One of the questions that most often I happen to answer is this: up to how many kilos can you lose in a week without then running the risk of regaining them and lowering your metabolism?

It would be necessary to lose about half a kilo a week, and therefore no more than two a month, to allow our body to have a healthy weight loss and therefore avoid regaining the lost weight.

This answer is reached simply by counting a calorie restriction of 500 calories per day from our total calorie requirement, which should lead us to, if we are women and slightly active, a diet of no less than 1500 calories per week, and if we are men, a diet of about 1800/2000 calories.

Eating less would lead, in order, to nutritional deficiencies and loss of lean mass.
Both of these things combine to lower our metabolism. All good, right?

Not really: first of all because it’s just an assumption that by reducing 500 calories a day, our body can lose a kilo in two weeks.

Even today everyone knows that a kilo of body weight corresponds to about 7200 calories, few know that there is no study that has established with certainty that, if I cut 7200 calories, I automatically lose a kilo .
Weight loss is subjective, and depends on how our metabolism reacts to calorie reduction.

There are people who by cutting 500 calories a day already after a week lose a kilo.
People who cut 500 calories a day do not lose a pound even after two weeks.
The problem with calories is that the body, being a complex mechanism regulated by the metabolism, does not respond according to mathematical calculations and in particular according to a unit of measurement. In short, what one does is reason for an estimate.

As this article summarizes, this is a simplification.  
The metabolism tends to adapt.
Do you eat 500 fewer calories?
You will also move less, you will be hungrier, you will be lazier, you will tend to burn less, you will be increasingly hungry and tired.
Isn’t this your first time on a diet?
Then expect increasingly modest results.

The experts then returned to evaluate how much and how to lose weight in a week in order not to gain weight.

Are diets that, for example, promise to lose two, three pounds a week, or five in two weeks, or ten pounds in a month, are all unhealthy and unhealthy?
The Business Insider decided to ask a group of experts. Here are their answers.

1. According to Philip Stanforth, professor and director of the Fitness Institute of Texas, the ideal loss range is one pound to one and a half pounds per week.
2. According to the renowned Mayo Clinic, you shouldn’t lose more than one kilo per week, while the minimum loss should be half a kilo.
3. Other studies have shown that the slower you lose weight at first, the better your chances of maintaining your new weight.