Fasting-Mimicking Diets, Water Fasting, and Cleanses – Why the Effect Rarely Lasts

This post is based on my work with food and clients over the past twelve years. It is written from what I see in practice among people who seek help because they are not feeling better.

A large proportion of them have completed water fasts, fasting-mimicking diet programs, Ayurvedic or so-called sattvic cleanses, as well as various forms of juice and broth fasts. Many are well-informed, health-conscious, disciplined, and have followed advice from therapists, courses, and established health profiles. They have often experienced improvements in the beginning, sometimes very clear ones.

What brings them to me is that the symptoms have returned. Energy is low. The body feels unstable. In some cases, health has deteriorated compared to the starting point. In this text, I want to clarify why this happens and what people are actually experiencing.

Why improvement is often experienced in the beginning

Many people who try water fasting, juice cleanses, or fasting-mimicking diets experience real improvements the first time, sometimes also during one or two subsequent attempts. This is an experience that should not be dismissed. The change feels real and is often clearly noticeable in the body.

This also applies to people who do an Ayurvedic or sattvic cleanse, where the diet is simplified to, for example, rice, legumes, cooked vegetables, and spices, and where animal foods are excluded entirely. Despite major differences in language and explanatory models, the bodily reactions are often very similar.

There are several interacting reasons for this.

1. Reduction of foods that often create symptoms

When someone enters a cleanse or a fast, several factors that often contribute to imbalance in the gastrointestinal system disappear at the same time:

• sugar

• ultra-processed foods

• alcohol

• frequent snacking

For many people, this quickly leads to reduced bloating, less gas, and more stable blood sugar. Cravings and hunger may temporarily decrease. It is often experienced as the body starting to function better, but in practice it is about several burdens being removed at once.

This applies regardless of whether the method is called water fasting, a fasting-mimicking diet, or an Ayurvedic cleanse. The common denominator is not a specific physiological mechanism, but that things which often cause symptoms are removed from the diet all at once.

2. Changes in the gut environment

During fasting and very low energy intake, the availability of nutrients for gut bacteria also changes. For some, this means a temporary reduction in bacterial overgrowth or in bacteria that thrive on sugar and rapidly absorbed carbohydrates. Gas production and abdominal pressure may then decrease relatively quickly.

Fasting-mimicking diets and Ayurvedic cleanses with large amounts of vegetables, rice, and legumes can also lead to a clear change in the gut environment. The increased intake of fiber and the monotony of the diet can temporarily affect the bacterial composition in a way that is experienced as positive, especially in people who previously had an irregular or one-sided diet.

Many of these effects are not tied to fasting itself, but to the simplification of the diet and to certain foods being added or removed. Similar improvements can often be achieved by adding the same components to a regular meal. A plate with fish, brown rice, and a generous amount of vegetables can provide comparable relief for the gut, without simultaneously restricting energy and protein intake to a significant degree.

3. The effect of a markedly reduced energy intake

Most forms of fasting and cleanses involve a clearly reduced energy intake. During water fasting, no energy is consumed at all. During fasting-mimicking diets and Ayurvedic cleanses, energy intake is often far below the body’s needs.

This often leads to:

• rapid weight loss

• reduced fluid retention

• a noticeable feeling of lightness in the body

This reaction is easily interpreted as the body being “cleansed” or “reset,” when in reality it is responding to a temporary low energy intake and improved fluid balance. For many people, this is the most noticeable change, especially in the beginning.

4. Temporary changes in appetite and focus

During short periods without food, or with very limited intake, some people may experience:

• reduced appetite

• increased concentration

• a reduced perceived burden on digestion

This applies both to pure water fasting and to various forms of fasting-mimicking or Ayurvedic protocols. For some, this feels like mental clarity or improved focus. However, this is a short-term adaptation. It says nothing about how the body functions when normal eating is reintroduced, or whether the state can be maintained without energy and nutrient intake becoming insufficient.

“But what about autophagy?”

Autophagy is often highlighted as a central argument for fasting, water fasting, and fasting-mimicking diets. It is described as a process in which the body “cleans out” damaged cellular components and thereby rejuvenates or heals itself.

What is rarely mentioned is that autophagy is not a state that is switched on and off. It is an ongoing, fundamental process in the body, active in all cells all the time. It increases in certain situations, including energy deficiency, but it is not exclusive to fasting.

