The FastDay Forum

Just started on this diet, and have a question that I havent been able to find an answer to.

What is the most optimal fasting day.

36 hours with 600 kcal or 24 hours with 0 kcal?

At the moment im doing one of each

Hi docfons,

Welcome to the forum. I can't answer your question with any certainty, but thinking about it I do pretty much a combination of both and I think a lot of others do to - I don't eat on a fast day until dinner, and that's between 22 and 24 hours after my previous meal of dinner the night before. I then eat up to 500 cals and carry on fasting until the next morning, making 36 hours total on 500 cals including a 22+ hour fasting period.
I think @Carorees did look into fasting periods and found that longer fasts give better results, try looking under the topic about average weight loss being 1 pound a week?

Good luck!

Michael Mosleys 5:2 "diet" is 500 or 600 calories in a 36 hour period. I do the same as Nicky, save my 500 cals until dinner.

[carorees]

Hi @docfons and welcome

As to what fasting method is best - no-one knows! There has not been anything like enough research into intermittent fasting to know what is best.

The answer will probably depend on what you are trying to achieve: health benefits or weight loss. It may also depend on what you eat when you have your 600 kcal. Most of the benefits of fasting come from the fact that when you are fasting you are not eating any carbohydrates which allows insulin levels to fall. (The metabolic changes that take place during fasting have been shown to be identical to those that occur when carbohydrates are eliminated from the diet). The drop in insulin levels helps to reduce insulin resistance (a key metabolic derangement that occurs in many diseases, notably type 2 diabetes and cardiovascular disease) and allows fat release from fat stores. If your 600 kcal has a lot of carbohydrates this will stimulate some insulin release. If you spread you carbohydrate calories out over the day this will tend to prevent insulin from falling as much as it would do if you did not eat until the end of the day or if you did not eat any carbs.

If you are primarily interested in weight loss: our survey of people following 5:2 found the following factors appeared to have an important influence on weight loss: length of the fast (people who had no calories at all for 24 hours or more lost weight faster than those who only fasted for 12 hours before eating something), the amount and composition of food on non-fast days (people whose diet became more healthy - which we defined as more vegetables, less sugar foods and drinks & less ready made meals - lost weight faster than those whose eating habits did not change; while those who found their appetite had decreased so they ate less on non-fast days also lost weight faster) and bingeing (people who binge often on non-fast days lose weight slower).
You can see the paper that we wrote reporting on the statistical analysis of the results of our survey here: https://www.academia.edu/5360346/Factor ... l_analysis

However, having said all of that, I believe that the best fasting method is the one that you can keep doing for the foreseeable future! If you cannot keep going with it then you won't keep any of the benefits you gained. So, really, just go with whatever suits you!

However, having said all of that, I believe that the best fasting method is the one that you can keep doing for the foreseeable future! If you cannot keep going with it then you won't keep any of the benefits you gained. So, really, just go with whatever suits you!

Well said. For me 36h/0kcal (or negligble cals from green tea/diet soda) works great, though I've only recently switched to that from 36/600 (in the last 2 months or so) as I'm so used to fast days now and don't feel I need a small meal.

My understanding from Dr Varady's writing is that, theoretically, longer fasts are better vis-a-vis health benefits and weight loss, but not recommended to start out with as the groups doing total fast, as opposed to 1 small meal, had higher drop out rates.

TedE