Intermittent Fasting and Fat Loss

What is it?

I’m sure many of you with any sort of interest in health and fitness have stumbled across this term. Intermittent fasting refers to intermittent (sporadic and not continuous) bouts of fasting (not eating) and has been shown to improve many health indicators such as improved insulin resistance, decreased body fat levels, improved glucose metabolism and lower blood sugar. Plenty of research is being done confirming that refraining from “grazing” on food all day is a very simple approach to obtaining many of the health benefits associated with exercise and diet.

Body Fat and its Origin

One of the most valuable improvements that can be had from exercise and diet is improving insulin sensitivity. This is the ability of the cell to respond to insulin by allowing glucose to enter the cell to be metabolized into usable energy. What scientists have found is that many people in Western society have compromised the cells ability to receive and metabolize sugar due to traditional western diets. When high amounts of sugar builds up in the blood stream after eating, insulin is unable to transport all of the sugar into lean tissue to be metabolized. The excess glucose must go somewhere so adipose tissue (body fat) welcomes it with open arms for later use. As the cells of lean tissue, such as muscle, become insulin resistant, fat cells become insulin “sensitive”. Simply put, the muscle cells shut their doors and block sugar from coming in and the fat cells build more doors and leave them wide open and welcome the glucose in. This is when your fat cells begin to swell and you are left with unsightly body fat.

Now, let’s take a biological perspective on what body fat actually is. I recently asked a friend of mine who was taking a health and wellness course in college what body fat was; they did not know. I am assuming that many people do not actually understand the purpose of body fat and simply think it is just an eyesore with no purpose. To put it lightly, body fat is the reason we are alive today. In times of food scarcity, the energy stored in our body fat provided us with the energy to hunt and gather until we found food again. If we were unable to store body fat, we would have burnt through the glucose in our muscles very quickly and we would have died without constant intake of food. Evolutionarily, those species which were able to consume as much as they possibly could when they found food and store the excess as body fat for later use lived to pass those genes on. Those who couldn’t store fat died off. That is why we are all left with the ability to store fat relatively easily. If we couldn’t, we never would have survived a single winter.

That explanation leaves us with the clearly obviously solution to burning off excess body fat; eat less. Unfortunately due to the abuse our metabolisms may have taken from eating a western diet, it isn’t that simple anymore. Back when we were required to expend energy to find our food we remained insulin sensitive. Now that refined sugary foods are available to us immediately and on a constant basis, the overconsumption has dismantled our body’s ability to tap into its fat stores and use fat for energy.

How Intermittent Fasting Helps

It is now clear what must be done to repair the ability of our body to tap into stored fat; improve insulin sensitivity. Emptying the muscle cell of its glucose is a great way to do this. Once the cell is emptied of its glucose, it is starving for more. The muscle cell will up-regulate insulin receptors (open its doors) and down regulate insulin receptors on the fat cell (close its doors) so the glucose we consume can be restored into lean tissue. Over time, this will result in more energy from food going into lean tissue and less becoming stored as body fat resulting in weight loss.

How do you empty the cells of its glucose? One way is to exercise… HARD. Walking at a slow pace with low intensity does not provide a muscle contraction intense enough to use a meaningful amount of glucose. This is why almost everybody who walks to lose weight does not lose weight. Proper weight training or HIIT (high intensity interval training, such as sprints) is a terrific way to empty the glucose reservoir.

The easiest way to use up glucose is through intermittent fasting. According to Dr. Mark Mattson, leading expert in intermittent fasting, it takes at least 10 hours for most people to empty their glycogen (glucose) stores without exercise. While you are sleeping you are in a fasted state. But, what do most people do right when they wake up? They break their fast by eating breakfast… get where the name comes from? A great approach to intermittent fasting is simply skipping breakfast. If you sleep for 8 hours and wake up at 6am and hold off until noon to eat lunch, you have fasted for 16 hours! Then go about the rest of your day avoiding foods the decrease insulin sensitivity (refined grains, sugar) and you are well on your way to losing body fat.

Another approach, if you cannot give up breakfast, is to practice “time restricted eating”. This means that you only allow a certain time period during your day where eating is allowed, such as 8-10 hours while you are awake. For example, eat breakfast at 8am, dinner at 5:30pm and refrain from consuming any food after 6pm. A recent study showed that the group who restricted their eating time to 8-10 hours improved insulin sensitivity and lost body fat in comparison to the opposing group who was able to eat whenever they chose during a 24 hour time period. What is amazing is that both groups ate the same approximate the same amount of calories! (Chung, H.)

Remember, this is a slow process. It takes more than just a couple of weeks to make noticeable changes in fast loss so stick with it! Give it a 6 week trial and combine your intermittent fasting efforts with High Intensity Strength Training and you will be well on your way to a better physique and a healthier body!

(Chung, H., Chou, W., Sears, D. D., Patterson, R. E., Webster, N. J., & Ellies, L. G. (2016). Time-restricted feeding improves insulin resistance and hepatic steatosis in a mouse model of postmenopausal obesity. 1743–1754.)

Mattson, M. P., Longo, V. D., & Harvie, M. (2016). Impact of intermittent fasting on health and disease processes. .