Is this the ‘fast’ track to better health and wellbeing?

Intermittent faster and author Gin Stephens reveals how intermittent fasting transformed her life, and how scientific evidence points to its benefits, writes Natalie Li.

“I’ll never stop because it feels so good,” says Gin Stephens, (pictured), as she sips on her first black coffee of the day in a joyful-looking festive mug. The best-selling New York Times author and podcast host is raving about the intermittent fasting (IF) lifestyle she has embraced since 2014.

Stephens, a long-time yo-yo dieter, hit a low moment after seeing what she considered unflattering photos of herself from a family cruise. She tried the keto (ketogenic) diet but found it restrictive and ineffective. The breakthrough came in 2014 when she turned to intermittent fasting.

“I decided, all right, it’s time to do something after I’d dabbled in various diets,” she explains, “so I tried IF and went on to lose 80 pounds and I’ve been living that way ever since.”

Stephens begins her day with a black coffee and fasts until 2pm; then she opens what she calls her “eating window” for a small lunch or breakfast, followed by a shorter break and then a ‘clean’ dinner with her husband at 7pm.

This five-hour eating window has worked wonders for her. “A lifestyle that I could really do forever.”

What is IF?

Intermittent fasting is an eating plan or pattern that switches between fasting and eating on a regular schedule. Research shows that intermittent fasting is a way to manage your weight and prevent diseases.

“Our ancestors didn’t have constant access to food and their bodies adapted to use stored fat for energy,” says Stephens. “Modern diets with constant snacking keep our bodies in ‘storage mode’ and hinder fat burning.”

“IF offers numerous health benefits beyond weight loss. By understanding insulin’s role in metabolic health, we can appreciate how IF can positively impact our well-being. Insulin, often associated with diabetes, plays a crucial role in regulating blood sugar levels,” explains Stephens.

However, modern diets, filled with frequent meals and sugary drinks, can lead to insulin resistance, she says.

Stephens adds: “Intermittent fasting helps to improve insulin sensitivity by reducing insulin levels, allowing your body to tap into stored fat for energy. This can lead to weight loss, improved blood sugar control, and a reduced risk of chronic diseases.”

Researchers like Dr Mark Mattson, an expert in ageing and neurodegenerative diseases, have extensively studied the benefits of intermittent fasting. Mattson’s research highlights the positive impact of IF on brain health and cognitive function. Studies such as the Big IF Study have also shown that even short periods of intermittent fasting can lead to improvements in metabolic health, weight loss, and cognitive function.

But not all research has been positive.

News outlets reported on a non-peer reviewed study published earlier this year that suggested people who limited their eating window to less than eight hours a day had a 91 per cent (almost double) increased risk of dying from heart and circulatory diseases, compared to those who had a more typical eating window of 12 to 16 hours.??

The British Heart Foundation’s verdict on the study, and Stephens agrees, is that more research is needed to draw firm conclusions about the long-term effects health effects of intermittent fasting.

Starting IF

There are a few different intermittent fasting strategies. Time-restricted feeding is when fasters limit eating to a window of a few hours per day — typically between eight and 12.

Alternate day fasting involves switching between a ‘fast day’ (no food or less than 25% of ‘normal’ intake) and a ‘feast day’ (as much food as the faster likes).

And finally, there’s periodic fasting, or whole day fasting, which is any period of consecutive fasting for more than 24 hours. It could be a single day or several weeks of continuous fasting.

In her book 28-Day Fast Start Day-by-Day: The Ultimate Guide to Starting (Or Restarting) Your Intermittent Fasting Lifestyle So It Sticks, Stephens suggests a 28-day “fast start” to help your body become metabolically flexible.

She also says that clean fasting is the way forward. This means avoiding food, sugary drinks, and creamy tea or coffee. She advises avoiding artificial sweeteners or flavours, cream, milk, bone broth or protein. So, what can you have? “It’s best to stick to plain water, sparkling water, black coffee and plain tea,” she says.

Rosie Letts, nutritional therapist and functional medicine practitioner, advises: “For beginners, I often recommend starting with a gentle fasting schedule, like the 12:12 method (12 hours of eating and 12 hours of fasting), then gradually working towards a 16:8 window. This allows your body to adjust to longer fasting periods without causing stress.

“IF can be effective for weight loss as it encourages mindful eating within a defined window, often reducing the tendency to overeat. However, it’s crucial to listen to your body,” she adds.

“IF may suit you if you find structured meal timing helpful and don’t experience energy dips. If you have health concerns or a history of disordered eating, consult a healthcare professional before beginning.”

What can you eat?

Nutrient-dense foods are ideal for the eating window, suggests Letts.

“Prioritise lean proteins, healthy fats, and plenty of vegetables to keep energy levels stable and support metabolic health. Think of meals with balanced macronutrients like a protein-rich salad with mixed greens, avocado and a source of healthy fats, or a hearty bowl with quinoa, veggies, and grilled chicken. Snacks like Greek yoghurt, nuts or fruits can also help with satiety.”

Improved sleep

Intermittent fasting may help people who have irregular sleep patterns or insomnia due to the limitation of food intake in the evening, which helps to restore the internal body clock. Just as the circadian rhythm relies on sunlight to stay regulated, food also plays a vital role. Following set mealtimes, like in intermittent fasting, can help reinforce the natural circadian rhythm, explains Zoe Gotts, a clinical psychologist in behavioural sleep medicine.

On the flipside, fasting can also cause issues with sleep, depending on the timing of meals. For example, when people eat at irregular times, sleep can be disrupted and quality of sleep negatively impacted. This is particularly problematic if we eat late at night because it raises body temperature and can play havoc with digestion.

“Scheduling your last meal around three hours before bed, and limiting caffeine and alcohol is crucial,” she advises.

“Caffeine can decrease appetite, but it also disrupts sleep. Alcohol disrupts both sleep and metabolism. Stick to nutrient-rich, whole foods and limit processed and high sugar foods. Foods that are nutritious are good for sleep as well as your diet.”

Gotts adds: “Ensure you are practicing healthy sleep habits. Ensuring a cool, dark, and quiet sleep environment is important. When you’re hungry, the stress hormone cortisol rises. Cortisol affects sleep quality. This makes it important to prioritise stress management. Regulate your stress levels and give yourself enough time to wind down in the evenings.”

Side effects to IF and how to manage them

It’s common to experience initial side effects like fatigue, irritability or headaches as the body adjusts. These often improve as your metabolism adapts to the new schedule. “Staying hydrated, easing into fasting, and ensuring you have nutrient-dense meals during the eating window can help minimise these effects. If side effects persist, you may need to try a shorter fasting period,” adds Letts.

Who shouldn’t do intermittent fasting and why?

Certain groups should approach IF with caution or avoid it altogether, cautions Letts. “Pregnant or breastfeeding women, individuals with a history of eating disorders, those with chronic stress or sleep disorders, and people managing specific health conditions (e.g. diabetes) should consult a healthcare professional. These groups may have unique needs that don’t align well with IF, and restrictive eating patterns could risk disrupting their health.”

Letts adds that women and men can experience fasting differently due to hormonal fluctuations. “Women’s hormonal cycles, especially the menstrual cycle, play a role in how the body responds to fasting. I recommend that women adapt fasting around their cycle, with more flexibility during the luteal phase when the body often needs more calories.

“Women should also be cautious with extended fasting, as overly restrictive schedules can impact menstrual regularity and hormone health.”

There’s no doubt intermittent fasting can be a powerful tool for weight loss, improved metabolic health and overall well-being. However, it’s clear a personalised and thoughtful approach should be taken, while consulting a healthcare professional if needed.