Updated: October 2026
In short: Alkaline fasting means eating only alkaline-rich foods such as vegetables, fruit, potatoes and herbs for a few days, and avoiding meat, dairy, grains and sugar. It doesn't count as fasting in the strict sense, because you eat. The idea of the body being "over-acidified" is not scientifically proven, but the plant-based food itself is still not a bad thing.
Alkaline fasting sounds strict, but at its core it's a week of vegetables, fruit and potatoes in filling amounts. We show you what's part of it, what isn't, and why you should read the explanation behind it with caution.
What is alkaline fasting?
Alkaline fasting is a short-term way of eating, usually for 7 days, in which you eat only so-called alkaline foods: vegetables, salad, herbs, fruit, potatoes and nuts in small amounts. Meat, fish, eggs, dairy, grains, sugar, coffee and alcohol are avoided.
Unlike therapeutic fasting, you eat until you're full, so calorie intake is much higher than with a fasting method based on broth and tea. You'll find more on the methods in our overview of types of fasting.
Which foods are allowed during alkaline fasting?
| Category | Allowed | Avoid |
|---|---|---|
| Vegetables | all kinds, raw or steamed, potatoes | canned vegetables with sugar |
| Fruit | fresh fruit, unsweetened dried fruit in moderation | fruit juice with added sugar |
| Herbs and spices | fresh herbs, ginger, turmeric | very salty seasoning mixes |
| Drinks | water, herbal and fruit tea | coffee, alcohol, soft drinks |
| Protein | nuts and almonds in small amounts | meat, fish, eggs, dairy, legumes |
| Grains | usually none | bread, pasta, muesli |
The lists differ depending on the source. What matters is that you get full and drink enough.
What does a 7-day plan look like?
Here's a simple pattern you can vary:
| Meal | Example |
|---|---|
| Breakfast | fresh fruit with a handful of almonds, herbal tea |
| Lunch | roasted vegetables with potatoes and herb dip |
| Afternoon | crudités with dip or an apple |
| Evening | vegetable soup with lots of vegetables, salad |
Vegetable soups are convenient, especially in the cold. In a cleanse, you can also use our frank. soups as a warming change. But check whether they fit your alkaline fasting rules, as depending on the recipe they contain ingredients like legumes.
What does the evidence say about alkaline fasting?
There are hardly any meaningful studies on alkaline fasting itself. The consumer advice centre (Verbraucherzentrale) considers the over-acidification theory unproven. It makes sense to honestly see the positives: a week with lots of vegetables, fruit and potatoes provides fibre and vitamins and goes without alcohol and highly processed foods.
Whether this helps in the long term depends on what you eat afterwards. One week of alkaline fasting is no substitute for a permanently balanced diet following the recommendations of the German Nutrition Society.
How do you get started with alkaline fasting?
With two to three days of lead-in during which you cut back on meat, sugar and alcohol. Plan meals ahead, cook larger batches of soup or roasted vegetables and keep crudités ready. Without a plan, you reach for old habits more quickly.
- Day -2 and -1: cut back on meat, sugar, alcohol, coffee
- Shopping: vegetables, fruit, potatoes, herbs, nuts, tea
- Batch cooking: vegetable soup, roasted vegetables, dips
- Drinking: at least 2 litres of water and tea
How do you end alkaline fasting?
Reintroduce animal products and grains slowly, ideally one after the other. Start with wholemeal bread or oats, then dairy or eggs, then fish or meat. That way you notice what agrees with you.
If you like the plant-based food, keep some of it. More vegetables each day is the most lasting effect of this week.
How does alkaline fasting differ from juice fasting?
With alkaline fasting, you eat solid plant-based food; with juice fasting, juices replace meals. Alkaline fasting is a change of diet for a week, juice fasting is real fasting with much reduced solid food.
| Feature | Alkaline fasting | Juice fasting (frank.) |
|---|---|---|
| Solid food | yes, plant-based only | no |
| Typical duration | 7 days | 1, 3, 5 or 7 days |
| Cooking effort | high | none |
| Energy | much higher | 650 to 845 kcal per day |
If you have little time to cook, you'll often get on better with the Juice Cleanse; if you enjoy eating and cooking, with alkaline fasting.
Is there such a thing as over-acidification of the body?
No, at least not through food. Blood pH is tightly held between about 7.35 and 7.45, and healthy kidneys and lungs reliably buffer acids. The Verbraucherzentrale writes that normal food cannot over-acidify tissue in healthy people, and that "latent acidosis" as a widespread health problem is not proven.
True over-acidification occurs with serious conditions such as kidney disease or out-of-control diabetes, which need medical treatment. So at best, alkaline fasting can help you eat more vegetables and fruit, not "de-acidify".
Who is alkaline fasting suitable for?
For healthy adults who want to eat consciously plant-based for a week. It's less suitable with eating disorders, being underweight, during pregnancy and breastfeeding, and with kidney disease, where potassium intake from lots of vegetables and fruit plays a role. In such cases, talk to a doctor first.
After a week, you shouldn't switch abruptly to very fatty food. A gentle transition is easier to tolerate, similar to breaking a fast.
Matching picks from frank.
If you'd rather fast fully than eat alkaline, you'll find Juice Cleanses and Soup Cleanses from us for 3 to 7 days, with a guide.
You might also like
- Types of Fasting: Which One Is Right for Me?
- Lifehack: Alkaline Eating in Everyday Life
- What Is the Optimal Fasting Duration?
Frequently asked questions about alkaline fasting
How much weight do you lose with alkaline fasting?
That depends on your portion size. Because vegetables and fruit contain lots of water and little energy, many people lose a little in a week, part of which is water.
Can I drink coffee during alkaline fasting?
Not in most plans. Drink water and herbal tea, and cut back on coffee a few days beforehand.
How long can you do alkaline fasting?
Seven days is usual. Longer is possible, but the diet is one-sided, so talk to a doctor if you go beyond two weeks.
Is alkaline fasting healthy?
Lots of vegetables and fruit are good. The reasoning of de-acidification is not proven, though, and cutting out protein sources only makes sense in the short term.
Can I exercise during alkaline fasting?
Light to moderate exercise such as walking, cycling or yoga is quite possible because you eat solid food. With intense training, make sure you get enough energy and protein from nuts and potatoes, and listen to your body if you feel weak.
Note: This article is for general information and is not a substitute for medical or therapeutic advice. If you have complaints, pre-existing conditions, are pregnant or take medication, please talk to your doctor first.
