Is Intermittent Fasting (4:3) Better than Calorie Restriction?

The TLDR:

• This study compared two diet plans over a 12-month period to see which one was more effective for weight loss: 4:3 intermittent fasting (eating normally for four days and significantly reducing calories for three non-consecutive days) and daily calorie restriction (reducing calorie intake by the same amount every day).
• The participants were adults with overweight or obesity. Both groups also received behavioral weight loss support.
• The results showed that the 4:3 intermittent fasting plan led to a slightly greater amount of weight loss compared to the daily calorie restriction plan, but other studies show some conflicting results.
  
  

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Transcript:

Hello everyone, Dr. Wells here from Nutritional Physical Therapy. I'm here with my research helper today. This is Daisy.

We're here to talk about a new research update. This one's on a intermittent fasting diet. So some of you might know, I actually have a couple peer-reviewed publications on intermittent fasting, specifically within insect models.

These studies that we're going to talk about today, most of them are human trials, which are great. If you'd like to see more of those human trials, so we can actually see how these types of diets actually affect humans. That's ultimately what we're after, right? So this one's actually titled The Effect of the Four to Three Intermittent Fasting on Weight Loss in 12 Months.

It's a randomized control trial published by, I'm going to butcher the name, Kadanachi et al. This one's in the Annals of Internal Medicine, 2025. So what's interesting about this study is that they used adults 18 to 60 with a BMI that's considered obese to overweight.

The study was actually in Denver, Colorado, believe it or not. The intermittent fasting group that they used, what I liked is that it was kind of that four to three strategy. So three non-consecutive days per week, they were eating a restricted diet.

So they restricted them to 80% of total calorie intake. Whereas the other days there was ad libitum diet. So they could eat as much as they want.

The other group that they compared it to was normal dietary calorie restriction. So typically with that, they were trying to do about a 34% deficit roughly. So at the end, what do they find? Well, actually the group in the four to three intermittent fasting lost more weight.

So not only did they lose more lean muscle mass, but they also lost more fat mass, which is great. They also found that there was higher rates of being able to stick to the diet within the intermittent fasting group versus the calorie restriction group. So that's important because one thing that we struggle with in our interventions is getting people to stick to the diet.

And while in this particular study, we find that the people that are doing an intermittent fasting diet seem to stick with the diet better. Now that's a little different than some of the other studies that we've seen, like the five to two, which is like two extreme days of calorie restriction, five days of ad libitum eating. And some other studies, even with calorie restriction, they find it difficult to stick to a calorie restricted diet.

So at the end of the day, I think this is a nice randomized control trial. I think it offers us some insights. And I think at the end of the day, it comes down to what the patient wants to stick to in terms of reducing their calories.

If they're a person that wants the daily reduction and they seem to do fine with that, then that's great. If it's something that's difficult for them, then doing a time restricted feeding window, or like in this case, a day to day intermittent fasting type window is better for them, then that's great. So anyhow, hope you like this study.

Hope you like Daisy. And if you want more of this research stuff, check out our website, nutritionalphysicaltherapy.com. We got a lot of good content for a physical therapist and rehab professional. Thanks.