Dr Eric Pugliesi
Fasting, is one of the most ancient and widespread healing modalities in the world. Hippocrates of Kos recommended the abstinence of food and drink for patients who showed symptoms of illness in 460 BC. Recently, Intermittent fasting is gaining interest because of its metabolic benefits. Among them, the metabolic switching hypothesis.
A good starting point is to understand how food is absorbed and utilised. The food we eat is broken down into particles that get absorbed by our gut and are then transferred up as molecules to our bloodstream. Among these particles are the macronutrients we have spoken about on our previous blogs: carbohydrates, fats and proteins. Carbs, also known as starches are quickly broken down into sugar and transferred into our cells for quick energy. Our body has learn to be energy efficient and has the option of storing some of our carb intake in muscle tissue. If there is any remaining sugars we can transform these into fat (this is our reserve tank). But sugar can only enter our cells with insulin, a hormone made in the pancreas. Insulin brings sugar into the fat cells and keeps it there. Between meals, as long as we don’t snack, our insulin levels will go down and our fat cells can then release their stored sugar, to be used as energy. We lose weight if we let our insulin levels go down. The idea of IF is simple, if we have episodes of fasting we will use our reserve storage (fat deposits) and rely less in our quick fuel…carbs.
There are different modalities of IF. We will focus on the 2 that are the most practical and sustainable.
One of the most common methods if called daily 16:8 Intermittent Fasting. 16:8 IF involves eating only during an eight-hour window during the day and fasting for the remaining 16 hours (eat between 7 am to 3 pm, or even 10 am to 6 pm) This option seems to be the easiest to adapt and can be used as a weight maintenance modality.
A second modality is Dr Michael Mosley’s preference, the 5:2 approach. This option involves eating healthy 5 days a week. For the other 2 days, you limit yourself to 500-600 calories/per day. This method allows one to sustain the habit by going through cycles of fasts within a week.
Fasting is evolutionarily embedded within our physiology and the process of switching from a sugar fuel to fat-derived ketone one is called keto-adaptation. It can take 2-4 weeks before you adapt to these new eating modality. You may experience hunger or crankiness whilst you adjust. If you persevere, the fat burning process will naturally assist you by decreasing your appetite.
If you want to excel in your fasting trial it is best to combine the IF approach that best suits your lifestyle to the following:
Avoid processed sugars and refined grains. Instead, eat fruits, vegetables, beans, lentils, whole grains, lean proteins, and healthy fats (a sensible, plant-based, Mediterranean-style diet).
Let your body burn fat between meals. Don’t snack. Be active throughout your day. Build muscle.
It is important to check with your doctor before you start intermittent fasting. Once you get the go-ahead, the actual practice is simple and intuitive.