How Effective is Intermittent Fasting for Weight Loss?

March 1, 2020   13 Comments

How effective is intermittent fasting for weight loss? First, we need to define “intermittent fasting”.

How Effective is Intermittent Fasting for Weight Loss?

Is it when I make it from breakfast to lunch without a snack? or when I sleep? The concept is different than simply “fasting” which usually means you go 24 hours without eating.

When I wrote what is the best diet to lose weight?, Shonda replied with her advice.

From Shonda:

It's not a diet, but lifestyle: intermittent fasting. Fast 16 , eat during 8. It's called 16:8. In the fasting drink lots of water and exercise. In eating eat like you mentioned (the Mediterranean diet) above. You are giving your body a break from digestion and giving a chance to burn fat.

I had not been introduced to 16:8 intermittent fasting and I thought it sounding like a good idea. For example, you stop eating at 7 PM and do not start again until 11 AM the next day. You eat from 11AM to 7 PM (and then stop again).

Before I go any farther, I want to emphasize that for those of you who have trouble with eating (such as an eating disorder), I don’t thing this is for you. Snack Girl has readers who are trying to develop a healthy relationship with food and some of them aren’t eating enough.

Intermittent fasting is another way to limit calories but I don’t think that the message “don’t eat for 16 hours” works for those of us who (for example) fear eating.

For those of us who have a healthy relationship to food (perhaps love it too much) and want to try something new - intermittent fasting has a basis in science. Back in the olden days, we didn’t have fridges or Wendy’s so our bodies spent a lot of time not eating.

It may be that our metabolisms are built for this long fast interval and we end up healthier by not eating for 16 hours.

From Harvard Intermittent Fasting Update Article:

Between meals, as long as we don’t snack, our insulin levels will go down and our fat cells can then release their stored sugar, to be used as energy. We lose weight if we let our insulin levels go down. The entire idea of intermittent fasting is to allow the insulin levels to go down far enough and for long enough that we burn off our fat.

In one study after five weeks of 16:8, obese participants ended up with significantly lower blood pressure and improved insulin sensitivity (but they did not lose weight).

What I like about this 16:8 intermittent fasting plan is that is far simpler than what I outline in my Weight Watchers 2020 review. You eat healthy during the eight hours, take a break from eating, and get your fat burning metabolism going with not eating.

Obviously, if you stuff your face with fast food during the eight hours, you will defeat the purpose of the fast. You still have to pay attention to what you eat.

I am worried that you would end up like this guy if you didn’t eat for 16 hours.


Yes, I am sure I would be standing at my fridge at 10:50 AM waiting for 11 AM if I tried intermittent fasting. Also, I am sure my husband would start to demand that I eat (as I would be a wee bit grumpy :)

Whenever studies are done on intermittent fasting, it takes four weeks to see an effect so you must be devoted to it. This is not a quick fix!

I do have a rule about never eating after 7 pm that I stick to pretty religiously. Snacking or eating at nighttime is related to obesity so keep that in mind if you want to shift (but not stop eating for 16 hours).

Have you tried intermittent fasting? How effective is intermittent fasting for weight loss?

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I started the 16:8 fasting about 4 years ago and except for the first couple days it was the easiest "diet" I've ever been on. I lost 40 lbs. slowly but consistently. I still do the fasting about 4 days/week, but really I pretty much eat whatever I want whenever I want now. I have always been a health conscious person so I don't eat junk food. Not sure about 16:8 for those folks that have to take morning meds with food...

Thanks for the article & links. I've been fooling around with this - just in the early stages now - so stay tuned. Weight loss would be a bonus but more interested in reduced BP, lower cholesterol levels and insulin responses.

I have been doing 16.8 for a couple of weeks in conjunction with WW green plan. I have lost 3.5 lbs in this time. I use my WW points within the 8 hour eating frame. I eat nothing after 6pm & have breakfast at 10 am. This is suiting me so far. however, when entertaining or going out it will not be possible to fast for 16 hours so on the odd occasion the fast will probably not start until around 10 pm so therefore will end up being 12.12! Don’t know if anyone else finds this?

Just my two cents: I find it curious that for decades no matter what the diet focused on (low fat, low carbs, whatever), they all agreed that skipping meals was bad. Now we have a diet that is just that: skipping meals. Also, those I know who do IF (usually in conjunction with Keto) are fanatical about it. They insist it's the one true way and talk about it non-stop, whether others want to hear about it or not. )And I say this as a CrossFitter. :) ) I know not everyone is that militant about it, but that has been my experience. For me, I know I would be hangry during the fasting period, so I stick with normal calorie deficit when I want to lose weight.

I lost 25 lbs on WW. Once I started having consistent wt loss, I started taking Fridays off. I think my wt loss continued because I never did it 2 days in a row, & I still journaled my food. Hope this helps!

I've been doing 14-hour fasting for about three months. I can't seem to make the hurdle to 16 hours. Having said that, the weight gain has ceased. Warmer weather is coming up, so I hope that increasing activity with more walks will help.

When I was doing IF, I never skipped a meal. I just fit my meals into the 8 hr. eating time. I was on wt watchers too, so I saved most of my points for the last I wouldn't b tempted to snack.

This was a well written article and described this lifestyle eating plan accurately!

I started the 16:8 intermittent food plan 4 years ago and fell in love with it. Had nothing to do with weight loss; it boiled down to how it made me feel. And I did drop 20 pounds very slowly which of course was a bonus.

I would like to make a comment about this idea of skipping a meal on this way of eating. You really are not skipping any meals. From 11:00 am to 7:00 pm you get all 3 meals in plus snacks. Our society has beaten us down that everyone in the world wakes up at 7:00 am has their breakfast and lunch and dinner follow accordingly. Well what about all the folks who work graveyard shifts. Are they suppose to set an alarm and get up at 7:00 am just to say they don't want to miss their breakfast? I see no difference in a first meal of the day kicking off at 11:00 am vs. 7:00 am.

I promise anyone out there that you will feel 100 times better because you gave the work horse organs a much needed break..!

I have been on 16:8 version for almost 2 years and have lost 20 lbs. It's not hard now and I do go off when traveling. It takes getting used to but so worth it when you step on the scale. Now I need to get back to workouts.

I would just like to add in reply to some comments that no meals are skipped. All 3 meals are eaten within the 8 hour window. Therefore the best of both worlds is achieved.


I have just fooled around with IF. I am on WW maintenance as a lifetime member. When I need to take off a pound or two before monthly weigh in, I often do 14/10. It seems to help and going 14 hours without eating isn’t so difficult but still helps. I eat my normal WW foods which are healthy.

I started IF in January. I have lost 14 lbs to date. I am mostly following a 20:4 schedule. I do extend the eating window on the weekends. It has been an amazing change for me psychologically. I have been a person who has focused on my next meal for my whole life. IF has freed me up from this thinking.

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