The 5:2 Diet and the Fasting-Mimicking Diet Put to the Test

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The effects of eating only 5 days a week or a fasting-mimicking diet 5 days a month.

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Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

What about instead of eating every other day, you ate five days a week, and fasted for the other two? The available data is actually similar to that of alternate-day fasting. About a dozen pounds of weight loss was reported in overweight men and women over a 6-month period with no difference found between those on the 5:2 intermittent fasting regimen and those on a continuous 500-calories-a-day restriction. The largest trial to date found an 18-pound weight loss within six months in the 5:2 group, not significantly different from the 20 pounds lost in the continuous calorie-restriction group. Weight maintenance over a subsequent six months was also found to be no different.

Though feelings of hunger may be more pronounced on the 5:2 pattern than an equivalent level of daily calorie cutting, it does not seem to lead to overeating on the non-fasting days. One might expect going two days without food might negatively impact mood, but no such adverse impact was noted for those fully fasting on zero calories, or sticking to just two packets of oatmeal on each of the “fasting” days  (which provided about 500 calories a day). Like alternate-day fasting, the 5:2 fasting pattern appeared to have inconsistent effects on cognition and lean mass preservation, and failed to live up to the popular notion that intermittent fasting would prove to be easier to adhere to than daily calorie restriction.

In fact, fewer subjects on the 5:2 pattern expressed interest in continuing the diet after the study was over compared to the continuous restriction control group, attributed to quality of life issues, citing “headaches, lack of energy and the difficulty of fitting the fasting days into their weekly routine.” However, there has yet to be a single 5:2 diet study showing elevated LDL cholesterol compared to continuous calorie restriction at six months or a year, offering a potential advantage over alternate-day regimens.

Instead of 5:2, what about 25:5, spending five days a month on a “fasting-mimicking diet”? Longevity researcher Valter Longo designed a five-day meal plan to try to simulate the metabolic effects of fasting by being low in protein, sugars, and calories with zero animal protein or animal fat. By making it plant-based, he was hoping to lower the level of the cancer-promoting growth hormone IGF-1—which he indeed accomplished, along with a drop in markers of inflammation, after three cycles of his five-days-a-month program.

One hundred men and women were randomized to consume his fasting-mimicking diet for five consecutive days per month, or to maintain their regular diet the whole time. After three months, the FMD group (the fasting-mimicking diet group) was down about six pounds compared to control, with significant drops in body fat and waist circumference, accompanied by a drop in blood pressures. Those who were the worse off accrued the most dramatic benefits. What’s even crazier is that three further months after completion, some of the benefit appeared to persist, suggesting the effects may last for several months. It’s unclear, though, if those randomized to the fasting-mimicking diet group used it as an opportunity to make positive lifestyle changes that helped maintain some of the weight loss.

Dr. Longo created a company to commercially market his meal plan, but to his credit says he donates 100 percent of the profits he receives from it to charity. The whole diet appears to mostly just be a few dehydrated soup mixes, herbal teas like hibiscus and chamomile, kale chips, nut-based energy bars, an algae-based DHA supplement, and a multivitamin dusted with vegetable powder. So, I figure, why spend 50 dollars a day on a few processed snacks when you could instead eat a few hundred calories a day of real vegetables?

Please consider volunteering to help out on the site.

Image credit: Couleur via pixnio. Image has been modified.

Motion graphics by Avocado Video

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

What about instead of eating every other day, you ate five days a week, and fasted for the other two? The available data is actually similar to that of alternate-day fasting. About a dozen pounds of weight loss was reported in overweight men and women over a 6-month period with no difference found between those on the 5:2 intermittent fasting regimen and those on a continuous 500-calories-a-day restriction. The largest trial to date found an 18-pound weight loss within six months in the 5:2 group, not significantly different from the 20 pounds lost in the continuous calorie-restriction group. Weight maintenance over a subsequent six months was also found to be no different.

Though feelings of hunger may be more pronounced on the 5:2 pattern than an equivalent level of daily calorie cutting, it does not seem to lead to overeating on the non-fasting days. One might expect going two days without food might negatively impact mood, but no such adverse impact was noted for those fully fasting on zero calories, or sticking to just two packets of oatmeal on each of the “fasting” days  (which provided about 500 calories a day). Like alternate-day fasting, the 5:2 fasting pattern appeared to have inconsistent effects on cognition and lean mass preservation, and failed to live up to the popular notion that intermittent fasting would prove to be easier to adhere to than daily calorie restriction.

In fact, fewer subjects on the 5:2 pattern expressed interest in continuing the diet after the study was over compared to the continuous restriction control group, attributed to quality of life issues, citing “headaches, lack of energy and the difficulty of fitting the fasting days into their weekly routine.” However, there has yet to be a single 5:2 diet study showing elevated LDL cholesterol compared to continuous calorie restriction at six months or a year, offering a potential advantage over alternate-day regimens.

Instead of 5:2, what about 25:5, spending five days a month on a “fasting-mimicking diet”? Longevity researcher Valter Longo designed a five-day meal plan to try to simulate the metabolic effects of fasting by being low in protein, sugars, and calories with zero animal protein or animal fat. By making it plant-based, he was hoping to lower the level of the cancer-promoting growth hormone IGF-1—which he indeed accomplished, along with a drop in markers of inflammation, after three cycles of his five-days-a-month program.

One hundred men and women were randomized to consume his fasting-mimicking diet for five consecutive days per month, or to maintain their regular diet the whole time. After three months, the FMD group (the fasting-mimicking diet group) was down about six pounds compared to control, with significant drops in body fat and waist circumference, accompanied by a drop in blood pressures. Those who were the worse off accrued the most dramatic benefits. What’s even crazier is that three further months after completion, some of the benefit appeared to persist, suggesting the effects may last for several months. It’s unclear, though, if those randomized to the fasting-mimicking diet group used it as an opportunity to make positive lifestyle changes that helped maintain some of the weight loss.

Dr. Longo created a company to commercially market his meal plan, but to his credit says he donates 100 percent of the profits he receives from it to charity. The whole diet appears to mostly just be a few dehydrated soup mixes, herbal teas like hibiscus and chamomile, kale chips, nut-based energy bars, an algae-based DHA supplement, and a multivitamin dusted with vegetable powder. So, I figure, why spend 50 dollars a day on a few processed snacks when you could instead eat a few hundred calories a day of real vegetables?

Please consider volunteering to help out on the site.

Image credit: Couleur via pixnio. Image has been modified.

Motion graphics by Avocado Video

Doctor's Note

How interesting was that?! All-you-can-eat above-ground vegetables for five days would have that same low amount of protein, sugars, and calories, with zero animal protein or animal fat. But, we’ll probably never know if it works as well, better, or worse since it’s hard to imagine such a study ever getting done without the financial incentive.

More on IGF-1 in my video Animal Protein Compared to Cigarette Smoking.

So far in this fasting series I’ve covered the basics of calories and weight loss:

…water-only fasting:

…and types of alternate-day fasting:

I close it out with time-restricted eating in Time-Restricted Eating Put to the Test and The Benefits of Early Time-Restricted Eating, coming up soon.

If you want them all in one place, I’ve also done three webinars on fasting: Intermittent Fasting, Fasting for Disease Reversal, and Fasting and Cancer, which are available here for download individually or as a set.

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