Thoughtful Thursday…Fasting for longevity or fat loss...is there a difference...?
Welcome to Thoughtful Thursday. This GreenNote Fitness newsletter mindfully gathers and distills useful information that is supportive to our journey. It is my mission to educate, inspire, and propel you into action that moves you towards your goals and life of purpose. Take control of your journey today.
I first began intermittent fasting on a regular basis almost a year ago. I’ve written about that here. As it explains, the process of autophagy assists the cells repair themselves which helps in part to slowing the markers of aging and improve longevity. I’ve also written about my fasting results of weight loss and body fat.
So when it comes to fasting, is there a difference between fasting for longevity and fasting for fat loss?
You are about to find out!
We know that decreasing our caloric intake by 20% to 40% regulates aging and increases life span as this study explains. Further, we know that longevity is synonymous with autophagy. Autophagy or "self-eating” is a process that removes toxic or damaged parts of the cell and repairs the parts that remain. So, the oldest cellular parts get discarded - think of it as Spring-cleaning in your cells. Note it doesn’t kill off the entire cell as with apoptosis, just the old cell membranes or organelles. We can allow the body to engage in a natural cellular cleanup in as little as 12 hours of not eating. More than 12 hours of not eating simply increases cellular cleanup or autophagy.
For longevity there are three specific ways fasting provides benefits:
Stimulating autophagy - as mentioned, this cellular cleanup gets rid of toxic or damaged parts. Fasting increases autophagy so conversely, the more amount of time you eat every day, the less amount of autophagy occurs. As Dr. Jason Fung reminds us that we need a balance, “You get sick from too much autophagy as well as too little. Which gets us back to the natural cycle of life - feast and fast. Not constant dieting. This allows for cell growth during eating, and cellular cleansing during fasting - balance."
Inhibiting mTOR pathway - mTOR, an “energy enzyme”, is a key autophagy regulator. In short, mTOR manages processes that generate or use large amounts of energy. This includes cell growth, protein synthesis, and autophagy. Note that when mTOR is activated, it suppresses autophagy. When mTOR is not activated, (which occurs when fasting), autophagy increases. Every time you eat, you activate mTOR and suppress autophagy by increasing insulin and amino acid levels. Basically, mTOR activated = autophagy suppressed.
Inducing ketogenesis - fasting regularly can help optimize autophagy and the mTOR pathway, but it also provides the benefit of shifting your body into cyclical ketosis. Ketosis occurs when your body utilizes fat - more specifically as ketones - rather than glucose (carbohydrate) as its primary fuel. When burned as the primary source of fuel, we see less oxidative stress which can slow the aging process. Are there ways to do so besides strict ketosis? Yes, by lowering the glycemic variability, eating a diet rich in legumes and slow-release carbs, and by avoiding starches and sugars.
Autophagy is a catabolic process (breaks things down) where as mTOR is anabolic (it builds things up). Bottom line, eating shuts down autophagy and fasting increases autophagy. We need not one or the other but a balance between the two - cycle between periods of fasting and periods of eating.
In as little as 12 hours without eating, we can start to obtain the benefits of autophagy. This would mean having zero calories for 12 or more hours. No cream or butter or anything in your coffee as well as no supplements as these would technically break your fast if fasting for longevity.
What about fasting for fat loss - how does it differ from longevity?
Good news! When fasting for fat loss or body composition, we don’t have to be as strict as we do when fasting for longevity. We know that intermittent fasting for 12-16 hours or a mild amount of calorie restriction can help with body composition. The calorie restrictions though are not as absolute as when fasting for fast loss.
Not as strict of fasting would mean for example, instead of having just water or plain coffee or tea, you could include a little fat like MCT oil or coconut oil in coffee or tea. Instead of strictly no supplements, you could have for example, fish oil or amino acids. I personally will sometimes use amino acids before an intense fasted morning workout. This helps to maintain muscle levels.
Having a little bit of energy going into a meeting or an intense workout by having coconut oil in your coffee or taking small amounts of supplements is but a small speed-bump towards autophagy. When fasting for longevity, the stricter you fast, the more you activate many of these mechanisms we discussed. I will do some of both, so one or two of my fasting days will be strict with no calories, and one I may use supplements prior to an intense morning fasted workout.
To summarize the difference between fasting for longevity and fasting for fat loss:
Fasting for longevity
Fasting needs to be stricter, more frequent, and longer
Liquids such as water, tea or plain coffee are OK
Supplements should be avoided which includes fish oil and amino acids, etc.
Fasting for fat loss
Doesn’t have to be a strict water only, no-calories
Including coconut oil or MCT oil in coffee or tea is fine
12-16 hours or even mild amount of calorie restriction helps in fat loss
Just be mindful that your body thrives by following a cyclical approach to eating and digestion. …which gets us back to the natural cycle of life - feast and fast. The great thing about fasting for longevity or for fat loss is it’s completely free! No subscriptions or downpayment needed. Sounds like a good deal to me!
Ready for a little cellular cleanup?
Feast and fast - not constant dieting - cell growth during eating, cellular cleansing during fasting - feast and fast...
Enjoy your journey,
Lisa Schaffer
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