One of the touted benefits of fasting and time-restricted feeding is weight loss. As someone who is lean and muscular at 82 and doesn’t want to lose weight, I’ve been reluctant to add any kind of caloric restriction to my current (rapa/metformin/empagliflozin/acarbose) regimen.
I could do a 16 hour fast from 9P to 1P the next day, and try to make up for the loss of breakfast calories. What I’ve been unable to find are studies supporting the idea that lean individuals benefit from time-restricted feeding. Is there substantial evidence that the benefits are independent of weight loss?
We conclude that both fasting and CR have a role in the upregulation of autophagy, the evidence overwhelmingly suggesting that autophagy is induced in a wide variety of tissues and organs in response to food deprivation.
And maybe there’s something interesting here, among the latest papers on autophagy and mTOR:
I too am lean with a current BMI of 21.2 and I am 81 yrs old.
I do time-restricted eating for three reasons: 1, Lowering fasting glucose levels and increasing insulin sensitivity. I am fighting an age-related increase in glucose levels and the fact that diabetes tends to run in my family.
2. It is natural for me. As a child, I never wanted to eat breakfast because I wasn’t hungry.
I am still not hungry in the morning and rarely have anything other than coffee before noon or 1 PM.
3. I do not seem to have to watch my diet to stay lean.
Effects of time-restricted feeding on body weight and metabolism. A systematic review and meta-analysis
“An overall significant reduction in fasting glucose concentrations was observed with TRF regimens.”
Time restricted eating for the prevention of type 2 diabetes
“TRE also reduces fasting insulin and improves insulin sensitivity in individuals with prediabetes and those with obesity. Moreover, TRE improves glucose tolerance and decreases serum glucose excursions” https://physoc.onlinelibrary.wiley.com/doi/abs/10.1113/JP281101
Time-restricted feeding and risk of metabolic disease: a review of human and animal studies
“Human data support the findings of animal studies and demonstrate decreased body weight (though not consistently), lower concentrations of triglycerides, glucose, and low-density lipoprotein cholesterol, and increased concentrations of high-density lipoprotein cholesterol.”
The diet debate is a tough one! It is easy to find data to support whatever you want to promote. I think-much like our ancestors, the answer likely lies in cycling. Periods of higher protein, higher fat, lower carbs and cycling with periods of higher healthy carbs, fruits, legumes and then periodic fasts or FMD 3-4 times a year for 3-5 days. That allows us to build muscle which is difficult to do when on a protein-restricted diet as well as maintain metabolic flexibility. We cannot forget that muscle is an endocrine organ, producing 1000 different myokines that influence all aspects of health-not simply something to protect us from falls! Thoughts?
Intermittent methionine restriction reduces IGF-1 levels and produces similar healthspan benefits to continuous methionine restriction
A sustained state of methionine restriction (MR) dramatically extends the healthspan of several model organisms. For example, continuously methionine-restricted rodents have less age-related pathology and are up to 45% longer-lived than controls. Promisingly, MR is feasible for humans, and studies have suggested that methionine-restricted individuals may receive similar benefits to rodents. However, long-term adherence to a methionine-restricted diet is likely to be challenging for many individuals. Prompted by this, and the fact that intermittent variants of other healthspan-extending interventions (i .e ., intermittent fasting and the cyclic ketogenic diet) are just as effective, if not more, than their continuous counterparts, we hypothesized that an intermittent form of MR might produce similar healthspan benefits to continuous MR. Accordingly, we developed two increasingly stringent forms of intermittent MR (IMR) and assessed whether mice maintained on these diets demonstrate the beneficial metabolic changes typically observed for continuous MR. To the best of our knowledge, we show for the first time that IMR produces similar beneficial metabolic effects to continuous MR, including improved glucose homeostasis and protection against diet-induced obesity and hepatosteatosis. In addition, like continuous MR, IMR confers beneficial changes in the plasma levels of the hormones IGF-1, FGF-21, leptin, and adiponectin. Together, our findings demonstrate that the more practicable intermittent form of MR produces similar healthspan benefits to continuous MR, and thus may represent a more appealing alternative to the classical intervention.
Intermittent methionine restriction reduces IGF-1 levels and produces similar healthspan benefits to continuous methionine restriction
I think that is very valuable information. I have tried to get answers to what I think are very good questions about the Fast Mimicking Diet from Valter Longo and his organization without success. For me, my most important questions are: 1) can a substantial amount of the benefits of periodic fasts (or FMDs) be had by 5 days of just the severe protein restriction especially methionine. For me and I think for most people, such periods of restriction would be relatively easy to do. 2) Would fairly frequent (say monthly) fasts provide substantial additional benefits to people who are healthy, have an ideal diet and exercise. He recommends twice a year for such people. I don’t get answers, possibly for economic reasons. My thinking is for me (and I think for many people) severe protein restriction for 5 days without severe calorie restriction would be easy and I would do it if there were meaningful benefits to be had.
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I doubt that methionine or protein restriction alone would give all the benefits of fasting. Our nutrient sensing pathways are also sensitive to carbohydrates, and, if I am not mistaken, total calories. Carbohydrate consumption, of course, activates an anabolic insulin response, and activates IGF-1; you want to minimize both of these responses during a fast.
