How effective is the keto diet or intermittent fasting for weight loss?
Celebrities swear by them. The rest of us would probably have at some point, tried one or other of its many variations, likely in January (billed as “National Dieting Month” in the United States) as we attempt to embark on New Year resolutions after all the festive feasting. The key word: attempt. But are the latest dietary trends sustainable in the long run? Do they actually work? Hear what a former food writer, a personal trainer, and a dietitian have to say.
To be sure, dieting isn’t a modern phenomenon. In the 1960s the cabbage soup diet was popular for weight loss if one could cope with dizziness and fatigue, and Weight Watchers also began around that time. The early 1970s saw the grapefruit diet, followed by the Sleeping Beauty plan, which even the “King of Rock” Elvis Presley was supposedly a fan of. If you’re sleeping then you’re not eating – but not without health complications.
Meanwhile, the paleo diet can be traced back to the 1980s, while the Atkins diet – which started in the 1990s – regained popularity when Kim Kardashian credited it for helping her shed extra pounds after childbirth. Then in 2011, it was as if Americans woke up and collectively agreed to start throwing coconut oil into everything, as Harper’s Bazaar puts it. This was soon followed by juice cleanses and diet pills. In recent times, the flavours of the day have been the ketogenic (keto) diet and intermittent fasting (IF).
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The keto diet is essentially a high-fat, low-carb meal plan where people aim to consume only about 5 to 10 per cent of their total calories as carbs. It comprises of mostly fats, and moderate protein. The idea is that a drastic reduction in carbs will put the body into a metabolic state called ketosis – where the body begins to burn fat, instead of sugar, for fuel. The liver also produces ketones from fat, which can supply energy throughout the body, especially for the brain.
Separately, IF is an eating pattern that cycles between periods of fasting, with either no food or significant calorie reduction, and periods of unrestricted eating. Popular versions of IF include the 5:2 diet, which allows for normal eating for five days, and a low-calorie diet of about 500 calories per day on two non-consecutive days of the week. Another version of IF is the 16/8 diet, where one fasts for 16 hours each day, and eats only within an eight-hour nutritional window.
former food writer
When Ms Cheah first heard that her triathlete friend had shed two to three kilos within two weeks of trying out the keto diet, she was intrigued. “She was losing the weight which all her healthy food eating, or running, swimming and biking, didn’t even help,” Ms Cheah says.
Encouraged by her friend’s results, she decided to give the keto diet a go and lost four kilos within two months. By the third day of her diet, she also experienced fewer aches and less soreness on her shoulders. That said, while she did enjoy various health benefits including being more energised, Ms Cheah also noted that she felt constipated at times, and had skipped her period the first time she went on a strict keto diet. The diet can be “pretty drastic” on the body, and different people might have completely different reactions to it, she adds. Other side-effects she has heard of include hair loss and the tendency to urinate more often.
Nonetheless, since switching to a moderate keto diet – which allows for slightly more carbs – the side-effects Ms Cheah experienced have eased up. With the keto diet, she notes, she lost weight initially, before hitting a plateau after about three months, and then regaining some weight, no thanks to the durian season and family festivities.
Asked whether she missed carbs during the dieting, Ms Cheah replies that her greatest revelation was that she didn’t crave carbs once she had eaten sufficient fats. “Sometimes your palate might crave a bit, but once you pass the two-week mark, it’s easier. If I can, anybody can,” she says.
She reveals that her cooking has become a lot simpler now that she’s not afraid to use fat, as it adds so much flavour to foods such that not much seasoning is required. These days, she eats twice as much vegetables, and her dinner could comprise just a steamed head of broccoli cooked in butter, topped with a dash of salt or garlic.
Ms Cheah explains that a lot of people who are on the keto diet to lose weight tend to also do it together with IF, which she has tried as well. She believes that keto and fasting are more effective than other diets such as the gluten-free diet or the leptin diet, which she had tried previously but to no avail. A leptin diet requires one to limit carbs and eat a high-protein breakfast, among other things. However, Ms Cheah noticed that she quickly packed on the pounds within a week or two of trying it.
