What are the pros and cons of intermittent fasting?
Intermittent fasting has become extremely popular in recent years as a way to lose weight, and is a method favoured by a number of celebrities, including Hugh Jackman, Cameron Diaz, Jennifer Aniston, Kourtney Kardashian, former prime minister Rishi Sunak, and more.
Unlike traditional diets, which focus on what you eat, intermittent fasting focuses on when you eat, cycling between periods of eating and fasting.
The late Dr Michael Mosley was a major advocate for intermittent fasting and his approach, called Time Restricted Eating, became hugely popular in the UK.
He previously explained his method and said: "The key is to have dinner earlier and breakfast later, thereby giving your body a short overnight fast.
"Encouraging results have been found for overnight fasts between 12 to 14 hours long, but experts suggest that even just simply pushing back breakfast and bringing forward dinner by an hour each way, your body is likely going to feel the benefits."
While some - like Dr Mosley - swear by its benefits, others remain cautious about its long-term effects. Recent studies provide valuable insight into the potential pros and cons of this eating pattern.
What are the pros of intermittent fasting?
Weight loss and fat reduction
Studies suggest that intermittent fasting can help reduce body fat and promote weight loss. When you fast, the body goes into a state of ketosis (fat burning), leading to more efficient fat metabolism.
A study published in Obesity Reviews in 2021 concluded that intermittent fasting can be as effective as traditional calorie restriction for weight loss. Research also shows that IF helps to reduce visceral fat, which is linked to higher risks of metabolic diseases..
Improved insulin sensitivity
It has been suggested that Intermittent fasting can improve insulin sensitivity, which helps the body regulate blood sugar levels more effectively.
This is particularly important for people at risk of developing Type 2 diabetes. A 2020 study in Cell Metabolism demonstrated that fasting for 16 hours a day helped participants lower their blood sugar levels and improve insulin sensitivity without the need for medication.
Brain health and cognitive function
Research on intermittent fasting’s effects on the brain has shown promising results. The fasting period triggers the production of brain-derived neurotrophic factor (BDNF), a protein that supports the survival and growth of neurons.
A 2021 study in Nature Reviews Neuroscience found that intermittent fasting improved cognitive function, neuroplasticity, and could even reduce the risk of neurodegenerative diseases like Alzheimer's.
Increased longevity and anti-aging benefits
A growing body of research suggests that intermittent fasting may increase lifespan by reducing oxidative stress and promoting cellular repair processes. Studies in animals have shown that fasting can extend life expectancy, and human studies are beginning to show promising results as well.
A 2022 study published in Science Translational Medicine indicated that intermittent fasting increased markers of longevity and reduced markers of aging, such as inflammation and oxidative stress.
Simple to follow
One of the biggest advantages of intermittent fasting is its simplicity. Unlike traditional diets that require constant meal planning, calorie counting, or eliminating food groups, IF simply requires time-restricted eating. Many people find this more sustainable over the long term because it doesn’t require drastic changes to food choices.
What are the cons of intermittent fasting?
While intermittent fasting offers several benefits, it’s not without its drawbacks. Here are some of the common downsides reported in studies and personal experiences:
Potential for overeating during eating windows
One of the key risks of intermittent fasting is the temptation to overeat during the eating windows. Some individuals may find themselves consuming more calories than they would if they were eating regularly throughout the day, which could negate the benefits of fasting. A
In 2021, scientists found that some participants gained weight or failed to lose weight while practicing intermittent fasting due to excessive caloric intake during eating windows.
Possible negative effects on women’s hormonal balance
For some women, intermittent fasting can disrupt hormonal balance, particularly during menstruation or in women with polycystic ovary syndrome (PCOS). A 2022 study found that prolonged intermittent fasting may interfere with menstrual cycles and lead to an imbalance in reproductive hormones, which could affect fertility.
Risk of nutrient deficiencies
Because intermittent fasting restricts the time available for eating, there’s a risk of not getting enough nutrients, especially if meals are not well-balanced. A 2021 study in Nutrients found that people practicing IF without proper meal planning were at an increased risk of deficiencies in important vitamins and minerals, such as calcium, vitamin D, and magnesium.
Watch: How to start intermittent fasting safely
Possible increased stress and anxiety
Some people report feeling stressed or anxious about fasting, particularly during the early stages when the body is adjusting to longer periods without food. In a study published in Psychology & Health, researchers found that participants practicing intermittent fasting experienced increased anxiety and irritability, especially when fasting for extended periods.
Not suitable for everyone
Intermittent fasting may not be suitable for people with certain medical conditions, including eating disorders, low blood pressure, or those who are pregnant or breastfeeding. In fact, experts recommend that individuals with a history of eating disorders should avoid restrictive eating patterns altogether. It’s always important to consult a healthcare provider before beginning any fasting regimen.
Should I try intermittent fasting?
Intermittent fasting can offer impressive health benefits, from weight loss to improved metabolic health and potential longevity. However, it is not a one-size-fits-all approach. While some people thrive on it, others may face challenges such as nutrient deficiencies, hormonal imbalances, or increased stress.
Ultimately, whether intermittent fasting is right for you depends on your health goals, lifestyle, and how your body responds to the fasting regimen. As with any lifestyle change, moderation and balance are key.
Before embarking on any change in your diet, you should consult your GP and discuss what options may be best for you.
Read more about weight loss:
Alison Hammond reveals why she is 'frightened' of weight loss medications (Yahoo Life UK, 3-min read)
Josie Gibson's six stone weight loss after making one vital change to her diet (BristolLive, 5-min read)
I'm a fitness expert and this is the truth about carbohydrates and weight-gain (Liverpool Echo, 3-min read)
