To many people it happens more than once per day: They stop eating. (Not sure, if you got me? You did.) After the last meal minutes become hours, and soon half a day has passed without facing a bite. The body goes towards the fasting state. Many of us do it without even knowing yet some get there on purpose: The breakfast skipping. The non-snacking. The sleeping. Fasting has many faces but what’s the deal with it? Hungry as you are, I’ll explain to you.
To begin with, fasting is since ancient times a healing practice of willing abstinence or reduction from food or drinks (sometimes both) for a defined period, and can be put into spiritual, religious or medical context. It might however be all traced back to the observation that our bodies naturally tend to fast during times of stress or illness – targeting the energy spent for digestion to the “weak spot” (mechanisms a trendsetter once started calling “detox”). People who go on a fast usually don’t consume more than a maximum of 500 calories per day and for preparation of a longer period without food it is often combined with a (rather shitty business) of bowel rinsing. Well, this just to touch upon the vast scope of fasting… I don’t want to go too deep into the origin or application of it as healing practice. The severe energy restriction linked to these methods artificially introduce a starvation mode, not uncommonly used for the sake of weight loss. However, applied as dieting you may want to discuss the aim or approach of your fasting with a doctor or dietitian (…or nutritionist, yes we exist out there) in order to understand it properly or even avoid unappreciated side effects.
So, the organism’s first fuel for energy is glucose. Simple. I mean simple sugar. Carbohydrates to be more fancy. Glucose can be directly sourced from food delivered to our cells but the sooner or later after our last meal low blood sugar levels call for action. By this time we often feel hungry – maybe a primitive signal and not impressive yet – but it’s at this stage we can say the body begins to “fast” (when it starts living on its own energy sources). The easiest way to replenish blood sugar levels thereby is the release of glucose primarily from the liver, however, as this storage is limited soon fat is converted into glucose: Fat is burnt for energy. And BAM, there’s all eyes on fasting. Well, it’s true that the fasting mechanism can be used in favour for weight loss.
However (and for this reason I many times reconsidered squeezing it all into one article) weight loss is complex. You might argue: Wait, you many times mentioned the equation “Calories in versus calories out.” Fair enough. Ok, let me rephrase then: Sustainable weight loss is complex. As long as you consume less calories as your body needs you will lose weight but any temporary diet even though initially successful will fail at the time you go back to “eating normal”. And no, I’m not talking about the “yo yo effect” as it is often told to be linked to the loss of muscle mass slowing down our metabolism. Rather a myth than a fact. Even for fasting over several days muscle protein is the last substrate used for energy. Its mobilization from body tissues simply takes too long and it carries little energy per unit thus other substances are prefered: After glucose and fatty acids themselves ketone bodies (converted from fatty acids) are the magical fuel your body can effectively use for energy. Or: Damn, we are bloody efficient! Anyways, assuming you are disciplined but not gonna go for the 5 days without eating straight you probably don’t care. What seems more interesting to you on a rather daily application is the looong breaks in between your meals. I can understand you must be already confused around the ever-changing recommendations regarding 3 or 5 meals per day. And I feel you, I’ve been there. Insulin levels back and forth, up and down etc… in the end science is still controversial about how many meals per day are good for you – from where we could conclude: Whatever works best for you! While 5 hours without food already get you “starving” or craving for more and junk food you may just need a snack between your meals to avoid the binge eating after being hungry.
And back to talking about protein – everyone’s favorite topic! Even if your body won’t “eat” your muscle for energy as quickly as some literature scares the sh*t out of you protein turnover is a true story: There is a certain demand of protein that needs to be covered by our daily diet which is needed for the production of enzymes and reparation of body tissues. Our bodies are under continuous reconstruction and proteins are one of the major type of building blocks.
However, in the end many studies show that not even after days of fasting people significantly decreased in muscle mass. On the downside of it, muscle mass cannot be increased either when we have a negative energy balance. – And another factor to sustainable weight loss is? Yes, muscle mass for increase of total energy demand. Again, I’m not talking about bodybuilders here who do the diet cycling and at times consume 4000 calories to bulk their muscles and have a much higher energy demand to maintain them – and believe me, for these athletes every gram of mass less hurts!
Anyways, I know there are still many question marks left that just YOU wanted to know about achieving your weight goals but I decided to leave you hungry for more (…maybe cause that was the theme of this article hehe). Don’t worry, you just got me started. What’s however the message I wanted to put across is: For some people any form of fasting may work as a part of their lifestyle but as a temporary solution aiming rapid weight loss it may just lead to the same effect as coming from any other diet. And here we actually talk yo yo effect! After diet cycling many people get back to the same lifestyle as before. Instead of just focusing on calories you may want to consider that eating on a more frequent basis throughout the day gives you a higher chance to vary your food and increase your intake of micronutrients such as vitamins and minerals as well. Overthink your diet habits and sustainably replace with healthier choices instead.