When we hear the word “fasting”, I don’t know about you, but I think of starving. I tried out a fast to “reset my digestive system" and as part of a cleanse. I remember drinking copious amounts of water and being miserably hungry by day 2. Afterwards I was so happy just to eat that I can’t even remember much of the benefits, though there definitely were some. I could also have been more prepared for the fast so that it wasn’t as bad. That’s on me, but now I know better. Also, any water weight lost during that time, just came back when I went back to eating regularly. I do not imagine that this result is specific to me or even uncommon. Intermittent fasting is quite different and actually involves eating (happy dance!!), but still has immense benefits to our bodies. Read on to find out what they are.
What Is Intermittent Fasting?
Intermittent fasting is actually something that you already do, you just probably call it something else: sleeping. People generally sleep between 6-9 hours during the night and during this time, they are not eating. This is fasting and why we call the first thing we eat the next day breakfast. Because we are breaking the fast that we did during the night.
People who “do” intermittent fasting, simply do this in a more deliberate way. They choose a timeframe in which to eat all of their calories for the day (see? Eating!) and then they stop consuming anything for a decided amount of time. This can be 12, 16, 24 hours… Whatever you want it to be, as long as it’s over 12 hours. The best window is an 18 hour fast and 6 hour eating phase, as after 18 hours of fasting your insulin levels are pretty much as low as they’re gonna get. You’re not restricting the amount or even kind of food you eat, you just reduce the number of hours in the day that you spread this eating over. Sounds doable, right? It totally is and it’s worth the small effort it takes too. It’s a healthy weight loss tool that increases your gut health and metabolic health.
The Scientific Backing for Intermittent Fasting
By now, I’m sure you all know that I love some significant scientific backing behind any claims I make here and this is no different. So let me explain the way intermittent fasting works. It’s not the newest, shiniest fad diet. It all comes from biological processes and makes total sense when you hear it.
The Evolutionary Reasons for Fasting
If you think back, as long ago as the beginning of mankind, humans did not eat continuously. They hunted and gathered and ate huge amounts of meat when they caught an animal worth eating and small amounts of berries in between. The feasted and fasted. So from an evolutionary point of view, this is what our bodies have been designed to do. The few millions of years that have passed between now and then are not enough, in terms of evolution, for us to adjust to any change in this behaviour.
Furthermore, an abundance of food has only been a relatively recent thing to humans and still doesn’t apply to the majority of the species. Billions of people are still starving and eating as much as they can when the opportunity occurs as they know they’ll be without food for a while again afterwards. So evolution would be doing a disservice to the human race to develop us to survive any other way. Even as close at the 1970s, people did not eat continuously throughout the day. They had breakfast, lunch and dinner and if you asked your mum for a snack, you were taking a risk. “You’ll spoil your dinner” was a pretty common response not so long ago when asking for extra food.
The Metabolic Science Behind Intermittent Fasting
This is the part that I find really interesting. We get to do some molecular biology, but I promise it’s not complicated and boring. There are even pictures.
Actually, let’s back up a bit, I want to define a carbohydrate for you. A carbohydrate is a long-chain molecule with a carbon backbone. The complex carbs that we eat are made up of glucose molecules joined together as a chain. These chains have variations on the side chains that branch off of them and in how they join together.
When we eat carbohydrates, our bodies take these chains and break them down into glucose. Glucose is then broken down further to produce energy, known as ATP. This is what our bodies use at a cellular level as an energy source. When we fast, even just overnight, we’re not consuming any carbs, or anything at all, to provide more glucose. During this time the amount of available carbohydrate that can be broken down into glucose decreases as our bodies use it up. Once there is no glucose left to be made into energy, our bodies go looking for new fuel. This is when they find the fat cells.
Fat is the second favourite food source of our bodies, after glucose. When we start burning fat instead of glucose, it breaks down into ketones and this is what’s used to make ATP now. This kind of metabolism is called ketogenesis and will continue until we provide our bodies with a renewed source of glucose to use. Ketones are actually a better source of fuel for our brains so we think more clearly during ketogenesis. It’s also when the stored fat in our bodies is broken down, resulting in weight loss.
The Benefits of Intermittent Fasting
Many people use intermittent fasting as a means to weight loss, because of the above mentioned fat burning properties you gain. While this is an outcome of intermittent fasting, it’s actually a side effect of an overall improvement in health. When you’re body functions better, it looks better.
