Welcome to Ask Doctor Zac, a weekly column from news.com.au. This week, Dr Zac Turner shares the benefits of a controversial weight loss method.
QUESTION: Hi Dr Zac, intermittent fasting has exploded in my local gym! It’s the only thing people are talking about, and it all started because this new PT started rocking up and telling their clients to starve themselves for 12 hours each day.
I think it’s all a bit fishy, but I want to check with a real health professional first. Does intermittent fasting actually work, or is it teaching yourself bad habits? – Karina, 34, Queensland
ANSWER:Intermittent fasting has actually been around for quite some time, but I appreciate you have attempted to get a second opinion. I always love it when people have their thinking caps on, and bull-crap detectors tuned, when they hear new health information.
Believe it or not, but the PT in your gym is actually on to something! I’ve read about, and tried, a fair few fad diets in my day but intermittent fasting is one that I believe can work for most people.
It’s a weight loss strategy I often give to my patients. You could eat a healthy, balanced diet for five days but have two days of fasting where you eat very little food. This process essentially shocks your body’s metabolism, speeding up the weight loss process.
Additionally, intermittent fasting promotes the production of the hormone norepinephrine. This hormone promotes body fat to be broken into free fatty acids, which can in turn be burned for energy.
It’s essentially a flexible eating pattern that involves cycling between periods of not eating (fasting) and eating. The frequency can depend on your own lifestyle, which is why it works for so many people. Some people decide to only eat at the office between 9-5pm, and others simply decide to skip breakfast.
It’s not about what you eat, but when you eat! Some people decide to combine intermittent fasting with calorie restriction to lose more weight, but I recommend you start slowly first and ease into that.
Here are two common approaches:
Daily intermittent fasting
This involves fasting for a portion of each day and eating during a specific window of time. The most popular daily fasting method is the 16/8 method, where you fast for 16 hours and restrict your eating to an eight-hour window. For example, you might skip breakfast and eat your meals between 12pm and 8pm. This approach is typically repeated every day.
Weekly intermittent fasting
With this approach, you may choose to fast for a full 24 hours once or twice per week. For instance, you might fast from dinner on Monday until dinner on Tuesday, or from dinner on Tuesday until dinner on Wednesday. On non-fasting days, you eat normally.
Both of these methods can help with weight loss, improving metabolic health, and simplifying your meal plans.
You may feel hungry, weak and have brain fog when you begin to intermittent fast. This can be temporary as your body gets used to the new system.
This isn’t a one-size-fits-all health plan, however, and I would steer clear of any PT who doesn’t take a personalised approach for each of their clients.
Got a question? Email askdrzac@conciergedoctors.com.au
Dr Zac Turner has a Bachelor of Medicine and Bachelor of Surgery from the University of Sydney. He is both a medical practitioner and a co-owner of telehealth service, Concierge Doctors. He was also a registered nurse and is a qualified and experienced biomedical scientist along with being a PhD Candidate in Biomedical Engineering.