Intermittent Fasting

Intermittent Fasting
In this episode of Lifestyle Matters.

Benjamin Franklin said that "The best of all medicines are resting and fasting" and we know today that his words have been supported by scientific evidence. Intermittent fasting has been found to reverse early Type 2 diabetes.

The concept of fasting is not new to many especially if we look at the various cultures and religions around the world e.g., Muslims fast during Ramadan, or the various fasts practiced by Hindus and Buddhists. Even Greek philosophers such as Hippocrates and Aristotle have prescribed fasting for various ailments. This week, we look at how and why intermittent fasting works.

We must first understand what happens during the fed and fasted state. When we eat – (predominantly) carbohydrates get broken down into simple sugar molecules. This triggers an insulin response which promotes the uptake of sugar into our cells. Extra sugar (glucose) gets stored in our muscle and fat as glycogen. Leptin levels (which is our satiety hormone) also increases.

When we fast, glucose and insulin levels reduce. This causes our body to search for an alternate source of energy hence processes such as lipolysis and gluconeogenesis begins.
Later on, ketogenesis occurs whereby ketones are produced from the breakdown of fatty acids which is then used a source of energy i.e. 'the super fuel'

When we fast for prolonged periods of time, our body enters a state of stress adaption whereby it begins certain processes such as cleaning and repairing e.g. DNA repair, protein quality control, increasing expression of anti-oxidant defences etc. As the body enters a fed state, tissue growth and plasticity then begin. However, when we eat 'normally' we do not allow our body to switch from a fed to fasting state. Several evidence have pointed the benefits of allowing our body to go through this metabolic switch and these range from:

• Neurodegenerative health: Potentially reducing the risk of dementia as there is an increase in brain derived neurotrophic factor, increased GABA sensitivity etc.
• Improved heart disease profile: Increases HDL (good cholesterol) reduces LDL (bad cholesterol), reduces resting heart rate and blood pressure.
• Reduces risk of diabetes: Reduced insulin resistance as adiponectin levels are increased and leptin levels reduced
• Reduces cancer growth: Mainly documented in glioblastoma multiforme which is an aggressive type of brain tumor, but other cancers are being studied too e.g. breast, ovarian, prostate.

While most studies have been carried out on animals, there are several others underway involving humans. We have observed over time that the profound benefit of this diet is the metabolic switch that occurs and the benefits we can gain from it whether or not there has been weight loss!

It is important to note that this diet is reasonably sustainable and allows us to eat foods we enjoy in moderation. However, no diet is superior if it is not one that suits our lifestyle, and we must always remember that exercise augments the benefits of any diet we follow.

Author: Dr Saveena Nithiananthan
MBBS, FRACGP, IBLM
Savena is a General Practitioner, Medical Educator and member of the International Board of Lifestyle Medicine