Autophagy also occurs:

• during normal metabolism

• between meals

• during physical activity

• with adequate nutrition combined with metabolic balance

Fasting can temporarily increase the degree of autophagy, but there is currently no established evidence showing that more autophagy automatically means better health, especially when it occurs at the expense of energy and nutrient intake. In practice, I see that the focus on autophagy is often used to justify methods that repeatedly place the body in a state of deficiency. It then becomes a theoretical mechanism used to legitimize a condition the body is not meant to be in on a regular basis.

My advice for normal autophagy: eat “normally”; that is, focus on breakfast, lunch, and dinner, avoid snacks unless required due to high physical performance, and use a 12-hour eating window. That is sufficient.

When symptoms return

The problems do not usually arise during the fast or the cleanse. They tend to appear afterward, especially when fasting and cleanses are repeated.

When people return to regular eating, often without sufficient knowledge that the body needs extra nutrient-dense and stable food after periods of restriction, many of the symptoms that previously disappeared return:

• fatigue

• cravings

• weight gain

• digestive discomfort

This does not happen because the body suddenly becomes “toxic again,” but because:

• no stable nutritional foundation has been built

• nutrient intake during the fast was insufficient and not replenished afterward

• there is a lack of understanding of what truly constitutes nutrient-dense food

The major problem: when cleansing becomes a recurring tool

When the body again feels heavy, energy is low, or there is a sense of imbalance, a quick conclusion often follows:
it is time to “cleanse” or fast again.

Cleanse, detox, and fasting then shift from being a temporary measure to becoming a way of restoring oneself regardless of actual need. Low energy, swelling, and poor metabolism are often signals that one is eating too little real food—too little protein, fiber, and fat of good quality. Fasting in that situation has the opposite effect of what is intended.

The pattern often looks like this:

• a period of everyday eating without sufficient knowledge of what constitutes good balance

• increasing symptoms or dissatisfaction

• a cleanse with rapid improvement

• a return to eating with deterioration

• a new cleanse

With each round of “cleansing” or fasting, the body is depleted of nutrients and reserves, and overall health declines slightly. The periods between fasts or cleanses become shorter. A vicious cycle begins.

This applies regardless of whether the method is water fasting, a fasting-mimicking diet, or an Ayurvedic/sattvic cleanse.

This creates a cyclical relationship with food in which:

• the body never receives continuity and sufficient building blocks

• nutrients are supplied unevenly and often inadequately

• energy intake fluctuates dramatically

Long-term consequences

After repeated periods of fasting and cleanses, I often see the same pattern in clients:

• the body becomes more energy-conserving

• weight may increase despite perceived “healthy” eating

• energy levels decline

• the initial euphoric experience of fasting or cleansing no longer appears with repetition

• hunger is perceived as something to suppress

• appetite is ignored until it becomes difficult to manage

• trust in the body’s signals diminishes

• a feeling that “something must be wrong with me—I eat so well”

The difference compared to an anti-inflammatory elimination diet

An anti-inflammatory elimination diet is based on a different approach:

• it removes what actually causes problems

• it maintains sufficient energy, nutrients, and protein

• it provides structure and continuity

• it builds tolerance over time

Instead of oscillating between absence and compensation, stability is created directly.

That is why I do not work with fasting or cleanses as a primary strategy. Not because they lack effect, but because the effect rarely lasts.

I do, however, work with elimination diets and “resets.” Click the links to read more.

When fasting replaces knowledge

Here I take a clear position. In today’s health communication, fasting, cleanses, and fasting-mimicking diets have in many contexts become a way to simplify complex issues. They offer a clear framework and a sense of control, without requiring an understanding of the body’s actual needs in detail—in other words, a quick fix. See it for what it is.

Working with an anti-inflammatory elimination diet requires something else:

• knowledge of foods and composition

• understanding of energy intake over time

• consideration of individual conditions

• patience

• removing what actually drives inflammation

• maintaining complete nutrition

• keeping an overview of energy intake (not eating too little and not eating too much)

What actually builds health over time

After many years of working as a nutrition advisor, meeting people in their everyday lives, conducting in-depth interviews, and going through health assessments, the conclusion is clear. What works long term is rarely what is most visible in the feed.

It looks like this:

• regular meals

• complete dishes with sufficient protein, fat, and vegetables

• energy intake that matches the body’s needs

• elimination of what actually creates problems (this can be individual, but some factors are shared)

• stability that allows the body to avoid swinging between deficit and compensation

For those who want to take this further, built on the same principles described in this text—stability, nourishment, and continuity.

The Holistic Reset: fully guided online program where an anti-inflammatory diet is combined with daily yoga. The focus is not on removing or purging, but on building the body up and creating clarity around how food, movement, and recovery work together.