Nutrition talk lately seem to be full of numbers: 16:8, 14:10, 5:2. If these ratios sound familiar, you’ve probably already heard about intermittent fasting (or “IF”). Celebrities like Terry Crews, Chris Pratt and Halle Berry have all given IF a try. But what about the rest of us?

At Centr, our approach is to enjoy delicious food regularly over the day, according to your individual needs, preferences and lifestyle. After all, the best healthy eating meal plan is the one that fits with you: if it disrupts your life too much, chances are you won’t stick with it. But we get it: you’re curious about an eating style that’s getting as much celebrity buzz as IF, so we’re here to give you the lowdown.

What’s the deal with IF?

IF takes a number of forms, the most common being the 5:2 and 16:8 modes. In the former, you eat a regular intake for five days of the week and significantly restrict your caloric intake for two non-consecutive days, while in the latter, you do all your “daily eating” (so, your entire standard daily caloric intake) within an eight-hour window and fast for the remaining 16 hours. The proposed benefits of fasting are wide-ranging, with a primary focus on weight loss, but research also indicates benefits for particular chronic health conditions like diabetes and a positive impact on longevity when it has been prescribed by a medical professional.

Why is it so popular?

Everybody wants that magic formula to achieve their goals, and the anecdotal evidence, along with a few studies, can suggest that IF is the ticket to pushing through your weight loss and training plateaus. When you couple that with the famous bodies we’ve heard use IF as part of their health and fitness arsenal, that’s going to sound pretty attractive. The 16:8 mode is especially popular because it isn’t a “diet” in the traditional sense: when you’re within the eight hours of feeding, you eat normally. If you’re sick of diets of endless cabbage broth or ‘detox’ juices, the prospect of eating a regular sandwich or bowl of pasta can sound practically heavenly.

Where should you begin?

So you’ve read a few blogs, chatted with your friends who’ve tried IF, you’re ready to go, right? Not so fast! If you’re thinking of trying IF, ensure you are making nutrition choices that meet your specific needs, and that you consult with a health professional or dietician for individual advice. They can create a plan for you to start safely. You’ll know quickly if you’re not into it!

When it’s definitely not for you

There are some people who should give IF a miss. If you have a medical condition or take medications that require regular intake of food, have a history of disordered eating or a diagnosed eating disorder, or if you are pregnant or breastfeeding, IF is not for you. Also, though you may have heard people talking about IF helping their gut issues, if you have a tendency to become constipated, you may find IF makes it worse.These are two approaches to the 16:8 – one of the most popular fasting methods.

What the science suggests

Initial clinical studies indicate that there are benefits to IF, but that they aren’t “magic bullets” just yet. A 2018 study by the German Cancer Research Center (DKFZ) and Heidelberg University found that while IF helps people lose weight and promotes health, it’s not superior to more traditional calorie-restricted eating plans when it comes to weight loss.

What about other benefits?

Researchers at University of Adelaide conducted small, short-term studies that found time-restricted feeding showed improvements in some markers for diabetes, like levels of blood glucose levels and appetite hormones. Studies employing mice and rats have indicated that IF may have anti-ageing benefits, but scientists have cautioned we’d have to wait more than a century to see if it had similar results in humans.

“Weight loss” can also mean muscle loss

When we talk about wanting to lose ‘weight,’ we usually mean that we’re trying to reduce body fat, but IF can lead to loss of body weight in general, and that can mean muscle loss as well as fat loss. If you are trying to build muscle, the timing and total amount of food you’re able to consume may be inadequate. In other words, if your morning weights session falls outside of your 16:8 “eating window”, you won’t be refueling and feeding muscle growth until well after a workout.

Is it sustainable long term?

Not enough studies have been undertaken in order to make a call either way, but most dieticians and scientists seem to agree currently that prescribed IF can be a useful tool to employ occasionally when other methods have plateaued. It’s worth remembering that if you are training at a decent level and training results are your goal, then IF may not provide the right timing of food intake for optimal performance outcomes.

Still undecided?

It’s important to remember that even though it’s popular, IF is not necessary for everyone to achieve their desired health and weight loss outcomes. Whether you’re trying to lose weight or gain muscle, nutrition should support your fitness journey or else that hard work goes out the window. IF works for some people, and that’s okay, so think about it like any other health and fitness regime: you might be a tried-and-true weight-training person, while your friend might prefer lots of cardio. While you might both be getting great results, it doesn’t mean you have to adopt the other’s routine.