If you are on Intermittent Fasting you are burning fat. The same chart from before shows why.
Carbs pass through quickly, Protein less intense but longer and Fat even longer. But what is the significance of the vertical (height) of the curve? Let’s add another line to the graph to try and explain.
What is missing from the chart is scale on the time axis. The red line shows the energy needs of your body. If your energy input is greater than you energy needs then the body stores that energy. If your energy input is less than your body needs the body releases that energy.
In the chart above calories consumed as carbohydrates are consumed quickly but get stored in the body since they exceed the need of the body for energy. Protein is the same, but much less. Fat is below the curve. This is why the Low Carb High Fat diet works so well.
Dr Fung describes the means of storage as being in one of two compartments. There’s a short term storage (the refrigerator) andd a deeper term storage (the basement freezer). The body can more easily access the short term storage. To move from the shorter term to the longer term requires fasting.
This points out what’s the problem is with just Low Carb High Fat as a means of dieting. If you don’t do intermittent fasting you are only getting the benefit of the dinner to breakfast fast.
If you ate breakfast at 8 AM, lunch at noon and dinner at 6 PM you are keeping the energy level up with food you eat for 10 hours of the 24 hours. Worst than that the 10 hours is extended by the time if takes to digest the food from dinner. If it was a largely carb meal then it might be a few hours until you go to consuming what you stored in excess during the day. Your fasting might only be 8 hours and you spend most of that time working off the day’s excess.
Is there a simple mathematical model for this? Should be easy enough to figure out one and then calibrate it for a particular person. Two of the curves are parabolic or could be simulated with a sine wave.