Intermittent Fasting for the Over-50 Adult
Should you give this popular diet trend a try?
In case you haven't noticed, intermittent fasting is hot right now. Fueled by recent research, it's being touted by many popular health and fitness magazines, websites and blogs.
But is intermittent fasting a good strategy for 50+ adults? We explore that question here.
What Is Intermittent Fasting?
The term intermittent fasting (IF) can apply to any number of very different dietary protocols. Unlike "true" fasting, where no calories are consumed for a sustained period of time, intermittent fasting often allows some calories even on "fast" days, and those days are interspersed with normal-calorie "feed" days.
Alternate-day fasting (ADF) involves consuming from 0 to 25 percent of daily calorie needs on alternate days, with normal feeding in between. The 5:2 IF diet is similar, except that 25 percent of calories are consumed on just two non-consecutive "fast" days per week, with normal feeding on the other five days.
Finally, there is time-restricted feeding (TRF), which really isn't fasting at all, but where normal feeding is restricted to a relatively short period of time (between 10 a.m. and 6 p.m., for example), on an ongoing basis.
What’s All the Fuss About?
A quick scan of the latest literature on IF suggests that this relatively simple dietary strategy can prevent or cure nearly anything. According to a sampling of book titles on Amazon, intermittent fasting can help you: lose weight, build muscle, boost your metabolism, lose fat, improve your memory, heal your body and be more productive.
While many of these claims will sound familiar to anyone who's ever tried a fad diet, the research behind those bold book titles actually holds quite a bit of promise.
Still, experts caution that there are potential risks. Fasting can be dangerous for those with diabetes or other conditions where maintaining stable blood glucose levels is important. Abstaining from food while exercising can result in low blood sugar, which can cause dizziness, lightheadedness and confusion. And for people who take medications for heart disease and high blood pressure, fasting may cause risky electrolyte imbalances.
What the Science Really Says
Scientists have been studying fasting and meal timing protocols for many decades, but in recent years, as more sophisticated methods have come into play, the field has really exploded. The current buzz is the result of many studies that have shown favorable results not only for weight loss, but also for improving metabolic factors like insulin resistance and lipid profiles, as well as protecting against cognitive decline, fighting cancer and even slowing down the aging process.
The trouble is, most of these studies have been performed on laboratory animals (like mice and worms), and nearly all of the human trials have been relatively short-term with small sample sizes.
The results of a somewhat larger, year-long human trial were considered disappointing to the field — IF did help people lose weight and improve lipid profiles, but it did no better than a typical calorie-restricted weight loss protocol. In addition, the subjects in the IF group had the highest dropout rate (13 out of 34 left the study) and cited the difficulty of sticking to the protocol as the most common reason for quitting. This was in sharp contrast to earlier studies that showed very high rates of adherence to IF protocols when the trial times were shorter (eight and 12 weeks, for example).
While more research is needed to determine whether and how IF and TRF can be most beneficial, researchers and other experts agree that it's already an important tool in the fight against obesity. As one review of the literature succinctly put it, "Ultimately, it is the degree of dietary adherence and sustainability, rather than the type of dietary strategy, which will predict weight-loss outcomes."
In other words, people are different, and some people find intermittent fasting or time-restricted feeding easier to stick with than cutting calories each day. In fact, a few studies have shown that people following a TRF protocol lost weight even though they had been instructed to eat "ad libitum," or at will.
Sharon Lehrman, a registered dietitian nutritionist and owner of Nutrition, Health and Wellness in St. Louis Park, Minn., has recommended fasting for her clients, around 70 percent of whom are over 50.
She uses something very similar to the 5:2 IF protocol, "mainly with people who have already lost weight, and we're using it more for maintenance." Why not for weight loss? That could be effective, she said. However, it's very slow. "It's probably going to be a pound a week," says Lehrman.
Lehrman also agreed with researchers that what works for one person may not work for another. "There really is no one perfect diet. People can lose weight and maintain weight on a really wide variety of food patterns. So it really makes sense to work with people where they're at," she says.
Kathleen Clinesmith, 76, tried time-restricted feeding as a way to improve her diet and hopefully reap some of the reported long-term benefits of IF.
Clinesmith, of New York City, said she finds it easy to confine all of her eating to just eight hours a day, from around noon to 8 p.m.
"It really reshapes how you think about food," she said. "If you're hungry, you don't always have to run and get something to eat." After practicing TRF "not religiously, but pretty consistently" for nearly seven months, Clinesmith noted, she lost around seven or eight pounds. (Weight loss had not been her primary motivation for trying the diet.)
The Bottom Line
Research and anecdotal evidence suggest that for those who find a protocol they can stick with, intermittent fasting or time-restricted feeding could be a novel and effective weight loss tool.
Regardless of your health status, it's a good idea to consult with your doctor or a licensed nutrition professional before trying any new diet.