The question raised today is whether fasting alternately during the day is a viable option, perhaps even more suitable for those who want to experiment with intermittent fasting. I’ve written many times about fasting here on the blog because it’s one of my favorite tools for managing insulin, blood sugar, appetite, and (possibly) promoting longevity, but I never dedicated a single post about alternate day fasting. . Time to fix that.
I call it a tool, but fasting – having regular, clear periods, little or no eating – is the natural human condition. Or at least it should be. Like I mean, physiologically, some of the best things happen when we don’t eat. Fasting stimulates desired hormonal responses, reduces oxidative damage, promotes autonomic processes, and provides mental challenge. Of course, in today’s food-rich environment, most people eat as often as 16 to 18 hours a day. Eating between 6 and 8 hours, much less 24 hours or more without food, is rare.
For the most part, I don’t believe in optimal fasting schedules. Whether someone prefers time-restricted eating like the popular 16:8 or 18:6 protocol, weekly 24-hour fasts, semi-annual fasts lasting three days or longer, or WHEN (when) naturally occurring hunger) is a matter of personal preference. Each has its pros and cons, but neither is so compelling that I’d say which is clearly the best for everyone. Since many people seem inclined to try intermittent fasting during the day, it deserves a closer look here.
What exactly is Alternate Day Fasting?
There are two major types of alternate day fasting (ADF):
True ADF where you skip eating all day. Eat this day, don’t eat the next day. Simple, not necessarily easy. With this type of ADF, you will fast for 36 hours (dinner one day to breakfast two days later) every other day. Maybe even longer.
Modified ADF is where you eat every day, but alternate between days when you eat normally and days when you significantly restrict calories. The general rule of thumb is to consume 25% of your typical daily calories. If you normally eat 2,400 calories, your week would look like this:
Day 1: 2,400 calories
Day 2: 600 calories
Day 3: 2,400 calories
Day 4: 600 calories
Day 5: 2,400 calories
Day 6: 600 calories
Day 7: 2,400 calories
Also, whatever goes. You can combine ADF with just about any diet — Primal, keto, vegan, carnivore, even SAD (though I don’t recommend it for obvious reasons). There aren’t any rules about when or how often you eat on your normal eating days, but the idea is to consume the same amount of calories you eat to maintain your weight, perhaps a little more. Assuming you don’t eat wild, you’ll run into a sizable calorie deficit even if you eat normally half the time.
There are also some specific variations in the ADF:
- 5: 2 fasting perhaps the most famous. This is similar to the modified ADF, but instead of eating less every day, you choose two days per week, usually not in a row, to limit calories.
- Eat stop eating, the brainchild of Brad Pilon, is a modified type of ADF where you do one or two 24-hour fasts per week. Once or twice a week, you eat dinner one day and then don’t eat again until dinner the next day (or breakfast to breakfast, lunch to lunch, whatever you like).
- Daily Diet was devised by Krista Varady, PhD, now Professor of Science and Nutrition at the University of Illinois, Chicago, and the author of dozens of scientific articles on the topic of fasting, and the same popular book. Name. Here’s your typical modified ADF approach with one notable difference: you’re allowed to eat ad libitum (as much as you want) on meal days. According to Varady, most people still run into a calorie deficit and lose weight even during “holidays.” Some readers of her book, The Every Day Diet, begged to be different. However, she has had success with this method in her academic work.
Benefits of Alternate Day Fasting
Possible benefits of ADF include:
- Reduced fasting insulin (but inconsistent effects on insulin sensitivity)
- Lower triglycerides (plus LDL and total cholesterol if you do)
- Lower blood pressure
- Reduces adipokines associated with systemic inflammation and cardiovascular disease
- Promotes ketosis
If it sounds like I’m underwriting my bets here, it’s because there’s no standardization on how researchers use the term “alternating day fasting.” There’s a lot of promising data, but it’s hard to generalize from one study to the next as one study used the Eat Stop Eat design and the other used 5:2 with two consecutive days of fasting. customary. The metabolic effects may not be the same.
Researchers are still trying to figure out if any of these benefits are unique to fasting or are largely due to the calorie restriction inherent in these types of fasting procedures. That’s an open question at this point, though I suspect there’s more to fasting than mere calorie restriction.
What about weight loss? Can Alternate Day Fasting Help You Lose Weight?
Right. This has been demonstrated in many studies using different types of ADF and different populations. Not to mention all the anecdotal evidence.
The more interesting question is whether you are likely to lose than weight — or lose weight more easily — with ADF. The available studies seem to suggest that although you may lose more weight with ADF in the short term, Fasting and regular calorie-restricted diets (aka “continuous calorie restriction”) eventually run out even when the calories are right. For ADF compared to other fasting patterns such as daily time-restricted eating, there aren’t enough studies overall to draw conclusions one way or the other.
“But wait,” you say, “I couldn’t lose any weight when I tried to diet until I started fasting.” I hear this a lot. Just because ADF may not have an average weight loss advantage doesn’t mean it’s not in your favor. When it comes to weight loss, diet adherence plays a big role. Many people find it easier to stick to a schedule where they don’t have to restrict food every day.
The Downside of Alternate Day Fasting?
To do the ADF properly, you must keep track of your food, which can be difficult. Those who don’t want to measure every bite can try the Eat Stop Eat method, which doesn’t limit what you can eat on fasting days (or more precisely, at the end of a 24-hour fast). hours).
Eating just 500 or 600 calories isn’t easy, especially if you want to break it down into several meals or snacks. You’ll want to limit your fat intake as fat is the highest calorie macronutrient at 9 calories per gram. Once you get enough protein, there’s very little room for anything else. I recommend eating only one or two meals on fasting days and adding low-calorie, non-starchy vegetables like leafy greens. Sipping on bone broth can also help stave off hunger, but that’s it will being hungry, especially in the head.
One potential concern is the maintenance of lean mass. Across four studies with overweight/obese adults, on average dieters lost more lean mass with ADF than with continuous calorie restriction (regular dieting). These studies lasted from 12 to 30 weeks and the participants ate a reasonable amount of protein. However, none of the studies provided exercise guidelines, and it is unclear if any of the participants did resistance training.
The Bottom Line: Alternate Fasting Today Or Today?
Overall, the benefits of ADF appear to be consistent with the benefits of fasting in general. From what I can tell, the biggest advantage of ADF over a daily time-restricted diet or a calorie-restricted diet is that some people find it easier to apply.
The lean mass-related findings give me pause, but not enough to rule out ADF at this point. While the four studies were fairly consistent, there was also a lot of variation between participants. Whenever you eat in an energy deficit, you need to make sure to eat plenty of protein and lift heavy loads to protect your muscles. It’s just the best method no matter what type of fasting you’re doing. That said, the rigorous ADF I outlined above leaves you in a 33 percent power deficit, which is quite large – perhaps too large to be safely maintained long-term. We could use more human studies here to shed some light on all of this.
And speaking of best practices, it’s what you eat on your non-fasting days that matters. While the ADF doesn’t have strict requirements, it makes sense to eat the same nutrient-dense foods whether you’re doing ADF or not.
Finally, the same rules apply to people who shouldn’t fast: people who are already stressed out and people with high energy needs such as competitive athletes, children and adolescents, and those who are pregnant or breast-feeding.
Okay, what do you think? Yes or no, are you interested in alternate day fasting? If you tried it, how did it go?
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