Weight loss trends come and go as quickly as the DoorDash delivery guy, but there is one exceptional diet that doesnt seem to be going anywhere, and thats intermittent fasting. Its benefits go far beyond the simple weight loss other diets promise, and current research has just scratched the surface, leaving much more to learn. Intermittent fasting has been linked to better immunity and lower disease rates because foregoing food for a short period has been shown to help the body's immune system fight off infections. Studies also show it may help stop the clock on aging, fend off obesity, and lead to longer lifespans.
The most popular type of intermittent fasting is time-restricted eating, or only eating within an 8-to-10 hour window each day. Another well-publicized alternative method is known as alternate-day fasting, which involves fasting for longer windows of time, such as 24 hours or even 36 hours, followed by periods of unrestricted eating.
It appears to work for weight loss and disease prevention, according to some scientific studies. But is alternate-day fasting practical and effective for the long term compared to typical calorie-restricted diets?
We consulted the research and nutrition experts for a holistic answer. Here, youll find an explanation of what clinical trials have shown, plus practical advice from Skylar Griggs, MS, RD, LDN, a registered dietitian and owner of Newbury Street Nutrition as well as lead dietitian for the preventive cardiology division at Childrens Hospital Boston; and Jill Edwards, MS, CEP, Director of Education for the T. Colin Campbell Center for Nutrition Studies.
The alternate-day method of intermittent fasting allows for unrestricted eating one day, or feasting, followed by a full day of fasting. On fasting days, advocates for this style of intermittent fasting suggest consuming only 25 percent ofyour normal caloric intake, rather than foregoing food altogether. So if your normal food intake amounts to 2,000 calories a day, you would eat 500 calories on fasting days, according to this plan.
Comparing alternate-day fasting with calorie-restricting diets, studies havesuggestedthat they work equally wellfor weight losssince at the end of the week you've had approximately the samenumberof calories on each.People on analternate-day fasting dieteat about one-third fewer calories overall for the week,which is comparable to a calorie-restricted diet.
On an alternate-dayfastingdiet,you would eat about 9,500 calories over the course of a week,or about 1,000 less than if youate 1,500 calories per day on a calorie-restricteddiet. This is significantly less than the standard 2,000 calorie-a-dayintake which amountsto 14,000 caloriesover the course of a week and would result in losing between 1 and 2 pounds a week (since a pound is equal to 3,500 calories).
Proponents of this diet method tout the freedom it allows on feasting days: Diet only half the time! proclaims the subtitle on one popular book on the subject. Delay, dont deny, declares another.Covers of these books feature images of processed and animal foods, like donuts and burgers.
There are no widely accepted guidelines on what to eat on feasting days, and this is certainly a big part of the appeal for many who try it: The reward for fasting is feasting! Still, if weight loss is a goal, it stands to reason that choosing plant-based whole foods like nutritious fruits and vegetables, whole grains and legumes, nuts, and seeds would be much more beneficial than processed junk, and lead to better health as well.
Many people will begin their feasting day by eating soon after waking up,then continuing to eat as they wish through bedtime.Others might fast from after dinner one day say, from 7 p.m. on Sunday and then break their fast for a 7 p.m. with dinner the following day, in this example, Monday evening. They wouldthen have afeasting day on Tuesday, through 7 p.m., and then fast on Wednesday.
People can plan their alternate-day fasting schedule in advance and decide which days of the week they choose as fasting or feasting days. A fasting day might include nothing more than a light lunch and an early modest dinner, so its better to plan to feast on days that include social engagements.
If this sounds like something you would like to try, there is science behind why and how it works. (If not, you're not the only one who finds the schedule unappealing, studies show.)
Research has shownthat animals placed ona variety of fasting regimens, including alternate-day fasting, experienceextraordinary health benefits, including longer life spans, and slowed or reversed signs of aging. They also benefit from a reduced incidence of disease and other negative health outcomes, including diabetes, cancer, high cholesterol, cardiovascular disease, neurodegenerative diseases, and obesity.
