Eat Less to Live Longer - The Secret of Longevity
Research is growing on the benefits of fasting and you may have heard the terms ‘Intermittent Fasting’ or ‘Time Restricted Feeding’ (TRF). But what does this mean, and how can it benefit the body?
It is said that the human body is more easily adapted to fasting than it is to regular eating – and looking at our ancestry we know that cavemen could only have eaten fruit when it was in season and meat when they made a kill. In our modern world of food preservation and the ability to transport perishable goods around the globe, not to mention heavily marketed junk foods, we have a huge amount of temptation around us and most of us consider it normal to eat several times a day.
Eating all the time puts an unnatural strain on the body – every time you put something into your mouth the body is required to produce digestive enzymes and undergo the mechanical process of digestion. This requires cellular energy, and continually instructing our body to digest food means this energy cannot be used elsewhere. By changing eating patterns so that food is consumed within a given window of time, the digestive system is given a chance to rest while the body gets on with other essential maintenance.
Studies have shown that animals fed exactly the same diet gained less fat and more muscle when the food was given over a shorter time period. But weight loss is only the start. There is also strong evidence to suggest that regular, controlled periods of fasting increase longevity, improve physical strength and increase resistance to tumours, inflammation and neurological degeneration, such as that seen Parkinson’s, Alzheimer’s and dementia.
How does it work?
Intermittent fasting is different to calorie restriction. It consists of regular, controlled cycles of fasting and re-feeding. During the fasting period the digestive system is inactive, and the body is able to use energy for other processes such as cellular repair and tissue rejuvenation.
The initial benefit of fasting is in fat burning and appetite regulation, but to gain further health benefits the fasting period can be gradually increased up to a 16 hour continuous period. A 16 hour fast means your eating is restricted to an 8 hour window - so for example if you finish your evening meal by 8pm you would not eat again until noon the next day.
- Within 8-12 hours – the liver has used up its glycogen stores, and the body will start to burn fat
- Within 12-14 hours – a process called autophagy kicks in, and your body starts to repair cellular damage
- Within 14-16 hours – the greater benefits of cellular repair and tissue rejuvenation are achieved.
During longer periods of fasting the body goes into starvation mode (which can also be thought of as survival mode) - it seeks out weak, inefficient or damaged cells that it no longer needs and gets rid of them by a process called apoptosis. Think of it as ‘survival of the fittest’. Following the removal of unwanted cells, the re-feeding period gives the body the chance to build new and healthy tissue to replace that which has been destroyed. It is this rejuvenation which is thought to help slow the aging process.
Benefits of fasting
Research is ongoing, but so far the reported benefits of fasting include:
- Improved blood sugar control
- Better appetite control
- Reduced body fat and insulin levels
- Increase in lean muscle tissue
- Reduced inflammation – a key marker of longevity
- Improved detoxification
- Increased energy
- Improved cognitive function and clearer thinking.
How to fast successfully
Start by making a 12 hour overnight fast your norm – this is easy to achieve by simply not eating dinner too late and not snacking before bed, and is probably similar to the way most of us ate as children. Unless there’s a medical reason why you need to eat at a certain time, this really is achievable for anyone. Be sure to drink sufficient water.
Once you feel comfortable with this, it should be possible to extend the fast to 14 or even 16 hours. This probably means not eating breakfast at your normal time, but it is important to distinguish between fasting and skipping meals. The fasting period must be continuous and the idea is not to cut down on calories, although you might find that as your appetite regulates you naturally consume less. In general, you should still consume your normal calorie requirement within your chosen time window. This doesn’t mean bingeing on junk food to get to your 2000 calories – for maximum benefit the calories consumed during the re-feeding period should be good quality ‘nutrient dense’ foods to assist the regeneration of healthy tissue. This is best achieved by avoiding processed foods as far as possible and cooking foods from fresh, in their natural form.
During the fast you should also drink plenty of water. You can have non-caffeinated herbal teas or one cup of black tea of coffee, but over time you should be able to reduce this and still maintain good energy levels. Most people can eventually fast for 14-16 hours with water alone.
What about hunger?
The feeling that most of us perceive as hunger is not truly hunger at all. You might have a feeling of ‘emptiness’ in your stomach which is easy to mistake for hunger - especially when you start out. But if you drink a glass of water and distract your mind with an engaging activity then after an hour or so you should notice that the feeling has not got any worse - and often you will no longer feel hungry at all. If you feel unwell, faint, shaky or nauseous then it is likely that your blood sugar is out of balance, so you may need to start with shorter fasts and build up gradually.
When not to fast
Although fasting can help blood sugar control it is not suitable for diabetics, those with kidney disorders or anyone suffering an eating disorder or other serious medical condition, unless being closely monitored by a medical professional.
There are some concerns that regular intermittent fasting has the potential to disrupt the female hormonal system, so it is recommended that women who are affected start by fasting for shorter periods on 2 or 3 non-consecutive days of the week, adding additional fasting days gradually as the body adapts.
The 5:2 diet has become popular in recent years, particularly for weight loss. This is a slightly different approach where you to eat normally for 5 days a week, and on the other 2 days the diet is restricted to 500-600 calories. This can work for some, but many people find calorie restriction much harder than simply fasting. Fasting is a clear rule that is easy to understand, so there is less room for error.
A fasting mimicking diet (FMD) consists of a very specific, low calorie diet that is consumed for 5 consecutive days, and can be repeated as often as once a month. The diet is very precisely designed, and is high in unsaturated fats but low in carbohydrates and proteins, and this combination stimulates the body to burn stored fat, reduce inflammation and repair damaged tissue. Early indications show that the FMD could help with all manner of health issues from improved cognition to diabetes management.
Longer fasts of 48 hours plus can bring even greater benefits, and are used in specialist hospitals and fasting centres around Europe. However these extended fasts should only be undertaken with the guidance of a Nutritional Therapist or other medical professional who can monitor you closely.
Whatever strategy you choose, the best thing about fasting is that it costs nothing, other than a little willpower!