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For Ms Cheah, a combination of fasting and the keto diet – which she says is not difficult to follow – has made her a healthier eater. She also believes that such dieting regimes are more holistic and sustainable than merely taking protein shakes as meal replacements.
Ultimately, one should still have the joy of food, she adds. “The biggest change for me really is that it has changed my approach to food in a massive way, and I hope that continues.”
A fitness coach who graduated with a Sports Science degree from the University of Queensland, Mr Lee cut carbs and went on a keto diet initially to lose weight, but soon found this unsustainable as he would feel tired during workouts. A conversation with his cousin sparked his interest in IF, and he decided to give it a go. It’s been two years since he first started on the 16/8 diet, and the rest, as they say, is history.
“What drew me into IF was that you could enjoy your food, but if you ask me whether I could maintain a keto diet in the long term, I don’t think I could because you lose out the simple joy of going out to have a meal with your friends.” He adds that while fasting may be daunting at first, once it becomes a habit, it is pretty much “fuss-free”. “Actually if you break it down, it just means you’re skipping a meal; in this case I’m skipping breakfast, and to be honest it’s not a very hard thing. In fact I don’t even think of the fact that I’m doing IF, it’s become so natural it’s like a lifestyle.”
He now recommends his clients to complement their workouts with IF, but doesn’t insist that they do so. “For me it’s more about performance, whether I can still sustain my intensity of workouts with IF, and yet not worry about what I eat.”
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However, Mr Lee also points out certain caveats: for women, fasting may interfere with their hormone cycle; and generally one should still watch what they eat with IF, especially if they want to get their metabolic rate up.
“IF works for me, but ultimately everyone’s body is different. Listen to your body and adjust accordingly; some people skip dinner instead of breakfast… At the end of the day, find what suits you, and go with it. You want to be in control, instead of being controlled,” he concludes.
Indeed, studies have shown that IF can bring about health benefits including a reduction in blood pressure and inflammation, and seems to be good for one’s cardiovascular system.
Fasting also makes sense from an evolutionary standpoint. 24/7 access to food wasn’t available in the past when sustenance was harder to come by. Ancient hunters didn’t have supermarkets, refrigerators or food available all year round; there were times when they couldn’t find anything to eat. As such, humans evolved to be able to function even without food for extended periods of time.
But while some experts may be optimistic about IF, others acknowledge that there are still many unknowns. In fact, a recent study released by The American Journal of Clinical Nutrition found that IF is no better than conventional dieting for weight loss.
senior principal dietitian and head of
the Nutrition and Dietetics department at Tan Tock Seng Hospital
According to Dr Lim, though small-scale studies have shown benefits of the keto diet and IF, the long-term effects of these regimes remains to be seen. While research has shown that the keto diet may bring about short-term benefits such as weight loss and an improvement in blood sugar and cholesterol over 12 weeks or less, it is challenging for individuals to maintain this diet due to the disproportionate distribution of fat and carbs, she notes.
Similarly, the long-standing impact of IF is unclear, says Dr Lim. “As people are more mindful of their food choices and are keen to make dietary changes, that is a positive sign as it means that they are motivated and empowered to make changes to their lifestyle. Subconsciously, they may have also cut down on their overall intake and consume less calories as a result of being on these diets, even though these diets do not claim to be calorie-restrictive.”
“They will then experience some initial weight loss, which provides a positive reinforcement that these diets are effective for them.”
Nonetheless, she cautions that the applicability of these diets to people with various health conditions is ambiguous, especially among those with liver or kidney problems. “People with Type 1 diabetes, those who are pregnant, elderly, or adolescent, are not suitable. Some other side-effects of long-term ketogenic diet include high uric acid level in blood, osteoporosis, and kidney stones,” she says.
Yet another issue with the keto diet is that it does not specify the proportion of unsaturated to saturated fats in meals. As such, it is possible for individuals to consume excessive high-saturated fats that can adversely affect cardiovascular health, Dr Lim says.
