Is fasting just a fad? What if you don't need to lose weight? We look at insulin resistance and break down the jargon - 5:2, fast 800 and TRE!
Fasting is not new, it has been commonly done as a form of purification in a religious setting but recent studies are shedding light on how it actually works.
When you fast, your body saves energy by recycling old or damaged cells and switches to burning fat. When you break your fast, your body responds like the desert after rain. It starts creating new white blood cells and may help reset the immune system.
When the brain is using fat as fuel instead of glucose, it also secretes BDNF (brain-derived neurotrophic factor), which is thought to prevent dementia by strengthening neural connections and increasing the production of new neurons.
Regular fasting helps to improve insulin resistance and lowers blood sugar. Insulin resistance is when your muscles and liver become less sensitive to the release of insulin (see above). When this happens, your pancreas is working harder, you start storing fat around your organs instead of the usual places and yet you still feel hungry all the time.
Dr Michael Mosley says: "It's as if you're constantly pouring money into your bank account, and then finding it incredibly hard to get it out again. High levels of insulin prevent your body from accessing and burning its energy supply."
I've been a fan of Dr Mosley's books and TV shows as the advice seems sensible and backed up by research (both proper trials and testing on himself!) He has popularised several diets based on fasting:
If that was confusing, here's the take-home message...
If you are at a healthy weight, some fasting may still benefit you. The easiest way to do it is by time-restricted eating, for example, have an early dinner and not snack after that.
If you are looking to eat more healthily, low-carb with adequate protein and fat is the most sustainable and tastiest way to go.
If you are healthy but want to lose some weight, have clear goals and restock your fridge and pantry with alternatives that you can eat safely. You can experiment with the 5:2, fast 800 or any other combination along with increasing your exercise.
Fast-paced exercise e.g. 3 bursts of 10 minute brisk walking versus 10000 steps a day is easier to do and to stick with long term.
Getting enough sleep is also key to having fewer food cravings in the day.
If you have a health condition or are pre-diabetic, please seek medical advice or inform your health professional before starting on any diet.