Hi paleo:

You must understand that just doing 16:8 does not put you on a weight loss diet. A person can easily eat two, even three times their TDEE in an 8 hour period. If they eat any calories over their TDEE, they gain weight. Just eating 100 calories over your TDEE each day will cause you to gain over 10 pounds a year! You really need to understand TDEE – it works for any diet, not just 5:2 – so I suggest you read this explanation: https://thefastdiet.co.uk/forums/topic/tdee-for-the-curious-or-why-dont-i-lose-weight-faster/

Just figure out an estimate of your TDEE by using the calculator at the top of the page under ‘How It Works’ and keep track of the calories you are eating for a week or so. You don’t have to do it forever. But doing it for a short time will probably educate you on how many calories are in the foods you are eating and how many calories you are eating overall. When you compare the number of calories you are eating to your TDEE number, you will have a good idea of why you might have been gaining weight, and what you have to do to lose weight.

Good Luck!

Hi paleo:

I’m not sure from your comments whether or not you understand that you must eat less than your TDEE to lose weight. Just eating all of your food in an 8 hour period and ‘fasting’ for 16 hours will not automatically cause weight or fat loss. That is because if you eat over your TDEE, any small amount of fat you might burn by fasting 16 instead of 12 hours will be replaced by the excess (over TDEE) calories you are eating during your 8 hour eating window. If you eat your TDEE on the button each day (impossible), again, you will not lose weight and any fat you lose will be negligible.

Good Luck!

Hi paleo:

Again, you seem to misunderstand my position.

If you eat under your TDEE over the period of a week, whether or not you eat under your TDEE daily or on some days and not others, you will lose weight. If you do, GREAT! How much you will lose will depend on how far under your TDEE you are eating, so if you don’t lose fast enough, just eat less and you will lose faster.

I have nothing against an every day reduced calorie diet. They have worked for millions of people for a long, long time.

Good Luck!

Hi Paleo,

There are benefits to be had by doing 16:8 but like Sim said if you eat over your TDEE then you are fooling yourself thinking 16:8 will add any value. Unless you are lean it is very likely that your glycogen stores (in your liver and muscles) are fully topped up. They will NOT be depleted within a 16 hour “fast” period. An overweight person will easily have enough stored glycogen (stored version of glucose) to last 48 if not 60 hours. When I first started 5:2 I would water fast for two consecutive days, a total of 60 hours. I would just be entering ketosis by the end of 60 hours. Not 16 hours!! Im now in maintenance mode and still water fast for one day (36 hours). Im 71kg and my BMI is 22.4. I now enter ketosis after 24 hours. I measure this with a glucose/keto meter (as used by diabetics). I suppose it would be possible to get into ketosis within 16 hours if you lived on a very strict keto diet and were quite slim and physically active. Otherwise Id have to say not possible. By all means do 16:8 but make sure you stay below your TDEE. Hope that helps.

For me 16/8 has no effect in losing weight. Neither 20/4. Because I do not count calories and eat according to my hunger, even with only 2 meals a day I “manage” to eat around my TDEE and don’t lose weight. In the last month I’ve added 23/1 in equation, but it’s too soon to say that I could keep it long term.

So yes.. it’s like you said, test it until you find what works for you. Good luck!

Hello Paleo, I’m a new faster. I also fast for 16 hours three or four days a week after my final evening meal and I rarely go much longer. Dr Mosley picked 5:2 because it suited him and I think there’s room for flexibility if what your doing’s working. I went low-carb 18 months ago and the increase in natural fat in my diet means that I’m rarely hungry and usually eat just two meals a day. In addition, I drink coconut oil and it seems to surpress appetite in addition to its other possible benefits. Without hunger I easily lost about 10 pounds in weight after I mostly dumped carbs and I believe I’m at my natural weight. Indeed, I don’t want to lose any more weight.

So, are you trying to lose weight? If so, a lower-carb, higher fat approach works for most people. I do not count calories at all. For me, it’s a pain, a needless complication and I don’t need to do it. I’ve recently added a 16 hour fast to my low-carb approach to lower insulin, have some ketosis and some of the benefits of fasting. I’ve read that the benefits begin at 11 – 12 hours, so my gains from 16 hours might be modest, but if I continue long term that’s better than being perfect and stopping after a while. Sustainability is better, I think , that obsessive perfection. My approach is disciplined by most people’s standards, but flexible. The important thing is that it works for me.

If you find weekends difficult, how about one slighly longer fast in midweek, then 16 hours most days and give yourself a break at weekends? If you’re eating right, that will make you better than 95-99% of the junk-eating population. Some love rigid perfection, but you’ll have gathered that I’m happy with a more relaxed and flexible approach. Best wishes.

i planned to fat always 24 hours and water only. i just did my first one and it was just that. had a piadina thick with nutella with a cuppa after, then some chips and a few kiwis, really nice x

Dude, you need to understand the science behind fasting, else you will always be in doubt. I would suggest to check out The complete guide to fasting by Jason Fung.

Thank Paleo,
I read the link and am converted, on my fast days I’ve been eating breakfast but will stop doing that and incorporate the 16:8 IF pattern into my timetable, it makes sense to do it every day on fast and non fast days. I am counting calories everyday anyway.
My TDEE as calculated here seems way too high to me- over 2000 calories per day, I’m more comfortable sticking to 1500. Though on fitness pal they calculated 1250 for me. Basically I’m going to juggle around with all of the above!
I can indulge in half a home made pizza tonight for example after my swimming session as it’s Friday and I promised my son pizza and a film!
I’m only 3 weeks in to all this so am still testing the water so to speak and discovering what works best for me. Have already lost 4.3kg (about 9 and a bit pounds)
Like Haifa I’m post menopause so have to factor that in too, but thanks to this encouraging early loss I know that it can be done.
Well done Pollypenny!