How fasting cycles can boost your immunity

Confused about the connection between fasting, health and immunity? Here’s what you need to know.

There’s the 16:8, the 5:2, the Fast 800 (Michael Mosley), alternate-day fasting, the Eat Stop Eat fast (Brad Pilon) and even the Warrior Diet (Ori Hofmekler), where you eat small amounts of fruit and vegetables during the day and one huge meal at night.

Yes, the amount of advice about fasting circulating on the internet and our social media feed can make life confusing for mere mortals.

After all, not all of us have a degree in science and/or nutrition, which is why we checked in with the experts to get the lowdown on how fasting might help our immunity, if at all.

What does the science say on fasting?

A University of Southern California study found fasting lowers white blood cell counts, which triggers the immune system to start producing new white blood cells (they’re the ones that fight off infection).

The researchers concluded that cycles of prolonged fasting might not only protect against immune system damage but can also induce immune system regeneration, shifting stem cells from a dormant state to a state of self-renewal.

While that study looked at longer periods of fasting, research published in the New England Journal of Medicine found you can get many of the same immune-supporting benefits with time-restricted fasting.

The study’s authors concluded that eating in a six or eight-hour window every 24 hours can trigger a metabolic switch from glucose-based to ketone-based energy, resulting in increased stress resistance, increased longevity and a decreased incidence of diseases.

How does that translate to real life?

Dietitian and 16:8 Intermittent Fasting author Jaime Rose Chambers says she uses a variety of intermittent fasting routines with her clients with positive results.

“Like any lifestyle intervention, it’s not for everyone and it’s important to match a particular method of fasting with a particular person, but the research on the health benefits of immunity fasting is pretty spectacular,” Jaime says.

“As an evidence-based practitioner, I’ve certainly been able to take it on as a dietitian and, while the main drawcard is weight management, there’s a roll-on effect because when you do lose weight your blood cholesterol and blood pressure goes down, your inflammatory markers go down, your insulin sensitivity improves, you sleep better,” she says.

Dietitian and Australian Healthy Skin Diet author Geraldine Georgeou says if you are considering fasting, it’s important to think it through.

“As with any dietary approach, you need to consider whether this is something you can keep to in the short and long term — think about how not eating for a period of time might impact you physically and emotionally, and how it will impact your family,” Geraldine advises.

How do you get your fast on?

The 16:8 and 5:2 are two of the most popular fasting methods, Jaime says. She explains how they work.

  • Time-restricted, or 16:8: “The research shows the best timeframe to eat is between 10am to 6pm, or 11am to 7pm,” Jaime says.

Eat during this window and fast for the other 16 hours, and do this every day.

  • 5:2 fasting: Fast for two different days each week, which for women means limiting their total intake to 2100 kilojoules and men to 2500 kilojoules (which is about 25 per cent of the recommended intake for normal-weight adults).
    “The 5:2 can be difficult, which means the drop-out rate can be high,” Jaime says.
    “Whereas I’ve found that even personally the 16:8 approach can become a daily philosophy and a way to live your life with very good results.”

“Just make sure if you are fasting that the food you’re eating is a balance of healthy fats, good lean proteins, lots of fibre and plant-based foods and see a health professional first for guidance as to what pattern of eating will work best for you,” Geraldine says.

Written by Liz McGrath.