How to Get Started with Meal Replacements: A Practical Guide to Your First 7 Days

To get started with meal replacements, you only need to decide three things: which meals you are going to replace, in what format, and what you will do on the day the plan goes wrong. The usual approach is to start by replacing one or two of the main meals, leave the rest of your diet as it is, and not change anything else for the first week. This guide gives you those decisions already made, day by day, and explains what European regulations require a product to be called a meal replacement.

A heads-up, because it is the most common mistake: the first week is not an exam. It is the week you discover what time you are truly hungry, what flavors you repeat, and which meal the logistics fail on. All the information you gather from those seven days will serve you for the ones that follow.

What exactly is a meal replacement?

A meal replacement for weight control is not a protein shake or a dietary supplement. It is a food formulated to take the place of a full meal, and in the European Union it has composition conditions set by law: the Regulation (EU) 2016/1413, which amends Regulation (EU) 432/2012.

This is what the regulation requires per replaced meal:

Indicative values. They may vary depending on the product, preparation, and drained weight; consult the label or an official food composition database.

The practical consequence is what matters: when you replace a meal with a product from this category, you are not skipping a meal, you are changing it for another with the composition written on the label. And that is all the difference between skipping dinner and replacing it.

If you want the details of how the shake format compares to the rest, we develop it in meal replacement shakes for weight loss, and in are meal replacement shakes suitable for everyone we explain in what situations this category is not the right tool.

How many meals should you replace when you start?

It depends on which meal is hard for you to organize, not on how many you want to get rid of. The useful question is not "how many can I replace?" but "at what time of day do I make the worst decisions?".

These are the three usual starting points:

• One meal a day. The most convenient to try the category. It usually goes with the meal where you don't have time or a kitchen available: normally at noon in the office or dinner after a long day.
• Two meals a day. The most frequent starting point in structured low-calorie diets. It leaves one traditional meal a day, which is the one that sustains social life and habit.
• Two meals plus snacks. It is the structure of the Fitóniq 2+2+1 system: 2 Fitóniq meals, 2 Fitóniq snacks, and 1 balanced traditional meal. We explain it step by step in the practical guide to starting with Fitóniq, and you have the whole week sorted out in the 2+2+1 weekly menu, with shopping list included.

Whatever you choose, the underlying logic is the same as we explained in the calorie deficit guide: replacing meals is a way to provide structure and remove decisions, not a separate trick.

What do you need to have ready before day 1?

Less than you think, and it is best to buy it all at once so you don't improvise in the middle of the week:

1. The products for seven days, counting the meals you are really going to replace. If you are going to replace two a day, that is fourteen servings.
2. A shaker if you are going to drink shakes, and know if your product is prepared with milk, with plant-based drink, or with water. It is not a minor detail: it changes the final composition of the glass.
3. The traditional meal of the day already planned. This is the part that people do not plan and the one that breaks the week the most. Our shopping list for weight loss serves you to put it together without calculating anything weird.
4. A written plan B. Literally a sentence: "if Tuesday's meal falls through, I do X". Having it decided beforehand is worth more than Tuesday's willpower.
5. A way to record, even if it is a note on your phone. The review by Burke and colleagues (2011) analyzed 22 studies on self-reporting in weight loss programs and found that consistency in recording was the factor that repeated the most among those who followed the program, above the concrete method of recording (Journal of the American Dietetic Association).

How are your first 7 days, day by day?

This plan describes what you do, not what will happen. No one can anticipate the latter for you, and anyone who tries is selling you something.

Water and fiber references: EFSA NDA Panel, Dietary Reference Values (2010). Population reference values, not individual goals.

Notice that the column on the right does not say at any point what you will have achieved. It says what information you will have collected. The seven days serve to adjust the plan, not to judge it.

What is adjusted during the first few days?

