To lose 1 kg of fat, you need to create a caloric deficit of around 7700 kcal. This restriction cannot be achieved in a single week without risking further weight gain or metabolic imbalance.
On the other hand, a 4-week structured weight loss program enables you to effectively lose 1kg of body fat while preserving your muscle mass and maintaining your sporting performance.
Muscle drying goes beyond simple weight loss, aiming to eliminate fat mass alone. Let's take a look at how to determine an effective program for losing 1 kg of fat in a sustainable way (and not in a week).
Weight loss program calculator
Plan your healthy weight loss based on scientific principles
Your personalized program
Recommended schedule
Nutritional recommendations
- Protein: 1.8 to 2g/kg body weight To preserve muscle mass during the deficit
- Carbohydrates: 50-55% of calorie intake Concentrate them around your workouts
- Lipids: 25-30% of calorie intake Essential for hormonal functions
Training recommendations
- Strengthening your muscles 2-3 sessions per week to maintain your muscle mass
- Moderate cardio 2-3 sessions of 30-45 minutes to increase caloric expenditure
- Daily walking Aim for 8,000 to 10,000 steps a day
Scientific basis
- 1kg fat = 7700 kcal Recommended deficit: 200-500 kcal/day
- Safe weight loss 0.5 to 1% of body weight per week
- Recommended cycles Prevents metabolic adaptation and the yo-yo effect
Please note: this program is only an estimate, a proposal in relation to your objectives. Every body reacts differently to caloric deficit. Adjust according to your results and feelings. For further details, consult a specialized health professional.
How does our body eliminate fat?
Fat doesn't magically disappear after intensive exercise. Weight loss is based on the principle of energy balance. When caloric expenditure (via physical activity and basal metabolic rate) exceeds energy intake (via food), the body draws on its reserves (fat, but not only fat) to make up the shortfall.
During periods of caloric restriction, the body not only loses fat, it also draws on muscle to produce energy.
A well-managed weight loss program avoids this loss of muscle while reducing fat, thanks to a moderate calorie deficit, a suitable diet and optimized training.
How many calories does 1 kg of fat represent?
Body fat is considered to contain 72% to 87% pure lipids. In fact, body fat is made up of lipids, but also some proteins and fluids. As a result, even though 1 g of fat theoretically provides 9 kcal, one kilogram of body fat is equivalent to around 7700 kcal.
However, a calorie deficit of 7700 kcal in one week is far from a good idea. Not only could losing that many calories in 7 days have adverse effects on your health, but it could also be followed by even greater weight regain. This is often referred to as the yo-yo effect, when rapid weight loss leads to fat regain.
To preserve lean body mass, the recommended deficit is between 200 and 500 kcal per day. The aim is to achieve a weight loss of 0.5 to 1% of body weight per week, and a loss of around 2 kg per month.
To lose weight effectively, you first need to know your daily energy requirements by calculating the number of calories linked to your basic metabolism and your level of physical activity. Our caloric deficit calculator enables you to determine your exact caloric requirements for weight loss.
Caloric and macronutrient requirements calculator
Recommended macronutrient breakdown (approx.)
The phase of gradual reintroduction of calories after the deficit period is very important. It helps avoid the yo-yo effect, where the body's metabolism slows down (= lower daily energy expenditure) and fat storage increases.
Everyone reacts differently to caloric deficit. Two people of the same height, weight and age can achieve very different results with the same calorie intake. It is advisable to adjust the deficit regularly according to the results observed and how you feel. It goes without saying that the athlete must maintain a healthy, varied and balanced diet, both during and especially after the dry period.
How to lose 1 kilo of fat?
Here is an example of a progressive weight loss program to lose 1 kilo in 4 weeks:
Note that this example represents the ideal case where 100% of the deficit is drawn from fat.
| Week | Phase | Daily deficit | Weekly deficit | Weekly weight loss |
|---|---|---|---|---|
| 1 | Initial phase | 250 kcal/day | 1750 kcal | ~ 0.2 kg |
| 2 | Maintenance phase | 300 kcal/day | 2100 kcal | ~ 0.3 kg |
| 3 | Maintenance phase | 300 kcal/day | 2100 kcal | ~ 0.3 kg |
| 4 | Final phase | 250 kcal/day | 1750 kcal | ~ 0.2 kg |
| Total | - | - | 7700 kcal | Loss of 1 kg |
It's not just a question of counting every calorie, but also of paying attention to your nutrition. Food choice plays an important role in maintaining sporting performance and preserving muscle mass during a deficit phase.
Whole proteins, complex carbohydrates and essential fats must be consumed in precise ratios and in sufficient quantities to support effort, optimize recovery and achieve better metabolic health. An athlete who simply reduces portions without paying attention to the quality of his or her diet risks compromising performance and body composition.
The importance of diet in times of caloric restriction
A poorly constructed caloric deficit can lead to a significant loss of muscle mass and a drop in energy. Here's the ideal macronutrient breakdown for muscle lean:
- Protein (4 kcal/g): 1.8 to 2 g/kg body weight (20-25% of calorie intake)
- Carbohydrates (4 kcal/g): approx. 3 g/kg
- Fat (9 kcal/g): approx. 1.3/1.4 g/kg
Proteins provide the amino acids needed for muscle preservation and repair. A post-training protein + carbohydrate shaker enables athletes to limit catabolism while effectively controlling their calorie intake.