I haven’t seen studies on the benefits for healthy subjects (human or animal) with increased frequency. My guess would be that increased frequency provides minimal additional benefits.
@Elizabeth.
Firstly welcome, and secondly, from my own personal experimentation, I broadly agree with your dietary cycling theory.
Specifically on my part I’ve noticed a protein restriction for a couple of months followed by an increase back to prior levels has resulted in a noticeable strength boost.
I wonder if it is more about putting certain stressors on the body as certain macro-nutrients are restricted that effectively makes the body stronger.
Regardless of the immediate health effects of meat, the dramatically negative environmental impact of the meat and dairy industries, the huge amount of antibiotics that are poured into these animals which increases emergence of antibiotic resistant bacteria, and the certainty of more deadly future viral pandemics arising out of of the fact that humans continue to unnecessarily over-consume meat are all more than enough reason for me to highly discourage meat consumption.
That is more or less my thinking at this point. Apparently, studies, many studies can be produced to “prove” quite a few different dietary approaches are of great value. I find many of the approaches such as keto, Longo’s longevity diet, etc. extreme. I do control my diet far more than most Americans. But, some of the things recommended would be a significant sacrifice for me. Even then I would probably make the sacrifices if I were reasonably sure that meaningful benefits would be had. As best I can tell at this point moderation (eating reasonably healthy things, not Big Macs and ice cream) is the best approach.
Researchers take this approach too. They want to discourage meat eating or seek to affect peoples behaviors in a certain way and make their studies “show” the results they want in order to influence people’s behavior. I would instead like to get correct information about diet and health and longevity. This probably won’t happen in the near future.
When it comes to potential bias, I think it’s important to keep in mind that the meat and dairy industries (much like the gas/petroleum industry aka Big Oil) have extremely powerful lobbies and purses to fund and influence research. There’s no such thing as “Big Broccoli”.
Also, most people (including me) enjoy the taste of meat. That’s a huge potential source of bias as we “consume” information, whether directly from research articles or from the media.
Although their analysis may be true, that meat-eating is associated with longer life, they did not seem to take into account eating greens and other non-starchy vegetables and fruits explicitly. They didn’t even mention it. The major distinction made was between meat and carbohydrates as energy sources. Without controlling for the greens eaten, their conclusion is questionable.
Control diets (CON) contained 20% casein (by weight) as the protein source, while the low protein diet (LP) contained 5% casein (Casein comprises around 80% of the total protein in cow’s milk, while whey accounts for the remaining 20%. Whey is the liquid part of milk, while casein is the curds)
“Recent work indicates that the hormone FGF21 mediates the metabolic effects of protein restriction in young mice. Here we demonstrate that protein restriction increases
lifespan, reduces frailty, lowers body weight and adiposity, improves physical performance,
improves glucose tolerance, and alters various metabolic markers within the serum, liver, and
adipose tissue of wild type male mice. These data demonstrate that protein restriction in aging male mice exerts marked beneficial effects on lifespan and metabolic health and that a single metabolic hormone, FGF21, is essential for the anti-aging effect of this dietary intervention.”
This is consistent with a plethora of other studies showing lowered protein, especially BCAA, increases lifespan in mice. Animal protein is highest (aside from engineered plant foods) BCAA content.
I emailed authors asking about any measurements of p-mTOR and association with longevity benefits.
Meat protein consumption and associations in humans may be lumped into the MUCH larger problem in western societies, namely OVER-NUTRITION/EXCESS energy consumption, and the resultant obesity/diabetes crisis and plethora of comorbidities and lifespan reducing outcomes. So meat, per se, gets a bad rap due to it’s overconsumption and high calorific content. It likely has an outsized impact on longevity, but at LOW % MACROS on a low calorie/BMI diet protocol, may be perfectly fine. Humans most definitely evolved as omnivores…just look at your molars.
Okinawans, the “long lived” population, have been shown to be in a state of CR, ergo, likely low protein.
“A study of older Okinawans demonstrated that they appear to have undergone a mild form of prolonged DR for about half their adult lives”. By default, low protein. Long lived Sardinians/Okinawans/Cretans, wide variety of diet…commonality, low animal protein.
List of countries by food energy intake
The US is #2 in the world in energy consumption per capita, yet 54th in the world in life expectancy.
And drum roll…the US is the highest expenditure per capita in healthcare.
(filter in ascending for 2019)
Imagine the average life expectancy without the massive healthcare spending to keep Americans alive? The US would be way further down than 54th.
Even with rapa, keeping BCAA low might have an additive effect–we just don’t know. I eat meat all the time, but I keep serving sizes quite small, typically one or two ounces.
Eating BCAA elevates mTOR, a fact. Leucine is a major trigger for mTOR/IGF-1.
I am trying to eat less and less animal protein as the years pass. I am already on a strict keto diet, so my meat/animal protein intake is below normal, and I continue to progress in muscle/health, so I keep tweaking away from animal protein, whilst maintaining muscle mass. I have come to see the light in muscle physiology: it’s the resistance exercise, NOT the protein that is critical. As Dr B once told me “resistance exercise builds muscle, not amino acids”.
But I cannot imagine going pure vegan and complete abstinence. There are way too many macronutrients in a varied, whole food animal protein diet. Besides, (full disclosure, foodie), what tastes better than wild venison or gorgonzola?