Intermittent fasting is a form of nutrition and dieting, where one alternates between phases of normal food intake and diets without calorie intake in short intervals.

Various forms of interval fasting are popular, and the basic principle remains the same – during fasting, you may only consume foods without calories, followed by an interval where you may eat according to your normal habits.

We have summarized in a small overview where exactly the difference lies and which drinks and foods are suitable for fasting.

How does intermittent fasting work?

The human digestive system has continuously adapted to new dietary patterns over time. The modern eating plan with three large meals daily and sugary snacks and drinks in between is relatively new – according to numerous studies, our body is set up for a different form of nutrition: interval fasting.

During fasting, the body can digest the foods consumed undisturbed and break down excess substances from the cells. Ketosis occurs – your body derives its energy no longer from carbohydrates in food, but instead relies on stored fats. The intestines are cleansed naturally, and the risk of obesity, diabetes, and a variety of age-related conditions decreases significantly.

Three forms of interval fasting are particularly popular – what exact intervals are right for you and your personal goals should be experimented with in small comparisons.

Alternate Day Fasting

With alternate day fasting or every other day fasting, a 24-hour fasting period is followed by a 24-hour phase of normal food intake. Alternate day fasting is the most widely used method of interval fasting and is also applied in most studies on this topic. In laboratory settings, the health benefits of this dieting method are already demonstrable.

Whole Day Fasting

The whole day fasting model requires a bit more self-discipline with fasting intervals over one or several full days. However, you should not have more than three full fasting days per week to ensure your body regularly receives all the nutrients it needs. The variant with two fasting days per week is the most popular, also known as 5/2 fasting.

16/8 Fasting

For beginners, the so-called 16/8 fasting is an effective method to reduce overweight and give the digestive system regular breaks. Each day is divided into two eating phases – after 16 hours of fasting, you can consume food ad libitum for 8 hours. At certain times of the day, your body usually fasts on its own – for example, during sleep or when exercising. By simply skipping breakfast, the 16/8 framework can be easily maintained.

What does fasting actually mean?

Fasting refers to the omission of specific foods for spiritual or health reasons. Intermittent fasting primarily involves refraining from calories and fiber. The body's fat reserves are reduced during fasting, and the intestines can empty naturally. No new harmful substances are absorbed through food, allowing for better breakdown of deposited substances – this has a cancer-inhibiting effect and rejuvenates the skin.

An adult should consume between 0 and 600 calories during a fasting interval, depending on their diet goals. Active people and athletes generally need more calories and should either choose short fasting intervals like 16/8 or prepare small snacks from easily digestible foods in between.

Weight loss with intermittent fasting

Body fat is reduced by a calorie deficit – so you simply need to consume less energy through food than you expend throughout the day. This means that you can basically eat and drink anything as long as you do not exceed your overall calorie needs. If you love snacking, you don't have to completely forgo it. With low-calorie foods like cucumber, melon, and asparagus, you can also prevent hunger pangs and combat stomach growling.

Intermittent fasting has been shown to lower insulin levels and stimulate the release of growth hormones. The choice of foods has little effect on weight loss – whether you prefer a low carb diet or carbohydrate-rich foods, what matters during intermittent fasting is the balance between consumed calories and expended energy.

The fasting periods and limited eating times can help you better control your calorie intake and achieve your desired weight.

Fast your way to health

Intermittent fasting is beneficial to health in many ways and is not only used for weight loss. Even people without weight issues feel significantly fitter and healthier through regular interval fasting.

If you want to eat healthily, there is a list of no-go's that you should avoid during both fasting and normal food intake:

No-Gos for Healthy Fasting

• Try to avoid unhealthy fats, meat, and sugar.

• Cigarettes are not a good idea and alcohol is taboo.

• Avoid stress!

Test your willpower

Discipline is an effective factor in boosting self-confidence. Fasting improves your self-control and body awareness. If you want to fast for religious reasons or to optimize yourself, you should only do so in consultation with a nutrition expert or a general practitioner – after all, you don’t want to deplete your body, but rather strengthen and keep it fit in the long term.

Going without food for more than two days can lead to digestive problems and bloating. Therefore, during longer fasting intervals, you should definitely drink plenty of water and pay attention to your electrolyte balance.

Enjoy the freedom of choice while losing weight

You can integrate intermittent fasting into your daily routine according to your personal needs. You have free choice when it comes to eating and drinking, as long as you stay below your normal calorie value. Whether you allow yourself 5 or 500 calories during a fasting interval, is entirely up to you and depends on your current body weight.

You should always discuss your diet plan with a professional who can guide you and provide helpful tips. If you find it particularly challenging to refrain, you can start with a higher calorie maximum and gradually increase from fasting interval to fasting interval. A zero-calorie diet during fasting is, however, only advisable for people with severe obesity.

Most importantly, you should feel comfortable while fasting and get a sense of how to do good for your body instead of suffering from the restrictions. The body quickly adapts to the new rhythm, and the fasting intervals will become easier for you over time.

Small and large successes in fasting

Don’t worry – thanks to the simple and effective system behind interval fasting, you don’t have to change your eating habits, even during your diet. The meal plan for periods of normal eating and fasting is fundamentally the same. Only the calorie values differ significantly.

