The premise behind intermittent fasting from my Dietitian and Fitness Model perspective is that it can assist in fat loss by shocking the body and thus breaking through a plateau in aesthetic results.
The idea is that your body gets into a routine and pattern and even though it may be a healthy routine we require a shock to this to continually create greater results. It’s rather exciting that we can manipulate the TIMING of our meal and snack intake to force further fat loss. One example is to choose to skip Breakfast twice a week to force the body to burn into its stubborn fat stores to find the energy that it usually gets from that breakfast meal each day. It’s expecting those calories and then when you don’t give them to your body it has to go looking for energy from fat stores.
It doesn’t have to be Breakfast that is fasted, it could be any meal or snack in the day or perhaps a fast all morning but the trick is to not make intermittent fasting the new ‘norm’ for the body because then it can go into a storage mode and slow down metabolism; whereby we start holding onto our calories from our meals because the body does not know when the next intake will be and somewhat prepares for a fast, which is unhealthy. Thus Intermittent fasting should only be ‘intermittent’ in nature meaning occasionally and not for too long.
The 5:2 type of intermittent fasting means for two days you reduce your daily calorie intake substantially usually skipping a meal and a couple snacks practising the typical intermittent fasting technique and then for the remaining five days of the week you revert back to normal eating patterns. The time clock approach or 8 hour window of eating simply means eating breakfast a little later and having dinner a little earlier in order to create a longer fast throughout the night.
Any technique of intermittent fasting can work for fat loss, the key is to remember it’s only intermittent so don’t make it the new norm. The concept of delaying or skipping breakfast occasionally can shock the body and the notion of having an earlier dinner can be helpful to prevent you from going to bed with a full stomach of excess energy that can store as a fat overnight. The downfalls can include over eating of portion sizes following the fast; this can be quite common as your body may wish to binge as the appetite gets too much, so we need to be very conscious of this. Also, as mentioned there is the risk of IF slowing metabolism rather than speeding it up if we over do the fast for too long a time span or make it the new norm, keep it short and infrequent to shock the body.