Could Intermittent Fasting be the Next Big Weight Loss Tool?

InpharmD™ Clinical Literature Summaries — S3E15

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On behalf of all of us here at InpharmD, whether you’re listening to this from your home or on the front lines, we hope you’re well and we thank you for the important work you’re doing.

With this podcast, we recap innovative, practice changing studies in ten minutes or less. And remember, nothing here is medical advice; we just present the evidence and our (sometimes hot) takes.

Could Intermittent Fasting be the Next Big Weight Loss Tool?

Obesity is a worldwide problem, and America hasn’t been spared. While on paper weight loss seems easy, in practice it can be very difficult to obtain consistent, long term results. There are a few factors involved. First, when lifestyle changes are made to try to lose weight, they can be very hard to maintain. Second, the body itself has a tough time losing weight. As one loses weight quickly, the body realizes this and actually can change metabolism and hunger signals in order to try to prevent further weight loss and even gain that weight back. This is probably an evolutionary response that goes back to when we were hunter gatherers. Back then, conserving our energy in the form of fat stores was vastly more important than it is now-a-days.

So given that obesity comes with all sorts of health risks, we’ve been continuously trying to find safe and effective solutions for long term weight loss. One of the more recent crazes has been something called intermittent fasting, where you’re only allowed to eat during certain hours of the day. There’s been plenty of debate on this approach, so we figured we should check out the evidence.

In the study we’ll look at today, the authors randomized 139 overweight adult patients to calorie restriction PLUS intermittent fasting or just calorie restriction alone. Basically both groups could only eat a certain number of calories per day, but in one group those calories could also ONLY be eaten between the hours of 8 AM to 4 PM. They maintained this approach for 12 months and then looked at the primary outcome of change in weight from baseline.

The mean weight loss in the intermittent fasting plus calorie restriction group was 8 kilograms, whereas in the calorie restriction alone group it was 6.3 kg. While there as a trend towards a difference, it was not statistically significant. None of their secondary outcomes such as changes in lean body mass, body fat, lipid levels or blood pressure were significantly different between groups either.

Adherence to the calorie restriction and intermittent fasting in both groups was good at about 84%, and a total of about 85% of patients completed the whole 12 months of the study. While studies on intermittent fasting have shown some different results, this trial paints a pretty clear picture that weight loss is primarily due to calorie restriction, and that intermittent fasting doesn’t add a whole bunch on top of this. Now certain people might be able to restrict calories more effectively on an intermittent fasting schedule, but at the end of the day the calorie restriction is clearly whats important.

We do need to keep in mind that this study was done in China, and thus results could be different if done in America given the different environments, diet and lifestyle. Additionally, patients with diabetes and cardiovascular disease were excluded from the trial, so we can’t apply results to them despite the fact that they often stand to gain the most from weight loss.

So at the end of the day, this study doesn’t show us anything groundbreaking with intermittent fasting. Really the same old calorie restriction seems to do the trick. With that being said, there are always new weight loss strategies being tried out, so you’ll hear from us if anything groundbreaking is discovered!

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The InpharmD Podcast is an independent production of InpharmD. Check out more evidence-based information at inpharmd.com

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