While human research is still emerging, a 2017 randomized controlled trial study on obese adults was less optimistic than the animal studies, showing the subjects who tried alternate-day fasting had the same amount ofweight loss as thegroup assigned to a traditional calorie-restricted diet. One note: The people in the alternate-day fasting group did not adhere to the prescribed calorie count, eating more than the recommendedamount on fasting days, and alsoless than they were supposed to eat on feasting days. The dropout rate was also higher in the alternate-day fasting group (38 percent)thanthe calorie-restricted group (29 percent), indicating it's harder to sustain this type of dieting.
A more recent randomized controlled trial study on alternate-day fasting in healthy humansshowed more positive results. The 2019 report showed a number of beneficial outcomes for the alternate-day fasting group compared to the control group.
The benefits of alternate-day fasting included:Body fat loss (particularly around the belly); improved cardiovascular health; reduced levels of an age-associated inflammatory marker; and lower levels of LDL (or so-called "bad") cholesterol.
So, with promising initial findings, why isnt everyone fasting? One perspective is quite simply that its hard to go without food for large chunks of time. Unlike a lab animal, most humans arentfedrestricted rations on a controlled schedule. We also dont live in a carefully monitored biodome, and people on a Western diet are used to eatingthree meals a day plus snacks. There's little support or precedence for eating differently.
But for people trying to lose weight, more traditional calorie-restricted diets pose their own challenges. Our bodies havent caught up to the evolution of our food systems were still hard-wired to prefer calorie-dense foods such as sweetsand high-fat foods, which would have been a rare and valuable find for our foraging ancestors but are now readily available at every drive-through, food court, vending machine and grocery store.
This biologically-ingrained urge to indulge is what drives many dieters to try alternate-day fasting, since it allowsthem to eat with abandon several days a week. This kind of freedom surely comes as a relief for anyone who is tired of constantly counting carbs or calories.
Plus, thepotential benefits ofslowing the aging process, improving cardiovascular health, and slashing LDL cholesterol while helping the immune system fight off potential infections likely attract a few takers too.
Skylar Griggs, MS, RD, has counseled thousands of clients on their nutrition and weight loss goals over the course of her career, but she has not recommended alternate-day or any style of fasting to any of them, for a few reasons.
First, the majority of the studies conducted on alternate-day fasting so far have been on animals. And for those studies done on humans, weight loss has not appeared to be significantly different than for people following standard calorie-restricted diets.Weight loss and weight management are the primary reasons people come to me, she said, And the research on weight loss is fairly limited. Second, people show poor long-term adherence to extreme diets, Griggs has found, and she putsalternate-day fasting in this category.
Any diet that is extreme and not approachable is hard to follow, said Griggs. Any diet you cant do 80/20 [80 percent healthy, 20 percentwiggle room] is not sustainable. When the plan is a bit malleable when it can bend a little bit people are more likely to stay with it.
Alternating between feast and famine days could also have negative effects on the metabolism, Griggs says,ultimatelyinhibiting weight loss and causing other health issues.
I think any time you restrict yourself down to 500 calories, youre just creating a disaster," she warns. "The body is so hungry, its likely to cause a decrease in metabolism and your body to go into starvation mode, Griggs said. Youll be more likely to overdo it the next day, and then with binge-type days, over time, triglycerides and blood pressure can become elevated.
The black-and-white thinking that alternate-day fasting encourages can be worrisome for people prone to eating disorders, says Griggs, who served as the lead outpatient dietician for Renfrew Center of New Jersey, an outpatient center for women with eating disorders,It follows a pretty typical eating disorder pattern: Restrict. Binge. Restrict again."
Overall, Griggs advised that people seeking to lose weight should stick to a more traditional plan and avoid going more than 4-5 hours without food during the day to keep the metabolism chugging along and avoid late-night eatingsince that'swhen people are most likely to overeat.