When you change the structure of your meals, there are three things that usually need an adjustment. None is a problem, all are logistics:

• The schedules. If your replacement meal is prepared in two minutes, you will tend to eat it in less time than a traditional dish. Sitting down and giving it the same time you would give a dish changes the experience quite a bit.
• The water. Part of the water you drank came inside the meal. By changing the volume of the dish, that part has to be replaced by drinking. The EFSA references are 2.0 L/day in women and 2.5 L/day in men, counting the water from drinks and foods (EFSA Journal 2010;8(3):1459).
• The fiber. The total amount of fiber of the day depends on which products you choose and how you put together your traditional meal. The EFSA sets 25 g/day as the adequate intake for normal intestinal function in adults. How to get close to that figure without changing everything at once we explain in fiber and weight loss.

And a fourth, more psychological than physiological: the scale of the first week is not a verdict. Body weight fluctuates daily due to water, glycogen, salt, and intestinal transit, and therefore a single reading says little. We develop it in what really happens in your body in seven days.

What formats to choose for each meal?

Choosing by preparation, and not by flavor, is what makes a week work. These are the label figures of four Fitóniq products, so you can see how they are distributed:

Indicative values per prepared serving according to the label. They may vary depending on the product, preparation, and drained weight; consult the label of each product.

Proteins contribute to preserving muscle mass. This statement can only be used regarding foods that are, at minimum, a source of protein.

The practical rule: shake where you don't have a kitchen, hot dish where you do and want to sit down to eat, cream or soup where the cold or heat asks you for something else. Fitóniq offers already portioned servings and preparations ready in a few minutes, with several flavors between savory dishes, shakes, and sweets. The energy, protein, fiber, and micronutrients appear on the label of each product, so you can know its composition before incorporating it into your diet.

What do the studies say about starting like this?

Two things, and it is best to separate them.

About the category: clinical trials have studied the use of meal replacements within low-calorie diets. The meta-analysis by Astbury and colleagues (2019, Obesity Reviews) gathered 23 studies and 7,884 participants, and it is the most cited reference in the area. The results of those studies do not allow anticipating the individual result of a person. You have the complete list of the evidence we handle in our clinical studies page.

About the first week: here the relevant research is not nutrition, it is habits. In the work by Lally and colleagues (2010), 96 volunteers repeated daily a behavior of eating, drinking, or activity for 12 weeks. The time necessary to reach 95% of automaticity ranged between 18 and 254 days, with a median of 66 (European Journal of Social Psychology). One piece of data from the same study is even more useful the day you fail: skipping an isolated opportunity did not appreciably alter the process.

Translated: seven days are not enough for something to become automatic, and nothing happens. The first week is not for consolidating a habit, it is for checking that the structure fits in your life before committing to it.

Frequently asked questions

Can I replace the three meals of the day?

The diets that replace the entirety of the meals are a different category, with their own regulation, and are proposed under the supervision of a healthcare professional. To start on your own, it is reasonable to maintain at least one traditional meal a day.

Are the replacements taken with water or with milk?

It depends on the product, and it comes indicated on the label. It is not indifferent: the preparation changes the final composition of the serving, so the figures of two products are only comparable if they are prepared the same way.

What do I do if one day I skip the plan?

You continue with the next planned meal, without compensating or cutting later. In the study by Lally (2010), failing once did not appreciably alter the habit formation process. What does alter it is abandoning the entire structure.

Do I need to exercise during the first week?

It is not a requirement to start, and adding two big changes at the same time makes it harder to know which one is working. If you already train, continue. If not, it is a change for later.

How much does it cost to try a week?

Each Fitóniq product costs €23.99 the box of 7 sachets, that is 7 meals, which comes out to €3.43 per serving. If you are going to replace two meals a day for a week you need 14 servings.

In summary

• Starting with meal replacements boils down to three decisions: which meals you replace, in what format, and what is your plan B. Everything else can wait for the second week.
• A meal replacement for weight control has composition conditions set by the Regulation (EU) 2016/1413: between 200 and 250 kcal per meal, between 25% and 50% of the energy in the form of protein, and at least 30% of the NRV of vitamins and minerals.
• The first week serves to gather information (what time you are hungry, what format you repeat, which meal is complicated for you), not to evaluate yourself.
• Failing one day breaks nothing: in the study by Lally (2010), skipping an isolated opportunity did not appreciably alter the process.

If you take away anything from these seven days, let it be this: you're not testing yourself, you're gathering information about how you really eat. The structure that emerges from that is the one you'll be able to sustain next month.