As well as offering a fresh approach for people trying to lose weight, IF has been developed by scientists wanting to help people reduce their risk of developing diabetes, dementia and cancer
IF has been most extensively studied in volunteers who are obese or overweight. In a recent study of 115 overweight women, those who restricted their calories two days a week lost more fat and had a greater improvement in biomarkers that relate to breast cancer risk than women doing conventional daily dieting.
The benefits in people who are not overweight are less clear because there have been fewer studies. In one experiment, a number of fit young men were asked to practice IF without losing weight for a few weeks. During that time they saw improved insulin sensitivity, a marker for reduced diabetes risk
Studies of IF in animals have shown that it reduces risk of dementia. Human studies have just started.
Fasting also has a spiritual dimension and has been advocated by most of the great religions
There do seem to be benefits from intermittent fasting which go beyond weight loss, though these benefits have been less studied. We know, for example, that a lot of repair and routine maintenance goes on in the cells when we are not eating
I would suggest reading The Fast Diet as it gives detailed advice on how to prepare yourself before you start. Some people find it surprisingly easy to adjust, others find it quite challenging. Having a fasting buddy and joining a support group really helps. Choose your days – ones in which you are busy, but days that are not too demanding. Ideally have regular fast days. When starting it helps to plan in advance what and when you are going to eat.
In reality a fast day is 36 hours. If you finish your last full evening meal at 7.30pm on Sunday, then Monday is your fast day, you are not going to be eating normally till Tuesday morning 7.30am. That is 36 hours. If you decide instead to fast from 2pm on Monday until 2pm on Tuesday, then that will only be 24 hours. Wait till 7pm and that is 29 hours. To do 36 hours you would have to hold off till 2am on Wednesday, which would be a little inconvenient
There have been different studies using different approaches. People who took part in Dr Krista Varady’s studies of Alternate Day Fasting (ADF) had just one meal a day, at lunchtime. Those who took part in Dr Michelle Harvie’s studies of the 2 Day Diet at several small meals a day. Michael prefers having two meals a day, breakfast and an evening meal. Mimi prefers several small meals. Which approach is better? The one you can stick to. Some people find, for example, that eating breakfast actually makes them feel hungrier later in the morning.
The Fast Diet book contains lots of recipes, the Fast Diet Recipe book has even more. The basic principle is to eat foods that are high in protein and fibre, as these are the most satiating. That means fish, meat, vegetables.
If you feel you really need the boost, try to avoid easy carbs and go for fresh, raw ingredients if possible such as a handful of almonds, carrot or celery sticks, apple slices with skin. Although there is a danger that I am now sounding like a second hand car salesman, there also lots of suggestions in The Fast Diet Recipe Book.
You can drink anything that has no calories/low calories. This includes coffee and tea. Although I don’t personally drink milk in my tea or coffee on fasting days, I don’t see this as a problem. Milk is generally a healthier drink than, say, orange juice, being rich in protein and relatively low in carbohydrates.
You can, but I don’t recommend it. Alcohol is high in calories and is also likely to produce a spike in insulin. There is plenty of research which suggests that there are significant benefits to having two alcohol free days a week, and so I think it is good idea to have your alcohol free days coincide with your fasting days. I also tend to nibble more when I drink.
There are lots of free calorie counters available online. You could also use the recipes from The Fast Diet and The Fast Diet Cookery Book, which have been carefully balanced and counted. You will gradually develop a sense of roughly how many calories are in a portion, though it is worth intermittently double checking how accurate your calorie counting is.
There is good evidence that people who exercise in the fasted state burn more fat. In one study men who exercised before breakfast burnt more fat than those who exercised afterwards. Exercise can also be a useful distraction if you begin feeling peckish. Don’t, however, attempt to do a lot of endurance training on a fasting day and if you feel uncomfortable, stop.
There is no great rule. I weigh myself a couple of times a week and if I see my weight creeping up use that as a motivation to be a little bit stricter. The reality is that weight tends to change quite a bit across a week, so once a week should be enough to monitor a trend.
Try adding another fast day to make it a 4:3 Fasting pattern as this still allows you some flexibility as to which days to fast.
If you want to lose weight faster, or have hit a plateau with the 4:3 Fast, then you might consider doing Alternate Day Fasting. As the name implies, with ADF you cut your calories to ¼ of their normal level (ie 500 for women, 600 for men), every other day. On your non-fast days you eat normally, though in some trials of ADF the volunteers were allowed to eat what they wanted and still lost weight. Studies on people doing ADF have shown that, on average, they tend to lose around 2lbs a week, most of it fat.
You don’t want to obsess about weight. What you really want to do is lose fat, preferably around the gut. I encourage you, before you start, to measure your girth (around the belly button), and monitor the change over a period of time.
Look at the calories you are getting from drinks on your non fast days. Juices, lattes, alcohol, fizzy drinks, smoothies all contain a lot of calories. If you can move to drinking more water and sugar free tea/coffee that will help. Calories you drink do not satiate. If you eat three apples they will fill you up. Drink 3 apples in form of a small fruit juice and it will not fill you up.
Simply moving more will help. I always take the stairs, even up 7 flights. Get a pedometer. Aim to do 10,000 steps a day. Most people do less than 5000. A long term study on people who lost weight and kept it off found that those who were successful all increased the amounts they walked.
Keep a diary of everything you eat or drink for a week. Then look at the calorie content. Some foods may leap out. I was horrified to discover a muffin can be anywhere between 300-600 calories. Lots of evidence that people who keep an honest diary lose more weight
If you cut your calories 2 days a week, don’t overcompensate on the other days and keep reasonably active then you will lose fat. Unfortunately fat is incredibly energy dense, which is why for some people the process can be frustratingly slow.
I wouldn’t recommend it for children or teenagers, as they are still growing. I don’t think there is evidence of problems in starting later in life, but this is not something I would recommend for the frail elderly.
If it has been a long time since you went for several hours during the day without eating then you may find the first couple of weeks quite tough. People think that after several hours without food they will feel faint because their blood sugar has fallen, but this is a myth. Unless you are a diabetic, your body is extremely good at preserving your blood sugar levels and will do so for many days without food.
This is another very common myth. The initial response of your body to a reduction in calories is to increaseyour metabolic rate. This is because, in our hunter-gatherer past, survival in times of food shortage would have depended on our becoming more active, going out to hunt and look for food. Only under conditions of extreme calorie deprivation, when we have been for weeks without enough food and our body fat has fallen dramatically does the body go into “starvation mode”. IF is not the same as crash dieting. Starvation mode does not happen if you cut your calories for a day!!
Longer term fasting can precipitate gout but this should not occur with intermittent fasting (IF). On the other hand gout is associated with metabolic syndrome (obesity, insulin resistance, high cholesterol, high blood pressure) and 5:2 should help correct metabolic syndrome, partly through weight loss but also by the reduction in insulin levels. In addition IF seems to reduce inflammation.Drink lots of fluid as dehydration will make it worse. Also avoid fructose, ie added sugar.In general reducing purine rich foods can reduce risk of gout ie anchovies, sardines, kidney, liver, Asparagus, Cauliflower, Kidney beans, Lentils, Lima beans, Lobster, Mushrooms, Oatmeal, Peas, Spinach and alcohol.
I usually recommend suspending fasting for a few weeks after a minor op and at probably around 6-8 weeks after a major operation. In general it’s a good idea to maintain a high protein diet to help repair.
In my experience it tends to come naturally. Once you embrace the idea of intermittent fasting you should discover that your taste preferences change, that you have greater control of your cravings and that fear of hunger no longer dominates.
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