The term “intermittent fasting” has become part of everyday vernacular over the past few years. Whether it’s the 16:8 method (fasting for a 16-hour window, eating within the remaining eight), or the 5:2 approach (reducing your calories to around 500 on two days of the week, and eating normally on the other five), time-restricted eating—or abstaining from eating during certain hours—is a popular way to manage weight, look after our digestive systems and feel focused, energized, happier and healthier.
But a new study published last week prompted headlines questioning the efficacy of the popular technique—specifically when it comes to weight loss. The study’s aim was to determine whether time-restricted eating proved more effective for weight control in 90 obese (and, it’s worth noting, diverse) adults than calorie restriction, the more traditional method of weight management.
While the time-restricted eating group consumed fewer calories per day than those in the calorie-restricted group, they lost less weight (10 lbs versus 12 lbs) over the year. The results—which come as a reported 37.3 million people in the U.S. are living with diabetes—suggest that calorie-counting is a more effective method to achieve and maintain a healthy weight than intermittent fasting. We asked an expert for their take on the study, and on how well the technique actually works.
Calorie counting vs. intermittent fasting
“From a scientific perspective—and taking into account my experience from years of clinical practice—intermittent fasting is better for your health than caloric restriction,” says Rhian Stephenson, nutritionist, naturopath, and founder of Artah. “But this study points out important themes that are key for overall health, namely the importance of food quality and fiber.”
While the study was an investigation into which diet structure is better for weight loss, there was no focus on—or monitoring of—the quality of the food that the two groups were consuming. Participants were allowed to eat freely and, as Stephenson points out, sugar-free beverages (which disrupt the microbiome) were actively encouraged to help participants keep their calorie intake down.
“Both groups averaged half the daily recommendation for fiber intake, were on fairly high carbohydrate diets, and were ingesting three times the recommended daily allowance for sugar,” she says. “Diet structure will only take us so far, regardless of whether you’re reducing your daily calories or trying intermittent fasting. The most important thing we can do is eat a diverse range of good quality food, rich in fiber and low in sugar. This, in combination with intermittent fasting, will give you the most beneficial change in hormones and set the stage for great health.”
The reality of calorie counting
While we’ve long been programmed to believe that the secret to maintaining a healthy weight is to ensure the number of calories we ingest is equal to the amount of energy we expend, the science world is pivoting to focus on other metrics—think blood sugar levels—for a healthy body (and mind).
“Studies have shown, time and time again, that whilst periodic or short bouts of calorie restriction can result in fat loss and metabolic improvements, prolonged calorie restriction just doesn’t work,” says Stephenson. “Our bodies have the incredible ability to adapt—when we restrict calories for a prolonged period of time, hormonal mediators of hunger will increase, which usually leads to increased cravings.”
If we continue to count calories and our body weight drops, we end up having to lower our calorie intake even more to continue to lose weight. This can then lead to an increase in the stress hormone, cortisol, changes to the immune system and hormone balance, alongside a loss of lean muscle mass, which is crucial for good metabolic health. Nutritional deficiencies are also not uncommon.
If you’ve ever tried calorie counting, then you’ll know it’s not without its emotional difficulties either—particularly if you do it for a prolonged period of time. “It often leads to discontent, social withdrawal, being overly fearful of food and, of course, rebound periods of bingeing when it all becomes too stressful,” says Stephenson. “It’s generally not a very joyful way to eat, and enjoying food is one of life’s great pleasures.”
The health benefits of intermittent fasting
Which brings us back to intermittent fasting. Contrary to the findings from the research, time-restricted eating is backed by myriad scientific papers that suggest it’s actually a very good way to manage our health, weight levels, and general wellbeing. “It has been shown to benefit the gut microbiome (and overall gut health),” says Stephenson. “It allows the essential digestive rest that our microbes need to restore themselves and remain healthy, generally helps reduce total insulin exposure in the body, and allows a number of physiological processes to run more smoothly too.”
She references a 2011 study in the Journal of Obesity, which compared two groups—one which followed daily calorie restriction, and the other that implemented two intermittent fasting days a week—over six months. While both groups experienced similar weight loss and improvements in inflammation, oxidative stress, and blood lipid markers, the intermittent fasting group showed a greater improvement in insulin resistance, making it a great way to manage blood sugar levels.
How to introduce intermittent fasting and improve your diet
While there are a number of different approaches to time-restricted eating, it’s best to start slowly and gently. “Try shortening your eating window to between eight and 10 hours for three days a week to start with,” suggests Stephenson. “The best way to do this is to enjoy a solid, balanced breakfast and reduce your evening portion on those days.” She recommends eating a nutrient-dense soup early in the evening—with or without a side of simple protein, such as grilled chicken or fish. Of course, many who employ the method opt to skip breakfast and eat between the hours of 10 a.m. and 6 p.m., for example.
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Once you’ve got this down, the next step is to focus on the quality of the food you’re eating. “Cut processed sugar and increase your intake of protein and fat to ensure you feel satiated,” she says. “From there you can build at a pace you’re comfortable with. Increasing the plant diversity in your diet, going for a walk after meals, and adding in more strength training can all help.” For those who need some extra guidance, seek out a program like Artah’s The Metabolic Reset to give you structure and support through the process.
Food is medicine, and the ways in which we consume our food impact not just our weight—as this recent study explored—but how we feel. So load up on plants, healthy whole foods, eat mindfully, and do so at times that work for you and your routine.