What is the liquid diet?


  1. What is the liquid diet?
  2. What is the liquid diet for?
  3. Types of liquid diet
  4. What do you eat on a liquid diet?
  5. Why does the liquid diet make you lose weight?
  6. How many pounds can you lose on the liquid diet?
  7. Negative and critical aspects
  8. Is the liquid diet a safe system?

What is the liquid diet?

As the name suggests, the liquid diet is a diet based on the predominant intake of  liquefied foods (or real drinks).

What is the liquid diet for?

The function of the liquid diet is mainly slimming , although various specialists use it to restore metabolic parameters altered by certain metabolic diseases ( cholesterol ,  blood sugar ,  triglyceridemia ,  blood pressure, etc.).


Types of liquid diet

There are many types of liquid diet; in fact, more than to a real system, the term refers to the consistency of the foods used.

Many liquid diets are quite rigid and extreme ; not surprisingly, it is sometimes necessary to hospitalize the subjects in specialized structures (eg  Therapeutic Fasting ) .

Other types of liquid diet are more permissive and, although demanding, can be managed independently.

Liquid diets can be divided into two categories : totally liquid and partially solid.

The former, as can be easily understood, preclude the consumption of any food other than the formulas provided.

The latter, on the other hand, grant one or more meals of a solid and alternative nature; the two most common examples are:

  • Liquid diet with solid dinner;
  • Liquid diet with solid snacks.

What do you eat on a liquid diet?

Most liquid diets limit  food intake  to:  fruit juices ,  smoothies  and  smoothies  of  fruit  and / or  vegetables ; these should make up all (or almost all) meals of the day (3 to 5).

Why does the liquid diet make you lose weight?

The liquid diet makes you lose weight because it allows you to establish a negative calorie balance , that is, you eat fewer calories than the body consumes.

A characteristic of liquid diets is that, unlike “normally” solid diets, they rarely allow the establishment of a reasonably negative caloric balance, with a balanced breakdown in energy macronutrients , in the case of frequent and intense sporting activity – which is characterized by real needs very high.

It does not mean, of course, that “it is not possible” to do this; but simply that, on the practical side, it would become rather uncomfortable and meaningless.

How many pounds can you lose on the liquid diet?

Like all food systems that provide fewer calories than normal  energy needs , liquid diets also allow you to  lose weight in  proportion to the energy restriction (food choice and portions).

The problem is not so much “how much” weight you are able to break down, but rather by “what” you are reducing.

In fact, if the caloric cut becomes excessive, even if it seems paradoxical, even the liquid diet determines above all a loss of fluids, which is obviously associated with a reduction in adipose mass and another, more or less important, in muscle mass .

Effective and safe weight loss should be around 1% of weight every 7 days as the maximum limit and 0.5% as the minimum limit .

Negative and critical aspects

The negative aspects of the liquid diet are many; the most important ones are summarized as follows:

  1. Excessive calorie restriction;
  2. Lack of  nutrition education;
  3. Nutritional imbalance,
  4. Tendency to regain  weightand the “yo-yo” effect.

Statistics show that the weight loss obtained with liquid diets is not maintained over time (4th point).

Probably, the negative outcome of the system is attributable to excessive food restriction and lack of education for weight maintenance (points 1 and 2).

It is true that, in the long term, some liquid diets work better than others. In particular, mixed ones (liquids and solids) seem to have a better impact on weight retention.

Furthermore, by keeping the intake of liquid foods constant and varying only the use of  solid recipes (with weekly change), it is possible to promote understanding of their caloric impact on diet and weight (nutrition education).

For example:

  • Week 1: liquid diet and solid dinner with 200g of:  chicken breastor  cod fillet  or  cottage cheese  or  scrambled egg whites = 2 kg weight loss;
  • Week 2: liquid diet and solid dinner with 200g of:  beefsteak  or  salmon steak  or  provolone  or  whole egg omelette  = 1 kg weight loss  .

Result : the foods of week 1, with the same portions, have fewer calories than those consumed in week 2.

Is the liquid diet a safe system?

No , liquid diets are not to be considered a correct solution.

As specified, they do not provide any type of nutrition education and, on the contrary, lead to the consolidation of bad habits.

Furthermore, they are often (but it depends …) deficient in one or more nutrients ; among these, they lack essential molecules ( fatty acids  and  amino acids ), some vitamins , some mineral salts .

In theory, the drinks studied for liquid diets should guarantee a balance between the nutrients necessary for the normal conduct of human activities; nevertheless, in addition to not being specific (gender, age, etc.), these solutions ignore the variable of the level of physical activity and sometimes prevent the practice of sports .

Some liquid diets are highly hypocaloric (400-800kcal / day total) and, in the absence of medical surveillance, can compromise the state of health, causing  anemia ,  hypotension ,  hypoglycemia ,  hypokalaemia ,  dehydration  (despite being liquid),  constipation ,  metabolic acidosis ,  hypovitaminosis , depletion (or hypotonia) of  muscle mass , etc.

The  most frequent symptoms  related to the practice of a liquid diet are:  fatigue ,  dizziness ,  hair loss ,  gallstones and difficulty in evacuation.

The liquid diet is strictly not recommended in case of severe or chronic illness, pregnancy  or  breastfeeding ,  growth and type 1 diabetes mellitus .

Before embarking on a liquid diet it is necessary:

  • Be followed by a dietician or nutritionist or  dietician; however, a professional may not be willing to accept such a protocol. If so, it will check whether a  dietary supplement is needed
  • If you are part of a commercial line, inquire about the quality of the products (ingredients,  allergens,  etc.)
  • Make sure that the system:
    • It is not entirely based on liquid foods
    • Ensure gradual weight loss
    • You don’t just provide  proteinand  fiber  but provide all the necessary nutrients.

NB . The only liquid diets justifiable from a medical point of view are those preparatory to surgical interventions or intestinal endoscopic investigations. See for example the  Colonoscopy Preparation Diet .


by Abdullah Sam
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