Our grandparents were natural intermittent fasters - now it's the new diet craze
Rich butter, creamy milk, bread and potatoes - we often look back at what previous generations ate and wonder how their waistlines could have stayed so trim.
But, unbeknownst to them, our grandparents were following a basic principle in the fight against fat - by not eating late at night.
Now the whole diet world is exhorting the virtues of 'intermittent fasting' with celebrities including Hugh Jackman, Beyonce, Tom Hardy and Ben Affleck swearing by it for its amazing benefits and ease of execution.
One of Ireland's best-known fitness coaches, Pat Divilly, has been a fan of the approach for the past six years.
Speaking to the Sunday Independent, ahead of his appearance at Vitality Expo 2018, Pat Divilly said: "We used to eat our three square meals a day. Maybe a snack at some point. But in the last 30 years, with the age of convenience foods, we always have food at our finger tips so snacking has just become 'the done thing'. Whereas our grandparents had their three square meals a day, full of nutrient-dense food."
Mr Divilly says one of the benefits of intermittent fasting is that it brings us back to craving wholefoods rather than the convenient quick fix.
"It's amazing," he said. "My experience of it is that you tend to crave real food by the end of every fast. When you give your body a break from digestion and allow your hormones to settle to where they are meant to be - rather than opting for sugar spikes - then your body will innately know what it wants and you will always end up reaching for wholefoods."
The diet works by encouraging people to follow a timed eating pattern so they can consume their favourite foods and still manage to lose weight.
Advocates typically eat between an eight-hour window during the day (usually 10am to 6pm), leaving 16 hours of fasting at night - most of which time you spend asleep .
Mr Divilly says one of the benefits of the approach is that "it promotes black-and-white thinking".
"There are no grey lines," he says. "The way I would describe it is like this: if someone goes out on a night out and says 'oh, I probably won't drink tonight', they will probably end up having a few glasses of wine. Whereas if someone says 'I don't drink', it's a very solid resolution.
"It's like someone who is vegan. They don't have to fight with themselves about it when they are looking at the menu, they know they just don't eat meat any more."
Research has shown how, during the 16-hour fast, the body undergoes a change that gives the person the extra advantage against someone who doesn't give their digestive system a break.
Here's how it works: when you eat, you store some of that energy in the liver as glycogen. After 10 to 12 hours of not eating, those reserves are extremely low (giving you an irritable 'hangry' feeling). However, with little glycogen left, fat is released into your bloodstream. Your fat cells head straight to the liver where they are converted into energy for your brain and body, so you are literally burning fat to stay alive.
Intermittent fasting was first used by doctors in the early 1900s to treat various disorders such as diabetes, obesity and epilepsy because it stabilises blood sugar levels and induces cellular repair processes.
Pat Divilly is taking part in Vitality Expo 2018, Ireland's largest natural health and well-being show, on September 8-9 in the RDS in Dublin. He will be joined by some of Ireland's best-known speakers, including Patrick Holford, Alison Canavan, Paul Byrne and the Happy Pear.
Tickets start at 8 euros. For more information log on to www.vitalityexpo.ie