I have always viewed diets as of little use, reasoning it is simply a matter of calories in and out. I would still think this had I not seen a BBC Horizon documentary on a flight to Australia which to me made sense and which I thought I would try for health and weight loss reasons.
Please note that I make no claims about this being incontrovertible nor scientifically accurate. I am not a qualified nutritionist and I only say it makes sense to me and is working so far. It may not be for you and you may disagree with its validity - in which case ignore all this and don't try it.
There is no point in repeating the scientific points when they are set out in detail in the article link after this sentence. I recommend reading it before you read the rest of this, if only to see that there is credible evidence to support its approach.
http://timesenterprise.com/news/x2056572230/Hunger-games-The-new-science-of-fasting
The key passage for me is this - 'A fast is considered to start about 10 to 12 hours after a meal, when you have used up all the available glucose in your blood and start converting glycogen stored in liver and muscle cells into glucose to use for energy. If the fast continues, there is a gradual move toward breaking down stored body fat, and the liver produces "ketone bodies," short molecules that are by-products of the breakdown of fatty acids.'
A more prosaic comparison that may make sense is this - Imagine the body as an engine with a tank and reserve tank of fuel. The reserve tank is the store of fuel in your fat deposits. As you eat you put fuel into the tank and take it out to fuel your daily activities. If you put in more than you take out it may be stored in the tank but if that is full it goes into your reserve tank which is not one which has an automatically limited capacity. Basically this extra fuel is stored as fat around your body, especially your waist.
Most of the time you are able to function with the tank at various levels and the reserve tank is not needed. However, when the tank is empty your body starts to use fuel from the reserve tank and this is when it takes fuel from your fat stores, which is where the claims for targeted fat loss arise. This is what is said to happen when you get into the later hours of your fast. When you start to eat normally you go back to using the normal tank and so on.
I started using the 5:2 plan eating half the 600 calories on fast days around 7.30 am and waiting until 7.30 pm to eat the rest of the daily intake. This wasn't easy, though I stuck to it through a groaning stomach and uneven moods. It worked and I lost about 1.5 pounds per week but the 2 fast days were an ordeal, though I did get better at coping with them.
I then read further about the relative claimed benefits for a 24 hour fast and what I now use, the 16:8 plan.
I simply couldn't manage a 24 fast but the 16 hour one is far more manageable and for me is easier than the 12 hours during the day fast. With the 16:8 plan the hours of sleep count in the fasting period because whilst you are inactive the body still needs fuel, although less than when active.
Thus to achieve the required 16 hour fast you can simply eat, for example, your last meal at 8.00 pm and do not eat until 12:00 the next day or any variation of that which works with your schedule. The benefits of fasting are increased because the hours without fuel are increased.
Strictly speaking I understand that the 16:8 plan allows you to eat your recommended intake of calories every day whilst still getting the underlying health benefits of fasting which are set out in the above article. However, to lose weight you need to consume fewer calories than are used so I use the 600 calories in the 5:2 diet but consume them in the 8 hour 'eating window' in the 16:8 plan. The other benefit is that you can eat the calories in however many meals you want during that window so if you want you can eat four small meals which makes you feel less hungry. You can use a higher figure if you cannot exist on that number and still lose weight, though it will be more slowly.
I also understand that the 16:8 plan is supposed to be a daily plan but I have found that I can eat normally on some days - i.e. have breakfast and eat sensibly throughout the day, provided I stick to the 16 hour fast 8 hour eating window on 2 days each week. What I have found is that having breakfast is to some extent a programmed activity and when you break it the normal urge to eat when you wake goes. Some days I eat breakfast and other I don't and of course not on the fast days.
On the 5:2 plan they say you can eat what you want on the other days even over your normal intake but that the average person only does so by an extra 10%, which still gives the benefits including weight loss. Whilst some days I do this more often than not I don't and for a number of reasons.
When you are limited to 600 calories you get to know the exact calorific value of most foods and when you eat normally you are aware that some foods have huge numbers of calories and by simply choosing alternatives that you like you are consuming fewer calories. More often than not the alternatives are healthier. Also, you have to be creative in your cooking when eating only 600 calories and this changes the way you cook ordinarily. What also undoubtedly happens is that your palate changes - for example things like beans, pulses, even most vegetables didn't feature high on my 'like' list but they do now, provided they are cooked creatively. The key, for me, to taste is in the way food are seasoned and spiced and simple foods can be transformed with a bit of effort.
It does require effort to use the plan and at the start a lot of it. However, it does become much easier, though not effort-free, and after a couple of months I am finding it much easier. I now don't get too hung up if I am a few calories over a target because that just creates stress. If there is a day where I just cannot manage, for example when I get an unexpected invite to a dinner or to have a drink, I abandon that day. The main thing is not to lose the habit and give up all together; I see this as a permanent shift in eating habits not a fad.
When I get to my target weight I will go back to eating normally and using the 16:8 routine several times a week.
You may ask about exercising on fast days. This is possible but I would either do some less strenuous activity like yoga or a short intense session of about 30 minutes; I wouldn't recommend doing a long bout of cardio exercise on the fast days. Ironically, the latter stage of a fast seems to give me a temporary energy boost.
Finally, if this is an issue, the plan means that your food bill is reduced, not just because you eat less but because many of the ingredients you use, and get to like as staple foods when you eat normally, are cheaper. I recommend getting the 5:2 diet plan recipe book to help you make low calorie dishes, some of which I and my family have found are genuinely tasty and which you will want to eat on normal days because they are really rather good.