Separately, those taking medication for diabetes, pregnant women, people with eating disorders and children or adolescents should not consider trying IF, Dr Lim explains. She adds that both diets are generally not recommended to people who are keen to lose weight, as they may be restrictive and not sustainable.
As the dietitian puts it: “Individuals may experience uncomfortable feelings that can affect their mood, fatigue, headaches. If it is not well-planned, those on keto diet may develop certain nutrient deficiencies if a wide variety of food is not included. For IF, it is still important for the food choices to be healthy and nutritious during non-fasting periods.”
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On that note, Dr Lim highlights that it’s important for people to appreciate that in order to achieve long-term weight loss, one will need to couple healthy diet choices with increased physical activity, while enjoying a variety of food in suitable portions. For sustained weight loss, she adds, one will need to adopt “lifestyle and behavioural changes” that can be adhered to in the long run, instead of seeking quick-fix solutions.
It’s not just people with some excess kilos who have a keen interest in dieting. Tech startups, in a bid to cash in on the latest health crazes, also have their sights on the industry – for good reason. Research firm Marketdata LLC valued the 2017 US weight loss market at US$66 billion, while Stratistics Market Research Consulting (MRC) noted that the global weight loss and weight management market accounted for some US$169 billion in 2016. Citing huge opportunities presented by the surge of childhood obesity, Stratistics MRC projects that the sector will be worth a whopping US$279 billion by 2023.
Interestingly, monthly Google searches for the phrase “intermittent fasting” have surged 10 times over the past three years, with as many as one million hits per month, a Bloomberg article noted. That’s as many searches as “weight loss” gets, and rather more than the term “diet” itself. According to the article, fasting routines are gaining traction in Silicon Valley, in part because they are framed not just for weight loss, but to boost productivity as well.
Apparently there’s growing research linking periods of non-eating with greater mental focus, or perhaps a longer life span. As Peter Attia, a physician who specialises in the science of longevity notes, periods of nutrient restriction can do good for our bodies. “The subjective benefits are evident pretty quickly, and once people do it, they realise – if this is going to give me any benefit in my performance, then it’s worth it,” he explains.
For instance, personalised meal-planning company, PlateJoy, designed an app to help users stick to a healthy diet. As part of a diabetes prevention programme, about 20 million people with pre-diabetes in the US have free access to the app via their health insurer. Among other things, subscribers will take a quiz featuring questions including dietary preferences and time constraints. The app’s algorithm then uses these results to choose from recipes in its database to design a customised meal plan with the ingredients required.
Co-founder and CEO Christina Bognet, a MIT-trained neuroscientist, says the plan encourages time-restricted food intake – that is, eating within a particular window of time each day. Doing so has enabled her to keep off the 23kg she has lost in recent years, she says. Her five-year old company is profitable, and is looking to raise even more venture capital to supplement early funding from incubators such as 500 Startups and Y Combinator.
Another example of a startup riding on the dieting bandwagon is HVMN (read “human”), one of the first companies to bring to market a ketone ester drink. While founders Geoffrey Woo and Michael Brandt were mocked at on the set of Shark Tank back in 2016, the firm appears to be doing well after it rebranded itself and introduced the new drink as a way to enhance cognitive function and optimise performance, especially for athletes. The drink contains 120 calories, and has no fat, protein or carbs, but is said to taste like nail polish remover and costs US$33 per serving. HVMN has since garnered more than US$5 million from venture backers, including former Yahoo! CEO Marissa Mayer.
Similarly, The Atlantic writer Amanda Mull notes that the Valley is creating a whole new cluster of products that could alter the language of dieting and, in turn, how people think about their bodies. Instead of merely eating salads, more people are now seeking to “biohack” their personal ecosystem, she says.
“Dieting is no longer a necessary problem of vanity, as it has been historically termed, but a problem of knowledge and efficiency – a rhetorical shift with broad implications for how people think of themselves. Where bodies might have previously been idealised as personal temples, they’re now just another device to be managed,” Ms Mull adds.
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This article was originally published in The Business Times.
Header Photo/Illustration: BT/SPH