My absolute focus is getting evidence-based body results with added benefits for health and longevity. This has led to me building my entire nutrition practice around two key subjects - fasting and gut health. This blog will talk about 16/8 intermittent fasting. You will have heard of 5:2 diet, a weight loss methodology based on intermittent fasting. I get consistently better results for my clients - and myself - with the 16/8 approach where you watch the clock, not the calories. So let me talk you through how it works and why it works.
In simplest terms what you need to do is widen the gap between meals to allow your body to tap into fat reserves more easily. So, 16 and 8 refer to hours of fasting and non-fasting with a day. Typically this means finishing dinner at 8pm and not eating until 12 noon the next day however some people choose to stop eating at 4pm and have breakfast as normal the next day.
16/8 is the only fasting method that doesn’t require calorie counting. For those who struggle with the dieting mentality, or for people who struggle to get by on just 500-600 calories in a day as per the 5:2 fast diet, it seems an altogether simpler approach.
Your metabolism won't plummet if you skip breakfast. Research on fasting seems to show that eating less often, like the 16/8, could actually boost your metabolic rate. In one study, conducted at the University of Nottingham, a two-day long fast boosted resting metabolic rate by 3.6%. It may sound marginal but in many ways, weight loss is ‘won’ through an accumulation of these “marginal gains”.
As explained in my book, Eat, Fast, Slim there are many other tips to make fasting even more effective such as short bursts of HIIT (high intensity interval training) during the fasting window, ensuring your first meal of the day is warm and protein-rich, and for women skipping fasting as you approach menstruation. For those really focused on shifting the pounds fast, around 6 days a week following this 16/8 protocol is ideal, whereas for maintaining that lean look, around 2-3 of days a week is about right.
Why the 16/8 fasting approach can also slower ageing
Midlife has turned my focus to really researching the whole subject of ageing. Adding years to life and life to years is a great motivation.
It boils down to this. You are as young or as old as your smallest vital links - your cells. Ageing begins when your normal process of cell regeneration and rebuilding slows down. At a cellular level, the hormone insulin-like growth factor (IGF-1) has both positive and negative effects. Like insulin, it is anabolic, meaning that in effect it tells our cells to grow and multiply.
If IGF-1 is kept high, our cells are constantly dividing and multiplying which is good if we are trying to build big muscles and not so good if those cells become damaged and cancerous. High levels of IGF-1 have been linked to prostate cancer and postmenopausal breast cancer. When IGF-1 levels drop, the body slows production of new cells and starts repairing old ones - DNA damage is more likely to be permanent.
What does all this mean for adding years to our life? Headed by gerontologist Valter Longo, researchers at the University of Southern California, have focused for the last decade on the effect of caloric restriction on the functioning of cells. When Longo and his researchers began exploring the links between food intake and longevity, research on mice found that restricting calories extended lifespan by up to 40%. Genetically engineering the mice to have low levels of IGF-1 did the same thing.
Other research on our monkey cousins has shown that, in most cases, both calorie restriction and intermittent fasting helps them to live longer. In fact, it appears that the more they fast and the less they eat, the longer they live. Sounds crazy, doesn’t it? After all, we’re much more used to hearing ourselves say we’re going to “starve to death” or that we’ll “waste away” if we go a few hours without a decent meal!
Lower levels of IGF-1 work for people too. During the Great Depression, there were food shortages and drought yet life expectancy actually rose by six years between 1929 and 1933. Intrepid scientists have also found remote populations of people where the rules of ageing do not apply. Settlers in a remote region of Ecuador who have low levels of IGF-1 seem to be ‘immune’ to diabetes and cancer, despite having very unhealthy lifestyle.
In fact, the only way you can naturally reduce levels of IGF-1 these days is by choosing to fast, rather than waiting for life to force it upon you. The benefits come quickly though. Within just 24 hours of fasting, IGF-1 falls.
Fasting and lowering inflammation
Inflammation is the body’s normal response to injury, aimed at removing whatever is causing the injury and kick-starting the healing process. Too much inflammation can obviously be dangerous, as is the case in inflammatory conditions such as arthritis, atherosclerosis and even eczema. If you or someone you know has a condition that ends in “itis” then it is linked to inflammation.
High levels of body fat are associated with increases in inflammatory markers such as IL-6, TNFa and CRP. Studies on several different fasting formats show that these inflammatory markers tend to reduce during periods of fasting. Intermittent fasting has also been specifically shown to reduce the symptoms of asthma, another condition in which too much inflammation plays a key role.
So, if you want the recipe for effectively fat loss, slower ageing and reducing inflammation, look at adding intermittent fasting to your lifestyle mix.
Last but not least, no health approach is complete without ensuring the health of the microbiome. No matter what your current health status, I strongly recommend spending time nurturing gut health as detailed in my Gut Plan Diet