source: Stuff NZ author: Niki Bezzant TUESDAY, Jan. 26, 2022
Many people are embracing intermittent fasting, particularly in an effort to lose weight, but should they be? Niki Bezzant talks to those in the know.
Intermittent fasting is firmly on the list of popular diets people might turn to when looking to lose weight and get healthier. But is it actually good for us?
There is yet to be a clear scientific answer. There’s a growing body of evidence on intermittent fasting and its cousins, calorific restriction (eating drastically reduced amounts) and time-restricted eating (eating only within a restricted time frame, usually eight to 10 hours a day).
A lot of the research has been done in animals rather than people. But the human studies show some interesting things.
For weight loss, fasting can be effective, as you might expect. Fasters are limiting their calories and, depending on the type of diet being followed, this will work in much the same way as other diets.
There is also evidence that various forms of fasting could improve glucose regulation and blood pressure, be good for cardiovascular health, and encourage abdominal fat loss.
And there are studies linking fasting with potential benefits for some neurological disorders and cancers.
A review on the effects of intermittent fasting on health, ageing, and disease, published in the New England Journal of Medicine in 2019, raised these tantalising possibilities, but also pointed out that more research is needed to see what the long-term effects and safety of fasting diets are, and how they might work in different age groups, since studies have focused mainly on young and middle-aged people.
Its authors wrote: “It remains to be determined whether people can maintain intermittent fasting for years, and potentially accrue the benefits seen in animal models.”
.
Fasting for weight loss
Professor Sir Jim Mann, director of the Edgar Diabetes & Obesity Research Centre at Otago University, says weight loss is generally beneficial for people with type-2 diabetes, and fasting can be a useful way to lose weight, if done properly.
“It seems to work for quite a lot of people, and I think provided it’s done sensibly – and there are quite a lot of published approaches to it, which are fairly sensible – I don’t think it’s harmful,” he says.
“And, of course, it’s a practice that has been done for centuries for aesthetic and religious reasons.”
Registered nutritionist Nikki Hart says she is often asked about fasting. She agrees with Mann, but says there are pitfalls, and other approaches to look at too.
“I always come back to the fact that if you’re only doing it for weight loss, it might not work,” she says. “We’re seeing some people play catch-up with their calories later, so they’re eating the same amount of food. If that happens, you’re not going to lose weight.”
She says other more long-term approaches might work as well or better.
“A diet that’s lower in refined grains and sugar, or a plant-based, Mediterranean-style diet, seem to do the same thing.”
Fasting for diabetes
For people with insulin-dependent diabetes, Mann and Hart say fasting is a no-go zone.
Mann clarifies that for someone with type-2 diabetes, which is being managed by diet alone, fasting would be unlikely to be harmful. But, he says, “I would be very reluctant to recommend it to people with diabetes [who are] on any form of medication, because of the risks of hypoglycemia.”
Hart says “absolutely not” to fasting for those with existing diabetes. But, for someone who has got pre-diabetes, or who has been told they are insulin-resistant, “then I think it may be useful … it might not offer them weight loss, but they might be in better control of their insulin levels”.
She points to a small study in which obese men with pre-diabetes tried a form of intermittent fasting called “early time-restricted feeding,” where all meals were within an early eight-hour period of the day (7am-3pm).
Compared to another group who ate within a 12-hour window, the time-restricted eaters had lower insulin levels and improved insulin sensitivity, as well as significantly lower blood pressure. However, it should be noted that neither group lost weight.
Fasting pitfalls
There are some other potential issues with fasting diets to keep in mind. Hart says she worries that restrictive eating can tip some people into disordered eating behaviour.
“Especially in our young people or those who may have poor body confidence issues, they might be treating [fasting] as a way to diet. If that restricts them, and then they start restricting further and further, will that then push them into a space of anorexia?
“Or if they’ve had anorexia and bulimia before, will intermittent fasting trigger that again? That’s something to be really thoughtful about. I think we need to ask: what are your pre-existing issues?”
Another concern is one Hart sees a lot, and it is something that applies to all diets. To be effective, any diet (or “lifestyle” as they are increasingly described), needs to be done forever.
“When people come in and they go, I really want to try fasting, I say, well, are you sure you need to do that, and is it something you can do for the rest of your life? Is it something you’re prepared to live with?
“Most people find it difficult to fast, really. And so, are you only going to do it in the short-term? And, if so, what are you going to do then? How are your behaviours going to change when you stop doing the fasting? Will it be just another diet… a yo-yo thing that is going to make your insulin resistance worse?”
There are social aspects that Hart says need to be considered, too.
“In today’s world, where we are time-strapped and we are working longer, how feasible is it for you to be able to eat within that [short time] window, and then not eat later?” she asks.
“And is it anti-social when you are coming home to your family? What message does that send to children, that Mum and Dad aren’t having dinner with us at night time?”
Fasting pitfalls
There are some other potential issues with fasting diets to keep in mind. Hart says she worries that restrictive eating can tip some people into disordered eating behaviour.
“Especially in our young people or those who may have poor body confidence issues, they might be treating [fasting] as a way to diet. If that restricts them, and then they start restricting further and further, will that then push them into a space of anorexia?
“Or if they’ve had anorexia and bulimia before, will intermittent fasting trigger that again? That’s something to be really thoughtful about. I think we need to ask: what are your pre-existing issues?”
Another concern is one Hart sees a lot, and it is something that applies to all diets. To be effective, any diet (or “lifestyle” as they are increasingly described), needs to be done forever.
“When people come in and they go, I really want to try fasting, I say, well, are you sure you need to do that, and is it something you can do for the rest of your life? Is it something you’re prepared to live with?
“Most people find it difficult to fast, really. And so, are you only going to do it in the short-term? And, if so, what are you going to do then? How are your behaviours going to change when you stop doing the fasting? Will it be just another diet… a yo-yo thing that is going to make your insulin resistance worse?”
There are social aspects that Hart says need to be considered, too.
“In today’s world, where we are time-strapped and we are working longer, how feasible is it for you to be able to eat within that [short time] window, and then not eat later?” she asks.
“And is it anti-social when you are coming home to your family? What message does that send to children, that Mum and Dad aren’t having dinner with us at night time?”
If not fasting, what?
Hart reckons those of us who have got into bad eating habits during the pandemic – termed the “Covid confinement” effect – could probably get just as much health benefit by just cleaning up their acts.
“If we could eliminate late-night snacking, and really be observant of what a snack is during the day, then we might not need to do a fast,” she says.
Mann says fasting is just one option for weight and health.
“The long-term evidence is that no [diet] approach is better than any other approach. If fasting works for some people, good luck to them.”
Fasting gallery
