1,383 words, 7 minutes read time
Updated on April 13, 2024. Fact checked by Robert Underwood, Head of Research
Intermittent fasting has become hugely popular. Hugh Jackman, Jennifer Anniston, Halle Berry, and Kourtney Kardashian have all been vocal about its benefits and we’ve all seen the incredible results they’ve achieved.
But it turns out that intermittent fasting isn’t just another trendy celebrity fad. There’s the science that backs it up too. Plus, this type of fasting is a whole lot easier than many other restrictive eating plans. While intermittent fasting does include calorie restrictions at certain times of the day or week, it’s not about starving your body of essential nutrients.
In fact, there are certain foods and supplements that can be eaten during fasts to sustain the fasting state without leaving you hungry, dehydrated, or lethargic. You can benefit from intermittent fasting while consuming many of your favourite drinks, foods, and sweeteners, as long as you choose them carefully.
Here’s everything you need to know about intermittent fasting and what you can consume while playing by the rules.
Intermittent Fasting Defined
According to Johns Hopkins Medicine, intermittent fasting is exactly what the name describes.
Intermittent fasting is an eating plan or dieting method that alternates between periods of fasting and periods of typical eating. This method is widely used to improve insulin sensitivity, promote a state of ketosis to burn more fat and stimulate autophagy and the new turnover of cells.
The respected medical faculty notes that plenty of research has proven intermittent fasting’s ability to help you manage your weight and prevent, or even reverse, certain diseases and metabolic disorders.
For example, a 2020 study published in the New England Journal of Medicine notes that the state of ketogenesis induced by periods of fasting can improve blood glucose levels and regulation, reduce inflammation throughout the body, promote sustainable weight loss, and even increase your resistance to stress during both fasting and non-fasting periods.
How Do You Practice Intermittent Fasting?
Johns Hopkins neuroscientist Mark Mattson says that there are a few different ways to perform intermittent fasting. However, all of them are based on regular time periods of eating and fasting.
There are time-restricted methods like the 16-8 method, in which you only eat during an 8-hour window each day, and alternate-day methods, during which you will only fast for a few days a week or on every alternate day.
Find out more about the types of intermittent fasting.
According to Mattson, after your body has gone without food for a few hours, it will exhaust its stores of sugar and start to burn fat stores for energy instead. This process occurs through a state known as ketosis, which Mattson also refers to as metabolic switching.
Intermittent fasting requires you to prolong the periods during which your body has burned through the calories you eat at mealtimes, encouraging it to burn fat instead of eating calories alone.
How is Intermittent Fasting Different to Keto?
As we explained, intermittent fasting is an eating pattern that alternates between calorie-restricted fasts and regular food consumption.
The ketogenic diet, or ‘keto’ diet, is a method of eating that restricts your carbohydrate intake and requires you to eat large amounts of fat instead.
In the keto diet, dieters reduce their carbohydrate intake to 20-50g per day. This forces their bodies into a state of ketosis to produce ketones that are used for fuel in place of glucose. During ketosis, the body breaks down fats into ketones, meaning that this diet is also an effective way to aid in weight loss.
Intermittent fasting and keto offer many similar benefits, including improvements in insulin sensitivity, cardiovascular health, and triglyceride levels, according to studies posted in the Journal of Translational Medicine and the Journal of Medical Internet Research.
However, the keto diet needs to be adhered to at all times in order to obtain ideal results from ketosis. In contrast, scientific research has proven that fasting methods like the 5-2 method produce the most significant weight loss in trials without requiring full-time calorie restriction.
Now that we know what the differences are, we must answer the most important question… or at least the one every coffee lover wants to know.
Can You Drink Coffee Whilst Fasting?
So, can you drink coffee whilst fasting? What about tea? The short answer is yes to both.
But there is a bit more to it.
According to nutritionist Rachel Lett at Span Health, coffee consumption is perfectly acceptable during fasting periods. She notes that coffee is an appetite suppressant and can replace breakfast or lunch during fasting days.
Research has also shown that coffee can boost ketone production and regulate blood glucose levels for enhanced metabolic health.
Lett does warn that drinking coffee on an empty stomach can pose problems to people who are caffeine sensitive. If you experience gastrointestinal stress, insomnia, or acid reflux when drinking coffee on an empty stomach, you may wish to avoid coffee and opt for water or herbal tea instead.
Tea is also an acceptable drink during fasts, including black tea and herbal teas.
If you drink coffee or tea while fasting, it’s important to drink it black, without any added milk or creamer. Certain sweeteners are permitted, as long as they do not affect your blood glucose levels. This means that sugar, honey, agave syrup, maple syrup, and other calorie-containing sweeteners are best avoided during fasts.
What to Eat and Drink While Fasting
During periods of fasting in methods like the 16-8 method, it’s essential that you don’t eat any calories at all. This will help you to maintain the state of ketosis and ensure that you obtain all the benefits it has to offer.
You are free to drink water and black tea and coffee during fasts, provided they don’t contain any creamers or sweeteners. These added extras will push your body out of ketosis and raise your blood glucose levels.
After fasting, or when performing intermittent fasting methods like the 5-2 method, it’s important to focus on eating minimally processed, healthy, unrefined foods that don’t spike your blood glucose or insulin levels excessively. This means that refined, processed foods such as biscuits, cakes, breakfast cereals, breads, pastries, sodas, crisps, and similar foods should be avoided at all times!
Food
The foods you focus on while intermittent fasting should include low-carbohydrate vegetables, including cruciferous vegetables like broccoli, cabbage, cauliflower, and Brussels sprouts. These are all full of fiber, vitamins, minerals, and antioxidants.
Avocado is another valuable addition that offers heart-healthy monounsaturated fatty acids, and legumes are also permitted. Eggs, nuts, seafood, and lean meats are also great for providing protein to balance your blood glucose levels and promote satiety and ketogenesis.
Supplements
One of the best supplements for anyone doing intermittent fasting is spermidine, a compound that’s been linked to lower mortality rates and improved longevity in humans in clinical trials.
If you suffer from obesity and insulin resistance, berberine is another valuable supplement to consider. A study published in Frontiers in Pharmacology found that berberine alleviates and reverses insulin resistance and reduces systemic inflammation by inhibiting the LTB4-BLT1 axis.
Keto Sweeteners
If you wish to promote a state of ketosis in the long term, you will need to avoid all carbohydrate-containing sweeteners that could force your body out of its ketogenic state and back into its usual habit of burning glucose for fuel. However, this doesn’t mean that you need to give up sweeteners entirely. There are many keto-friendly sweeteners that are safe to use during intermittent fasting.
According to Healthline, some of the best options to use include stevia extract, sucralose, xylitol, erythritol, and monk fruit. Stevia, sucralose, and monk fruit are significantly sweeter than table sugar and require only tiny amounts to sweeten tea, coffee and desserts without spiking your blood glucose levels. Xylitol and erythritol are roughly equivalent to table sugar in sweetness. Plus, xylitol has the added benefit of improving your dental health.
Fasting Doesn’t Mean Starving
There are many foods and drinks that you can safely consume during intermittent fasting to ensure you achieve the results you’re aiming for.
Add some high-quality supplements to your daily menu to optimize your intermittent fasting schedule and enjoy as many benefits as possible from this tried and tested dieting method.
