Intermittent fasting has gotten a lot of attention recently as there are so many benefits to be had from it. It helps you lose weight, helps you gain muscle, helps sharpen cognitive performance, it lowers insulin- the fat storing hormone, it dramatically lowers your chances of developing type 2 diabetes, it raises human growth hormone, which does everything from increasing muscle mass to making you look better and live longer, and it promotes the release of BDN, brain derived neurotrophic factor, a key hormone for growing new brain cells. It does all this and it does it simply by you restricting your eating window each day.
In its simplest form IF, (intermittent fasting) asks only that you eat for 8 hours a day, while fasting the other 16, half of which you will be asleep for anyway. This is very easy for most people to do but you can also mix things up a bit with longer and shorter fasting days, on and off fasting days, half week fasting days, alternative fasting days or just about any combination of eating and fasting that you can think of. It even works well with any different eating protocols, for example going low carb, keto, paleo, or using carb cycling eating patterns. In fact lower carb eating and IF work particularly well together
However there is one aspect of Fasting that tends to cause some trepidation for the uninitiated; HUNGER. Even the sound of the word can have perspective dieters running to the patisserie for some nutritional comfort.
But what is, “Hunger,” and is it something to be feared? Is hunger just a signal that our tummy’s are empty. Perhaps its our body crying out in need for food to survive? Could it just be a habit. If I eat everyday at 6.00 do i start to feel hungry at 5.30 just because of my routine? Will i get hungrier and hungrier the longer i fast? If you are considering undertaking IF to lose weight, feel healthier or to live longer it might help to be able to answer these questions; to better understand hunger and deal with it.
The first thing to note is that hunger is NOT a simple equation of no food plus time equals greater and greater hunger. Hunger is triggered by a hormone called Ghrelin and it comes in waves, rising for periods of time and falling for periods of time. The rising and lowering tides of Ghrelin seems to depend far more on when you usually eat rather than your bodies actual need for food. In his fasting blog, Dr. Jason Fung, points to a study that shows that the Ghrelin levels of subjects that went over 3 days without any food continually decreased over the course of the trial. He says: “This means that patients were far LESS hungry despite not having eaten for the past 3 days. This jives perfectly with our clinical experience with patients undergoing extended fasting. They all expect to be ravenously hungry, but actually find this is not the case.” So hunger it seems is not always a good indicator of our need for food.
Another study was carried out at the Medical University of Vienna on subjects participating in a 33 hour fast. In this study it was noticed that despite the early morning being when people had gone the longest without food, Ghrelin was at its lowest. Also, the participants Ghrelin levels didn’t rise more and more the longer they whet without food but rather, rose at the normal eating times for the participants and then fell back down even though they hadn’t eaten anything.
When you start fasting, it’s important to know that hunger will arise and it is a little uncomfortable at first, but it will come and go. After a couple days, your hormones will adapt to your new eating times and you will be less and less hungry until it’s no longer an issue. This is why many people say that the first 4 days are the hardest. Un-adapting and re-adapting your eating times can be a little uncomfortable, but your body is very good at it. After 2 weeks most people report no sensations of hunger outside of their chosen IF eating window.
Another strange things about Ghrelin is that it may rise for reasons other than a need for food. It may be making you hungry in order to get you to take in more salt. Salt has many very critical functions: It’s needed by the heart to pump blood properly, it’s a key component in cell-to-cell communication and the optimal transmission of nerve impulses to and from organs like the heart and brain. Low salt has been shown to stunt growth, increase insulin resistance and increase uric acid levels, stimulating oxidative stress in the mitochondria leading to weight gain. When we intermittently fast, we automatically reduce insulin levels, which as well as being the fat storage hormone is also the sodium uptake hormone. So Fasting leads to a low levels of sodium in the blood which can trigger hunger. The solution: Eat more salt when you are eating.
The standard low sodium guidelines of only 2.3g of sodium per day drastically underestimate how much salt the body really requires for optimal functioning. A study in the New England Journal of Medicine found that an estimated sodium intake between at least 3g and 6g per day was associated with a lower risk of death and cardiovascular events. In fact, actually following the low salt guidelines posed a particularly high risk to health.
Of course one of the greatest health benefits of fasting is lower insulin and blood sugar levels. So lets look at how insulin affects the body and your hunger. When you eat, insulin goes up and insulin helps you utilise carbohydrate for energy or store it as glycogen. This glycogen is stored in the liver or muscle and when they are full any excess is stored as fat. Now, different foods will trigger the release of different amounts of insulin. Fat stimulates a tiny amount of insulin, protein a little bit more and carbs/sugar provoke a large rise in insulin. Then, after about four to six hours after you eat, insulin levels will have gone down, and the glucose level in your blood starts to decrease, this prompts the pancreas to secrete glucagon. Glucagon has the opposite function of insulin. Insulin stores food energy, but glucagon pulls that energy out from your glycogen stores and your fat stores. So if you’re eating every two hours and getting six small meals a day, you never let glucagon do its job and your body never starts burning into your glycogen or your fat stores. Not a good strategy for losing weight. But, what about hunger?
In a study in 1986, it was found that if you inject an animal with insulin, it will eat more. So adding insulin increases appetite. If
you have insulin floating around with no new glucose coming in, your blood glucose will drop, but the insulin doesn’t just go away, it takes time. But with insulin still high the pancreas can’t produce glucagon so we can’t access the stored fat on our bodies. So no access to fuel triggers hunger. Insulin needs to be low for glucagon to use your fat or glycogen stores for energy. Alternatively, studies have shown that giving an animal glucagon, reduced food intake. So glucagon decreases appetite.
So after a meal, if you’re patient and can go without food for more than 4 hours or so, glucagon will allow you to start running on your stored energy and you will be less hungry.
Another aspect of fasting and appetite suppression is the bodies manufacturing and use of ketones for fuel. For the first few hours of a fast the glucagon suppresses hunger and helps you power the body by burning your stored glycogen and fat. Then, as your body starts to run low on glycogen, your body switches over to burning primarily fat for energy and your body starts making ketones. Because even the leanest of bodies has plenty of fat for fuel, Ghrelin is turned right down. With a constant supply of fuel from the body’s fat there is no need to trigger hunger. The little glucose that the body does need is made by the liver.
This is one of the reasons why ketogenic or low carbohydrate diets have such great synergy with intermittent fasting. Lower carb diets keep insulin low and allow you to use more fat for energy, just like fasting will do. It can even be a good idea to start eating like this before you begin intermittent fasting as it will already adapted the body to getting your energy from fat so you’ll have less hunger and adapt to intermittent fasting easier.
So while intermittent fasting is hard for the first couple of days, it’s helpful to know that your body and hormones are working in your favour, making it easier and easier as the days go by. And, if you get enough salt and minerals, avoid diet drinks, eat moderate levels of protein and keep those carbohydrates low then you can make the whole process much smoother.