Intermittent Fasting May Prolong Life
In both bacteria and yeast, moving them from a nutrient rich medium to a starvation environment has actually prolonged their lifespan. When yeast, in particular, moves into a starvation state, it switches its metabolism from using amino acids and glucose as a fuel to using ethanol and acetic acid. It will continue to do this until a glucose source is re-introduced. This is very similar to the way that humans will switch over to using ketones when glucose runs out. In this starvation state, yeast starts to change the genes that are active in its DNA. The yeast then produces stress-resistant responses, antioxidants to protect its DNA and undergoes autophagy. Autophagy is the breakdown of dead cells and the recycling of their components. This is involved in the aging and lifespan of the yeast. Overall, this causes it to actually live longer.
Similar studies on mice and rats found similar findings. Intermittent fasting, when started after the mice were 16 months old, increased the lifespan of the rodent. Interestingly, when mice with tumours were given an intermittent fasting diet, the tumour growth decreased significantly and in some cases even stopped. This suggests that intermittent fasting could be an aid in cancer treatment. It may even increase the toxicity of chemotherapy to cancer cells without causing extra damage to healthy cells through the T-cell response. Inflammation, especially skin disorders, went down by 50% in rodent studies and immune responses were 3 times higher than the mice that were in the control group eating regularly.
Your Brain Prefers Ketones As A Food Source
During a 7 month intermittent fasting study, mice were found to have enhanced cognitive performance. Meaning that they became smarter and performed better in a series of experiments that tested their short-term and long-term memory and motor functions. Scientists think that fasting encourages the creation of new brain cells and neurones and this is the reason.
Intermittent Fasting And Weight Loss
So you know that weight loss is not something I’m an advocate of. Being healthier is a great thing to aim for, but if you just want to be skinnier, there’s a psychological issue there that we need to address. However, we do need to touch on this as intermittent fasting does result in weight loss. As I mentioned earlier though, this is a side effect. You can see the same weight loss results from a restricted calorie diet, but what you won’t get from that, which intermittent fasting will give you, is the metabolic changes your body produces.
Intermittent fasting causes an increase in insulin sensitivity, meaning that you need less insulin to regulate your blood sugar. This causes weight loss as insulin is a promoter of fat production. It signals to your body that there is excess sugar in your blood and your body stores it away as fat for later use. Eating sugar causes fat cell formation, not eating fat. Along with a reduction in insulin resistance, intermittent fasting also reduces visceral fat, not just surface fat.
Inflammation is the cause of many diseases such as arthritis and asthma. Intermittent fasting reduces the symptoms of arthritis even after returning to a normal diet after a fasting period. I’ve found this myself. Though I don’t have arthritis yet, I have a lot of joint pain. I believe that it mostly comes from wear and tear during many years of martial arts where I wasn’t so careful with my knees as I should have been. But then, you never think of these thing when you’re 16 and joint pain is for old people.
After 3 weeks of intermittent fasting and ketogenic eating followed by a 3 day fast, I was finding that I could walk significantly further than normal without any pain. Whereas usually I would have had to sit down and rest or suffer sore knees, hips and ankles. Intermittent fasting also causes a reduction in the inflammation markers in asthmatic patients and patients with high blood pressure and hypertension also saw reductions in blood pressure following a fasting period.
Basically, intermittent fasting is pretty awesome. It allows your body time and space to heal itself by not spending so much energy on constantly digesting the food that we consistently fill our guts with, whether we are hungry or not. It reduces disease and inflammation as well as creating a whole host of benefits at a cellular level that I didn’t even go into. If you are interested in the biochemical processes of intermittent fasting, I recommend this paper:
For the purposes of the blog though, I’ve tried to keep this article accessible to everyone and not just scientists who understand the jargon. I hope that it’s given you an insight into how you can help repair your body, and yes lose weight fast, without “dieting” or starving / restricting / depriving yourself of nutrition. This should not be your purpose though. You always be health focused, not weight focused. Leave me a comment below and let me know if this was article was helpful. Did you find that it left you wanting to read more or did I lose you along the way somewhere? Do you feel inspired to try a shortened eating window? I’d love to know your thoughts.