I think a lot of people are looking for the shiny new thing they think is going to be the answer," Griggs said. "But the things that are good for your healthare not usually super sexy. Instead, she advises: Eat fruits. Eat vegetables. Increase your fiber intake. Include healthy fats. Eat consistently during the day. These are not going to be on the cover of a magazine, but theyre definitely good for your health.
For those still bent on giving alternate-day fasting a try, Griggs has this advice: Whatever [diet] you decide to do, getting a dietician looped in is super important. Get the support of someone who is based in science and has gone through a lot of school, training, accredited programs, and hospital internships. Dont just go to, say, your gym for advice.
Alternate-day fasting style is not the number-one choice of another respected expert,Jill Edwards, MS, CEP of the T. Colin Campbell Center for Nutrition. For Edwards, the main objection is primarily for practical reasons.
Research has shown that it is not at all sustainable. Life happens. You have a luncheon, your kids have a birthday party. If youre only eating 500 calories a day, it makes it hard to sit down for dinner with your family, Edwards said. She has a personal friend who'd tried the diet style.
Id ask her to get lunch, and shed say, I cant, this is not my eating day, Edwards said. I think she lasted two weeks. The same friend then switched over to the time-restricted version of intermittent fasting, which requires eating every day within an 8- or 10-, or even 12-hour window. She had great success with this approach, which is the same type of intermittent fasting that Edwards herself practices and advocates.
More people would be medically eligible to practice this eating pattern as opposed to alternate-day fasting, Edwards notes, because of the comparatively shorter periods of fasting. With time-restricted eating, you get all the benefits of intermittent fasting, but its much more manageable. Youre eating according to your bodys internal clock,your circadian rhythms, and keeping the same cycle every day, she said.
Your body utilizes more fat stores in the morning as its way of planning to get through the day without the need to eat through the night. And then on the other end of that, you automatically cut out late-night eating, which is what sabotages your circadian rhythms, and according to research, leads to weight gain.
In other words, because people practicing the time-restricted version of intermittent fasting will eat, say, only between 11 a.m. and 7 p.m., they strategically use the bodys tendency to burn fat stores in the morning, and also shut down snacking at night, which is the time people generally go off the rails with their calorie intake and make poor food choices.
There is a magic number. We should not consume any calories not one piece of fruit or a cracker after 7 p.m. That way you have less gastrointestinal distress, higher sleep quality, and better weight management, Edwards said (though she personally makes exceptions on the weekends).
For people who want to make a go of the alternate-day fasting diet anyway, Edwards advised that they choose their feast day foods with care. You want to make the most of the calories and choose nutrient-dense foods on the days youre eating a lot. Dont stuff your face with calorically dense food that isnt nutrient-dense, she said.
As far as whether the health benefits of fasting would be compromised if one binged on junk food during their feast day, Edwards said the jury was out. Its hard to say because fasting is very powerful. But to me, its like smoking a cigarette and having an orange afterward. The orange is going to help scavenge some of the free radicals, but not all of them. So my thing is, dont smoke the cigarette, she said.
For the fasting-curious, Edwards pointed to the TrueNorth Health Center, a facility that specializes in medically supervised water fasting, as a resource for many well-documented case studies of the powerful effects of fasting on health. And, like Griggs, Edwards advised anyone considering trying alternate-day fasting to consult a medical professional first.
While experts dont all agree on whether any type of intermittent fasting is to be advised, recent studies and the two above-featured nutrition experts all align on at least five points when it comes to alternate-day fasting.
Check with your dietician or medical expert before you embark on any new diet. If you decide to try alternate-day fasting (and youre medically cleared to do so), choosing foods that are mostly plant-based and healthy on feast days, rather than processed foods high in unhealthy saturated fat and added sugar, is likely to enhance your results.
See the rest here:
Should You Try Alternate-Day Fasting? Here's What the Experts Say - The Beet