This way, you can continue to enjoy your coffee with cream or have breakfast with colleagues in the cafeteria without jeopardizing your diet. You determine your daily meals, just as you decide the length of your fasting phases and the maximum calorie intake you want during fasting.

Are sweeteners and light products okay?

Artificial sweeteners and light products contain very few calories and can make your fasting period easier. However, consuming them during fasting periods is not recommended, as artificial substances are counterproductive to the autophagy process.

Regarding eating periods: There is evidence that sweeteners affect blood sugar levels. Some fasters report they stimulate appetite. Sweeteners likely do not affect insulin levels – light foods are mainly suitable for diabetics. Many beverages and foods can be transitioned from sugar to sweeteners in moderate amounts during food intake phases. But pay attention to whether they truly benefit you; observe how you feel.

Light colas usually contain as much caffeine as regular colas – caffeine additionally stimulates metabolism and can be beneficial for becoming slimmer. But watch out! Many artificial additives burden the cells and are difficult to eliminate from the body – if you fast for health reasons, it is advisable to choose foods that are naturally less sweet.

A sweet summer tip is the classic watermelon – these sweet fruits contain hardly any calories and ensure a pleasant feeling of fullness.

Do I need to watch my fats?

Fats consumed during fasting are generally excreted as fibers. It is important that you limit your intake of carbohydrates and proteins as much as possible. Your body derives energy from stored fat cells through ketosis – the so-called hunger metabolism sets in with less than 50g of carbohydrate intake per day and is independent of the fats consumed.

What can I drink while fasting?

There are a few more drinks that can make fasting easier and supply your body with the nutrients it needs. Pure water helps with detoxification, but deficiencies may occur during longer fasting intervals. With small tricks, you can turn your drinks into calorie-poor energy suppliers:

1. Water with baking soda

You should definitely pay attention to your fluid intake during fasting and drink plenty of water. With longer fasting intervals (>36 hours), you not only lose fat but also valuable minerals that the body needs to survive.

A spoonful of baking soda dissolved in a glass of water can already help – baking powder consists of 100% sodium bicarbonate (NaHCO3) and is thus identical to most electrolyte mixtures from the pharmacy.

This way, you won't lose vital salts during fasting, and your hunger will noticeably decrease. The particularly harsh taste ensures this too – water with baking soda is unfortunately only tolerable in small doses and is not suitable as a drink for the entire day.

2. Glauber's salt

Glauber's salt is a well-known home remedy for relieving constipation. At the beginning of a fasting interval, you can dissolve between 5 and 20 milligrams of Glauber's salt (Na2SO4·10H2O) in water to stimulate the body's detoxification. Higher doses pose risks of diarrhea and deficiencies, so you should be careful with the dosage.

3. Herbal tea

Many herbal tea varieties have a positive effect on the body and suppress your hunger. For instance, chamomile tea soothes the stomach during bloating and heartburn, while black tea and peppermint have a stimulating effect. Herbal tea detoxifies the body and stimulates natural autophagic processes.

Avoid tea mixtures made from dried fruits for detoxification; however, on regular fasting days, sweet tea can be used as a low-calorie energy supplier. Other recommended tea varieties include jasmine tea and green tea. Green tea contains many antioxidants and plant-based amino acids, which stimulate the release of neurotransmitters in the brain and effectively break down toxins in the body.

4. Coffee

The most widely used secret weapon against fatigue and hunger is black coffee. The caffeine contained stimulates blood circulation and metabolism; additionally, coffee also causes a diuretic effect in the cells. Therefore, you should always drink a glass of water along with your coffee. With more than 2-3 cups of coffee per day, a certain tolerance develops, so you should enjoy this hunger killer in moderation.

5. Water with apple cider vinegar

Despite its sour taste and strong odor, vinegar is a healthy addition to mineral water, lemon soda, or cucumber water. Apple cider vinegar contains many important minerals like potassium, iron, and magnesium. Your hunger diminishes, and harmful enzymes in the intestines are broken down. Despite its high acidity, vinegar can prevent heartburn in the long run and balance the body's pH levels.

6. Saltwater

During a pure water diet, you should occasionally mix a pinch of sea salt into your drinks to keep your electrolyte balance in check. Salt is particularly important for cellular metabolism and is excreted in large quantities during detoxification.

Usually, we consume enough salt through our daily food intake – if you refrain from regular meals, this deficit must be compensated with supplements. However, too much salt harms the cells again – like all foods for fasting, you should enjoy salted water only in moderation and regularly drink a glass of clear mineral or tap water.

Last tips for a low-calorie diet

With whole day fasting or fasting over several days, it can be quite uncomfortable at the beginning to take no solid food at all. If you want to lose weight solely and only detoxify your body peripherally, some foods with particularly low calorie content can provide relief and ensure a pleasant feeling of fullness without throwing off the energy balance during fasting.

Cucumber and iceberg lettuce contain hardly any calories, as do Chinese cabbage, although the latter can cause bloating and stomach pain in large quantities. The best remedy for an empty stomach feeling is a light vegetable broth – it is easily digestible, stimulates the taste buds, and contains very few calories, carbohydrates, and proteins.

Ready to start your fasting journey? In the BodyFast app, you will find your optimal fasting plan, delicious recipes tailored to your fasting lifestyle, supportive weekly tasks, daily motivational coaching, and much more.