to improve multiple risk factors.
    • Tool to ameliorate and postpone the onset of disease and delay aging.
  • Underlying physiological processes of fasting involve:
    • Periodic shifts of metabolic fuel sources.
    • Promotion of repair mechanisms.
    • Optimization of energy utilization.
  • Shown to have positive effects on ageing and age related diseases across different animal models.
    • Questions about applicability to humans.
    • Animals have vastly different metabolic cycles – for instance, in relatively short fasts, mice loose up to 20% of their body weight.
  • Different fasting protocols vary in time fasted and caloric intake.
    • Common denominator of various types is initial suppression of IGF-1 pathway.
  • Fasting protocols that are the most effective and maintainable:
    • Prolonged fasting and fasting mimicking diets.
  • These types trigger cycles of destruction and renewal:
    • System is reset to a more youthful state, including lower inflammation.
    • Shown to impact systemic inflammation, blood glucose levels and other ageing biomarkers.
    • Potential to use fasting protocol as complementary therapy in cancer and other diseases.

Fasting and feeding are distinct programs within the metabolic cycle.

  • Fasting and feeding are two different programs.
    • Fasting: shielding and repair mode.
    • Fed: grow and reproduce.
  • Fasting activates a shielding and repair mode that we lost access to over time.
    • Ancient program that has evolved for self-repair in times of famine.
    • This program is no longer triggered due to constant feeding.
  • We do not know why the repair mechanism happens only during the period of fasting.
    • Likely: some genes are involved in both repair and nutrients signaling.
    • Can’t do both at the same time.
  • Also highlights that during time of fasting, energy has to come from different source:
    • Protein (gluconeogenesis).
    • Fat (oxidation), producing ketone bodies.
    • Ketone bodies.

Each part of the cycle has distinct benefits.

  • While fasting:
    • Low IGF-1
    • Triggers temporary destruction of white blood cells (autophagy, apoptosis).
    • Shrinking of the organs.
    • Triggers activation of (hematopoietic) stem cells (needed to replenish white blood cells).
    • In effect, recycling the immune system.
  • While re-feeding:
    • High IGF-1.
    • Triggers proliferation of stem cells.
    • Regrowth of organs, healthy cells.

Resulting in differential stress resistance (strengthen normal cells, weaken damaged cells).

  • Cycling strengthens normal cells, weakens damaged cells.
  • Healthy cells:
    • Starving the system triggers a cell’s “resistant mode”.
    • This limits the impact on healthy cells of potential other toxics (from chemo or other therapies).
  • Weak (cancer) cells
    • Are used to a high nutrient environment.
    • Lack of nutrients (especially protein, glucose) forces cells to use fat instead.
    • The use of fat triggers the release of Reactive Oxygen Species (ROS), which cancer cells can’t handle. (anti-Warburg effect).
    • Net effect is weakening of cancer cells for further destruction by standard of care therapies (chemo, etc.)
    • Also makes cancer cells easier to detect by the immune system.

Types of fasting: caloric restriction (CR):

  • 20-30% reduction in calories, no restriction on feeding times.
  • Known for >100 years to have beneficial effects.
  • Major drawbacks:
    • Very difficult to maintain.
    • Substantial side effects: weakened immune system prolonged wound healing, bone thinning.
    • Lowers all markers indiscriminately, regardless of where you start; so if markers are good / normal, lowers them further to “below healthy”.
  • Does not achieve dual benefits of fasting and re-feeding cycles.

Type of fasting: time restricted eating (TRE):

  • Eating in 4-12 hour window in sync with wake/sleep cycle.
  • Notion that the timing of feeding and triggering the fasting response matters – importance of:
    • The amount of time spent eating during each day.
    • Timing of food consumption relative to circadian rhythm.
  • Try to sync with evolutionary evolved patterns (when did we have access to food, wake/sleep cycles).
  • No specific dietary intake restrictions (ie, no restrictions on what to eat).
    • Makes it easier to maintain than caloric or other dietary restrictions.
    • Still likely to have positive impact on diet (likely to skip late nights snacks, alcohol, etc.).
  • Highlights importance of syncing body circadian clocks and metabolic pathways.
    • Many DNA repair pathways are time sensitive (ie, more active at night).
    • Insulin sensitivity is lower at night (melatonin inhibits insulin secretion in the pancreas).
    • Relevant for intake of food, as well as meds / supplements, surgery.
  • Key benefits:
    • Increased lean muscle mass, decreased fat mass, increased endurance [mice].
    • Mild ketosis [mice].
    • Cardiovascular health (less mitochondrial damage, improved protein folding) [fruit flies].
    • Microbiome (more diverse bacteria, less acid reflux, improved bile acid function, lower cholesterol) [mice].
    • Lower inflammation (less leaky gut issues through better gut repair, lower blood sugar through less eating when insulin sensitivity is low).

Types of fasting: intermittent fasting (IF) and prolonged fasting:

  • No or few calories are consumed for periods of time that range from one to several days.
  • Intermittent fasting:
    • Restricts both eating time and calorie intake.
    • Various types:
      • 12+ hours fasting/day
      • 2 day lower calories / 5 day normal.
      • 1 day a week fast.
    • Achieves modest cycling benefits.
    • Mainly triggers ketosis, weight loss.
    • Ignores importance of timing of meals with circadian rhythms.
  • Prolonged fasting
    • 3-5 day or longer water fasts.
    • Difficult to maintain, especially for non-healthy individuals.
    • Achieves robust cycling benefits.
    • Autophagy, apoptosis, organ shrinking.

Types of fasting mimicking diet (FMD):

  • Created to try and make fasting more acceptable/doable.
  • Low-carbohydrate, high-fat diet.
    • for 5 days periodically.
    • Low protein, low sugar, vegan, lots of “good fats”.
    • About 800 calories a day in total.
  • Enhances compliance by avoiding complete deprivation of food.
  • Simulates effects of prolonged fasting.
  • Sample 5-day diet:
    • Day 1 – 1,090 calories (10% protein, 56% fat and 34% carbohydrate).
    • Days 2 through 5 – 725 calories (9% protein, 44% fat and 47% carbohydrate).
  • Also achieves robust cycling benefits.

Sources and links:

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