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Carbohydrates (wholemeal bread, oat flakes...), although to be reduced in a dry diet, are essential for maintaining training intensity. They are an essential source of energy for high-intensity exercise such as muscle-building or intense running sessions. Ideally, they should be consumed during (after) training sessions.
The quality of carbohydrate sources is also important - wholegrain fruits and cereals provide essential micronutrients as well as energy.
Lipids play a fundamental role in maintaining hormonal functions, which are particularly important during periods of caloric restriction. Too severe a reduction can disrupt the production of testosterone and other anabolic hormones, compromising performance and recovery.
During periods of restriction, the risk of deficiency increases, so athletes on a diet must not forget to eat fruit and vegetables every day to provide micronutrients (vitamins and minerals).
How long does it take to lose 10 kg?
Let's now look at how to apply our method to a more substantial goal: weight loss of 10 kg, i.e. a total deficit of around 77,000 kcal to be created (very) gradually.
To preserve muscle mass and sporting performance to the maximum, a deficit of 300 to 500 kcal per day is required. In addition, weight loss can reach 0.5 to 1% of body weight per week, i.e. around 0.4 to 0.8 kilos per week for an 80 kg person.
To lose 10 kg, you would need to follow a 6-month weight loss program with a maintenance phase of around -500 kcal / day. But this is not the recommended duration of a weight loss program. This is because our bodies adapt to caloric deficit: the lower the caloric intake, the lower our basal metabolic rate, leading to a drop in overall energy expenditure. Although the deficit can be gradually reduced, this approach is not recommended as it would lead to a further drop in metabolism and a decline in performance.
To lose 10 kg by muscle drying, we recommend 2 cycles of 3 months, with the aim of losing 5 kg per cycle. A break of 2 to 4 weeks is recommended between the two cycles to allow the body to return to its basal metabolism.
In the case of long-term weight loss goals, success depends less on a temporary diet than on the adoption of a new lifestyle. People who maintain their results over the long term are those who make lasting changes to their eating and exercise habits, rather than those who undertake radical calorie restrictions.
In addition to muscle strengthening, which preserves lean body mass, incorporating endurance activities such as running, swimming or cycling increases daily calorie expenditure. Walking, often underestimated, is an excellent way of burning calories without generating excessive fatigue.
3-month caloric deficit program with a 5 kg weight loss objective:
Please note that these values represent the ideal case where 100% of weight loss is linked tofat loss, which implies a sufficient protein intake. Remember also that everyone reacts differently to caloric deficit, and that it is important to adapt this deficit to one's feelings and to the actual loss observed.
| Period | Phase | Daily deficit | Weekly deficit | Weekly weight loss |
|---|---|---|---|---|
| Weeks 1 | Initial phase | 200 kcal/day | 1400 kcal | ~ 0.2 kg |
| Weeks 2 | Initial phase | 400 kcal/day | 2800 kcal | ~ 0.4 kg |
| Weeks 3-10 | Maintenance phase | 500 kcal/day | 3500 kcal per week | ~ 0.5 kg per week |
| week 11 | Final phase | 400 kcal/day | 2800 kcal | ~ 0.4 kg |
| Weeks 12 | Final phase | 200 kcal/day | 1400 kcal | ~ 0.2 kg |
| Total (24 weeks) | - | - | 36,400 kcal | ~ 5 kg |
How long does it take to lose 15 kg?
15 kg of body fat represents a total deficit of 115,500 kcal to be created gradually. For a muscle-drying approach, we recommend following 3 cycles of 3 months with the aim of losing 5 kg per cycle. A break of 2 to 4 weeks is recommended between cycles to allow your body to return to its basal metabolism, which means just under a year to achieve your weight loss goal.
People who maintain lasting weight loss are those who adopt a balanced diet over the long term.
How long does it take to lose 20 kg?
By the same token, 20 kg of fat mass represents 154,000 kcal of total deficit to be created progressively. For a muscle-drying approach, we recommend following 4 cycles of 3 months with the aim of losing 5 kg per cycle.
A break of 2 to 4 weeks between cycles is recommended to allow your body to return to its basal metabolism, which corresponds to more than a year to achieve your weight loss goals.
How long does it take to see the results of a blow-dry?
Losing weight effectively and sustainably requires a methodical approach. As we've seen, creating a moderate calorie deficit of 500 kcal per day allows you to aim for a weight loss of around 0.5 kilos per week, without compromising muscle mass or metabolic rate. So, without drastic dieting or anything else, it's possible to achieve visible, healthy and lasting results from the very first week. But beware: whatever your objectives, this deficit must be achieved gradually, both in the calorie reduction phase and in the reintroduction phase.
Conclusion
To lose weight, the energy balance must be in favour of a slight, gradual and controlled deficit. Regular physical activity, combining muscle strengthening and cardiac exercise such as running, helps burn calories while preserving lean body mass. Adequate hydration and quality sleep also promote recovery and weight loss.
To avoid the yo-yo effect and weight regain, it's important to adopt healthy, sustainable eating habits. For example, by favouring fibre-rich foods such as wholemeal bread over white rice.
Remember that every body is different: the time needed to lose 1, 10, 15 or 20 kg varies according to body mass index, waist circumference, basal metabolism and lifestyle. The aim is not just to reach an ideal weight, but to improve body composition and overall health.
Finally, let's not forget the importance of a varied, balanced diet, made up as much as possible of high-quality, unprocessed, additive-free foods.
